ELECRAFT K2
160-10 Meter
SSB/CW
Transceiver
Owner’s Manual
Revision XC, Jan. 25, 1999
Copyright  1999 Elecraft
All Rights Reserved
This revision of the K2 Owner’s Manual is for use by Field
Test participants only. Missing or inaccurate information
will be corrected in the next revision.
K2 Manual 1/24/99 V.XC ©1999 Elecraft
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Table of Contents
1.
INTRODUCTION .............................................................................................................................................................................. 4
2.
SPECIFICATIONS............................................................................................................................................................................ 4
3.
PREPARATION FOR ASSEMBLY ................................................................................................................................................... 7
4.
CONTROL BOARD ........................................................................................................................................................................ 13
5.
FRONT PANEL BOARD ................................................................................................................................................................ 22
6.
RF BOARD..................................................................................................................................................................................... 34
7.
FINAL ASSEMBLY......................................................................................................................................................................... 78
8.
OPERATION .................................................................................................................................................................................. 81
9.
MODIFICATIONS ......................................................................................................................................................................... 110
10. THEORY OF OPERATION .......................................................................................................................................................... 111
11. TROUBLESHOOTING ................................................................................................................................................................. 119
12. INTERNAL OPTIONS .................................................................................................................................................................. 126
PARTS LIST ......................................................................................................................................................................... APPENDIX A
SCHEMATIC ......................................................................................................................................................................... APPENDIX B
BLOCK DIAGRAM................................................................................................................................................................ APPENDIX C
PHOTOGRAPHS .................................................................................................................................................................. APPENDIX D
K2 Manual 1/24/99 V.XC ©1999 Elecraft
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K2 Manual 1/24/99 V.XC ©1999 Elecraft
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1. Introduction
The Elecraft K2 is a high-performance, synthesized transceiver that
provides CW and SSB operation on 160-10 meters. It is a true dualpurpose transceiver, combining the operating features you’d expect in
a home-station rig with the small size and weight of a rugged, goanywhere portable. The K2 is also the first transceiver to offer these
features in kit form.
The basic K2 operates on 80-10 meter CW, with adjustable power
output of over 10 watts. You can also customize your K2 by choosing
from a wide range of internal option kits. These include:
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SSB adapter
noise blanker
160 meter adapter + receive antenna switch
20W automatic antenna tuner
internal rechargeable battery
host computer interface
For those who prefer a higher-power station, we’ll be adding an
internal 100W power amplifier kit in the near future1. Other future
options include an internal 6m transverter, high-performance audio
filter, and a variety of matching station accessories.
The K2 is an intermediate-to-advanced kit, yet you’ll be pleasantly
surprised at how uncomplicated it is to build and align. All of the RF
(radio-frequency) circuitry is contained on a single board, while two
plug-in modules provide user interface (UI) and control functions.
1
The 100W power amp option displaces the ATU and battery.
Wiring is minimal, unlike traditional kits which depend on complex
wiring harnesses.
A unique feature of the K2 is that it provides its own built-in test
equipment, including a digital voltmeter, ammeter, wattmeter, and
frequency counter. Construction of the kit is sequenced so that these
functions are ready to be used when you begin construction of the RF
board.
In addition to this owner’s manual, you’ll find extensive support for the
K2 on our website, www.elecraft.com. Among the available materials are
manual updates, application notes, photographs, and information on new
Elecraft products. There’s also an Elecraft user forum.
We’d like to thank you for choosing the K2 transceiver, and hope it meets
your expectations for operation both at home and in the field.
Wayne Burdick, N6KR
Eric Swartz, WA6HHQ
Field-Test Acknowledgements
Getting the K2 ready for its field test would not have been possible, or at
least would have taken a lot longer, without the help and encouragement
of Lerma Swartz, Lillian Svec, Bob Dyer, Shigehiro Kinoshita, Conrad
Weiss, and Rob Capon. We’re also grateful for the patience shown by
our field testers.
K2 Manual 1/24/99 V.XC ©1999 Elecraft
2. Specifications
All measurements were made with a 13.8V supply and 50 ohm load at
the antenna. Numeric values are typical; your results may be somewhat
different. Specifications are preliminary and subject to change without
notice.
General
Size
Cabinet
Overall
3.0” H x 7.9” W x 8.3” D
(7.5 x 20 x 21 cm)
3.4” H x 7.9” W x 9.9” D
(8.5 x 20 x 25 cm)
Weight
3.3 lbs (1.5 kg)
Supply Voltage
8.5 to 15VDC (13.8V nominal);
reverse-polarity protection
Current drain,
Receive 100mA in minimum-current
configuration; 150-200mA typical
Transmit2
Frequency control
2
1.8A at 10 watts
PLL synthesizer w/single VCO
covering 6.7-24 MHz in 9 bands;
fine steps via DAC-tuned VXCO
Varies with band, supply voltage, configuration, and load impedance.
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K2 Manual 1/24/99 V.XC ©1999 Elecraft
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Load Tolerance 2:1 or better SWR recommended;
will survive occasional operation
into high SWR
Frequency range, MHz
Guaranteed
3.5-4.0, 7.0-7.3,
10.0-10.2, 14.0-14.5, 18.0-18.2,
21.0-21.6, 24.8-25.0, 28.0-28.8
Typical [TBD]
160m (opt.)
1.8-2.0
T-R delay
10ms-1.5sec, adjustable
Receiver
VFO
Stability
[TBD]
3
Sensitivity (MDS)
3rd-order Intercept
2nd-order Intercept
Preamp On
-135dBm
0 to +7.54
+77
Preamp Off
-130dBm
+14
+78
125dB
96
133dB
97
4.915 MHz (single conversion)
Accuracy
+/- 30Hz typ. if calibrated
Resolution
10 Hz
Tuning steps
10 Hz, 50 Hz, and 1000 Hz
Dynamic Range,
Blocking
Two-tone
20 (10 general, 10 pre-assigned
to available bands)
I.F.
Memories
Selectivity,
CW
Transmitter
Power Output
Duty Cycle
SSB
0.5W to 10W (typ.), all bands;
power setting resolution 0.1W,
power reading accuracy 10% @ 5W
5W, 100%
10W, 50%
Spurious products
(Transmitter, continued)
-40dB or better @ 10W (-50typ)
Harmonic content
-45dB or better @ 10W (-55typ)
RIT/XIT Range:
+/- 1.2 kHz, 10 Hz steps
Audio output:
1 watt (typ) into 4 ohm load
3
See Frequency Calibration Techniques (Operation section, under Advanced
Operating Features).
4
5-pole variable-bandwidth crystal
filter, 200-1500 Hz
[TBD]
Varies with band.
K2 Manual 1/24/99 V.XC ©1999 Elecraft
Keyer
Keying modes
Iambic A and B
Speed Range
Approx. 9 - 40 WPM
Messages
3 buffers, 84 bytes each,
nonvolatile; auto-repeat
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K2 Manual 1/24/99 V.XC ©1999 Elecraft
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3. Preparation for Assembly
Overview of the Kit
The K2 is a highly modular transceiver, both physically and
electrically. This concept extends to the chassis, as can be seen from
Figure 3-1. Any chassis element can be removed to facilitate assembly
or troubleshooting. (Also see photos in Appendix D.)
As shown in Figure 3-2, there are three printed circuit boards (PCBs) in
the basic K2 kit: the Front Panel board, Control Board, and RF board.
The Front Panel and Control boards plug into the RF board directly to
eliminate point-to-point wiring. Gold-plated contacts are used on these
connectors for reliability and corrosion resistance.
Side
Panel
RF
Control
Top Cover
Heat
Sink
Front
Panel
Front
Panel
Bottom
Cover
(Right side panel
not shown)
Figure 3-2
Figure 3-1
K2 Manual 1/24/99 V.XC ©1999 Elecraft
There are six steps in the K2 assembly process:
1.
2.
3.
4.
5.
6.
Control Board assembly
Front Panel Board assembly
RF Board assembly and test, part I (control circuits)
RF Board assembly and test, part II (receiver and synthesizer)
RF Board assembly and test, part III (transmitter)
Final assembly
This assembly sequence is important because later steps build on the
previous ones. For example, in step 3 you’ll put the modules together
for the first time, allowing you to try out the K2’s built-in frequency
counter. The counter will then be used in step 4 to align and test the
receiver and synthesizer on 40 meters. In step 5 all the pieces will come
together when you complete the transmitter and filters, then align the
K2 on all bands. The last few details—speaker, tilt stand, etc.—will be
wrapped up in step 6.
Many illustrations are provided in the manual to clarify assembly steps.
In addition, you should familiarize yourself with Appendix D, which
provides photographs of the K2 and its three circuit boards in various
stages of assembly.
Note to Field Testers
During field testing of the K2, you will no doubt discover minor
problems with the kit's documentation, components, etc. Please contact
us if you find something that we've missed. We will suggest corrective
measures as quickly as possible, and we'll ship you any parts needed.
The next revision of the manual will include a number of additional
illustrations and photos. The Theory of Operation and Troubleshooting
sections will also be much more extensive, and we’ll add much more
information for beginning builders and operators (including a glossary
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of terms). Revised manual sections will be posted to our website in
downloadable form.
Unpacking
Note: Do not open any of the component bags until instructed to do so.
Small components can easily be lost or confused with similar parts if
you unpack the entire kit at once.
When you open the kit you should find the following items:
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six chassis pieces, wrapped (Figure 3-1)
three printed circuit boards (Figure 3-2)
FRONT PANEL board components bag, which includes the LCD
and its backlight assembly in individual small bags
CONTROL board components bag
RF board components bag
MISCELLANEOUS components bag
4 ohm Speaker
tube of DPDT latching relays
Enamel and hookup wire
If any of the above items is missing or damaged, contact Elecraft.
Your kit has been carefully packed, so it is unlikely that any
components are missing. However, if you prefer to do an inventory of
parts, you may do so at any major stage in the assembly process using
the complete parts list in Appendix A. The parts list includes
photographs or illustrations of each type of component. Even if you
don’t do an inventory, it is helpful to familiarize yourself with the parts
list in case you need to refer to it later.
K2 Manual 1/24/99 V.XC ©1999 Elecraft
Tools
The following specialized tools are supplied with the K2:
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.050” (1.3mm) Allen Wrench, short handle
5/64” (2mm) Allen Wrench, long handle
Double-ended plastic inductor alignment tool
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Assembly Notes
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This symbol is used to alert you to important information about
assembly, alignment, or operation of the K2. You should read and
understand this information before proceeding.
Step-by-Step Assembly
In addition to the tools listed above, you will need these standard tools:
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Fine-tip soldering iron, 15-25 watt (or a temperature-controlled
soldering station)
IC-grade, small-diameter solder (DO NOT use acid-core solder or
any type of flux)
Desoldering tools (wick, solder-sucker, etc.)
Needle-nose pliers
Small diagonal cutters
Small phillips screwdriver
Very small flat-blade screwdriver (for 2-56 bezel screws and
trimmer capacitors)
While not required, the following items are recommended:
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DMM (digital multimeter) for doing resistance and voltage checks.
Even an inexpensive DMM can provide a number of useful
capabilities, including diode and capacitance measurement.
Illuminated magnifying glass
Anti-static work surface and wrist strap (see Integrated Circuits
and ESD, below, for more details)
Each step in the K2 assembly process is accompanied by a check-box.
As you complete each step, put a mark in the box:
In some steps you will actually be installing multiple components of a
particular type. In this case the instructions will be followed by a table
listing all of the components to be installed, so you won’t need to refer
to the parts list during assembly. The order that the components are
installed corresponds closely to their locations on the PC board.
Assembly generally begins with low-profile components such as
resistors and diodes, then works up to the higher-profile parts. This
keeps the board stable as you turn it over each time to solder. Do not
skip any steps; you may find that you’ve installed one component that
hinders the installation of another.
Top and Bottom Components
A number of components in the K2 are mounted on the bottom of the
PC boards to improve component spacing or for electrical reasons.
Component outline symbols are provided on both sides of each board,
so it will always be clear which side a particular component goes on.
You’ll be able to tell the top of the board from the bottom easily: the
top side has far more parts.
K2 Manual 1/24/99 V.XC ©1999 Elecraft
Components which are mounted on the bottom of a board are identified
on the schematic with this symbol:
Identifying Capacitors
Small (< 1000 pF) fixed capacitors are usually marked with one, two,
or three digits and no decimal point. If one or two digits are used, that is
the value in pF (picofarads). If there are three digits, the third digit is
usually a multiplier. For example, a capacitor marked “151” would be
150pF (15 with a multiplier of 101). Similarly, “330” would be 33 pF,
and “102” would be 1000 pF (or .001µF).
Occasionally, capacitor manufacturers use "0" as a decimal place
holder rather than a multiplier, so that “330” might actually mean 330
pF, not 33 pF. Markings shown in the parts list should clear up any
confusion. If in doubt, you may wish to measure the capacitor using a
DMM.
Fixed capacitors with values over 1000pF may use a decimal point in
the value, such as .001 or .02. This is the value in microfarads (µF).
Capacitors also may have a suffix after the value, such as “.001J.”
You won’t need to use suffixes in identifying capacitors.
Color Code
All resistor and RF choke color bands are provided in the text along
with their values. However, it is helpful to familiarize yourself with the
color code to allow you to identify these components without having to
refer to the text or parts list.
The color-code chart, Figure 3-3, shows how to read the four color
bands on 5% resistors. 1% resistors are similar, except that they use
five bands (three significant digits, multiplier, and tolerance). For
10
example, a 1,500 ohm (1.5k) 5% resistor has color bands BROWN,
GREEN, and RED. A 1.5k, 1% resistor has color bands BROWN,
GREEN, BLACK, BROWN. The multiplier value is 1 rather than 2 in
the 1% case because of the third significant digit.
The markings on RF chokes reflect their value in microhenries (µH).
Like 5% resistors, chokes use two significant digits and a multiplier.
Example: an RF choke with color bands RED, VIOLET, BLACK
would have a value of 27µH.
K2 Manual 1/24/99 V.XC ©1999 Elecraft
Resistor Color Code
Tolerance
(gold = 5%)
Multiplier
Second Digit
First Digit
Color
Black
Brown
Red
Orange
Yellow
Green
Blue
Violet
Gray
White
Digit
Multiplier
0
1
2
3
4
5
6
7
8
9
Figure 3-1
x1
x 10
x 100
x 1K
x 10K
x 100K
x 1M
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K2 Manual 1/24/99 V.XC ©1999 Elecraft
Integrated Circuits and ESD
The K2 transceiver uses integrated circuits and transistors that can be
damaged by electrostatic discharge (ESD). Problems caused by ESD
can often be difficult to troubleshoot because components may only be
degraded rather than fail completely. To avoid such problems, we
recommend that you take the following anti-static precautions:
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Remove carpets in your workbench area, or treat them with
antistatic spray
If you use a rubber floor mat to guard against electric shock, make
sure it is of the anti-static type; any other type of rubber mat will
increase ESD problems
Wear cotton clothing, not polyester or other synthetics
Leave all ESD-sensitive components in their anti-static packaging
until you actually install them
Ground yourself using a wrist strap with a series 1megohm resistor
(do NOT ground yourself directly--this poses a shock hazard)
Use an anti-static mat
Use a grounded soldering iron. When soldering ICs and transistors,
you should also keep the chassis and PC boards grounded using
jumper clips. Grounding to the soldering iron's temperature control
box is acceptable.
Sockets are used for only a few of the ICs, including the
microprocessor and display driver. You should not use sockets for the
other ICs, because they tend to be unreliable and can cause problems in
some circuits due to the added lead length.
Since sockets are not used in most cases, you must carefully verify the
type and orientation of each IC before soldering. IC removal and reinstallation is to be avoided since damage to the IC or the PC board
may occur.
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K2 Manual 1/24/99 V.XC ©1999 Elecraft
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4. Control Board
The control board is the “brain” of the K2. It monitors all signals
during receive and transmit, and handles display and control functions
via the front panel board. The microprocessor, analog and digital
control circuits, automatic gain control (AGC), and audio amplifier are
located on this board.
Components
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Review the precautions described in the previous section
before handling any IC’s or transistors. These components can be
damaged by static discharge, and the resulting problems are often
difficult to troubleshoot.
Open the bag of components labeled CONTROL and sort the
parts into groups (resistors, diodes, capacitors, etc.). If any of the
components are unfamiliar, identify them using the illustrations in the
parts list, Appendix A. Doing a components inventory is optional.
Locate the control board. It is the smallest of the three K2 PC
boards, labeled “K2 CONTROL” on the front side, in the lower righthand corner. The lower left-hand corner is notched.
Open the bag labeled MISCELLANEOUS and empty the
contents into a small, shallow box or pan. This will prevent loss of any
of the small hardware, while still allowing you to locate items as
needed.
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The Allen wrenches are located in a small bag with the
MISCELLANEOUS items. These wrenches may have been oiled
during manufacturing. Remove the wrenches and wipe off the oil, if
any, then discard the bag.
Field Test Notes: Two different sizes of small crimp pins were
inadvertently purchased for the field test kits. Two of the pins are for
the speaker connector, and the other three--which are different--are for
the test probes (counter and voltmeter). The test probe crimp pins (3)
and housings (2) are bagged separately and labeled PROBES.
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There are four sizes of black-anodized, 4-40 machine screws
provided with the kit. The relative sizes of the screws are shown below
for identification purposes (not to scale). The 3/16” (4.8mm) pan-head
screws are the most numerous, and will be referred to as chassis screws
throughout the manual. There is only one Flat-head 3/16” (4.8mm)
screw in the kit.
K2 Manual 1/24/99 V.XC ©1999 Elecraft
Flat-head, 3/16” (4.8mm)
Pan-head, 3/16” (4.8mm)
(chassis screws)
Pan-head, 3/8” (9.5mm)
Pan-head, 1/2” (12.7mm)
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color codes easier to read if you need to re-check the values after
installation.
Note: When multiple items appear on one line in a component list such
as the one below, complete all items on one line before moving on to the
next, as indicated by the small arrow. (In other words, install R5 first,
then R2, then go to the second line.)
__ R5, 33k (ORG-ORG-ORG) ⇒ __ R2, 3.3M (ORG-ORG-GRN)
__ R3, 33k (ORG-ORG-ORG)
__ R6, 470 (YEL-VIO-BRN)
__ R7, 1.96K, 1% (BRN-WHT-BLU-BRN)
__ R8, 100, 1% (BRN-BLK-BLK-BLK)
__ R9, 806K, 1% (GRY-BLK-BLU-ORG)
__ R10, 196K, 1% (BRN-WHT-BLU-ORG)
Assembly
__ R16, 10 (BRN-BLK-BLK) ⇒ __ R17, 10M (BRN-BLK-BLU)
__ R19, 1.5k (BRN-GRN-RED) __ R18, 1.5k (BRN-GRN-RED)
__ R21, 10k (BRN-BLK-ORG)
__ R20, 2.7ohms (RED-VIO-GLD)
All of the components to be installed are on the top (component side) of
the control board. On the bottom of the board there is an outline for the
audio filter board and its two connectors (J1 and J2), but these items
are not part of the basic K2 kit.
Solder all of the resistors, then trim the leads as close as possible to
the solder joints. (If the leads get in the way during soldering, try
soldering and trimming a few leads at a time.)
With the top side of the PC board facing you (notch at the lower
left), locate the position of resistor R1, near the upper-left corner. The
label “R1” appears just below the resistor’s outline.
Install a 100k resistor (brown-black-yellow) at R1, with its first
color band (brown) at the top. Make sure it is seated flush with the
board, then bend the leads on the bottom to hold it in place. Do not
solder this resistor until the remaining fixed resistors have been installed
in the next step.
Install the remaining fixed resistors, which are listed below in leftto-right PC board order. The resistors should all be oriented with the
first significant-digit band towards the left or top. This will make the
Locate RP6, a 10K, 10-pin resistor network (labeled
“10A3.103G”). (“RP” means “resistor pack,” another name for resistor
networks.) Note that one end of the resistor network has a dot,
indicating pin 1.
Locate the component outline for RP6 at the left end of the PC
board. Install the resistor network so that the end with the dot is lined
up with the “1” label.
Make sure the resistor network is seated firmly on the board, then
bend the leads at the far ends in opposite directions to hold it in place.
(It is not necessary to clip the leads.) Do not solder RP6 yet.
K2 Manual 1/24/99 V.XC ©1999 Elecraft
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Resistor networks and other components with many leads are
difficult to remove once soldered. Double-check the part numbers and
orientation before soldering.
Install the remaining resistor networks in the order listed below.
Do not solder them until the next step.
__ RP1, 3.9k, 10 pins (10A3.392G)
__ RP7, 33k, 8 pins (8A3.333G)
__ RP2, 82k, 8 pins (77083823)
__ RP3, 47k, 10 pins (10A3.473G)
__ RP5, 470, 10 pins (10A3.471G)
__ RP4, 82k, 8 pins (77083823)
Solder all of the resistor networks.
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K2 Manual 1/24/99 V.XC ©1999 Elecraft
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Install the diodes listed below, beginning with D1, which is in the
upper left-hand corner of the PC board. (Refer to the parts list if
necessary to identify the different types of diodes.) If a diode has only
one band, the end with the band (the cathode) should be oriented
towards the banded end of the corresponding PC board outline. If a
diode has multiple bands, the widest band indicates the cathode end.
__ D1, 1N4148
__ D2, 1N4148
Install and solder the electrolytic capacitors listed below, which
are polarized. Be sure that the (+) lead is installed in the hole marked
with a “+” symbol. The (+) lead is usually longer than the (–) lead, and
the (–) lead is identified by a black stripe (Figure 4-1).
-
__ D3, 1N5817
Double-check the orientation of the diodes, then solder.
Install the small fixed capacitors listed below, beginning with C2
in the upper left-hand corner of the board. (This list includes all of the
fixed capacitors on the control board except the tall, cylindrical
electrolytic types, which will be installed later.) The list shows both the
value and the capacitor labels, using notation explained in the previous
section. After installing each capacitor, bend and clip the leads, but do
not solder until the next step.
Note: Remember to complete all items in each line before moving on to
the next. (Install C2, C3, and C4, then C7, etc.)
__ C2, .001 (102) ⇒
__ C7, 330 (331)
__ C9, .01 (103)
__ C5, .01 (103)
__ C11, .01 (103)
__ C19, .047 (473)
__ C23, .01 (103)
__ C26, 0.1 (104)
__ C34, .001 (102)
__ C35, .01 (103)
__ C41, .01 (103)
__ C3, .01 (103)
⇒
__ C6, .047 (473)
__ C10, .01 (103)
__ C14, .047 (473)
__ C16, .047 (473)
__ C21, 33 (33)
__ C27, .022 (223)
__ C24, .0027 (272)
__ C30, .047 (473)
__ C36, .0027 (272)
__ C37, .01 (103)
Solder all of the small fixed capacitors.
__ C4, 0.47 (474)
__ C8, 39 (39)
__ C12, .001 (102)
__ C17, .01 (103)
__ C18, .01 (103)
__ C20, .001 (102)
__ C25, 0.1 (104)
__ C31, 0.1 (104)
__ C40, .01 (103)
__ C39, .01 (103)
__ C38, 680 (681)
+
Figure 4-1
__ C1, 2.2µF
__ C28, 220µF
__ C32, 22µF
⇒
__ C13, 22µF
__ C29, 220µF
⇒
__ C15, 100µF
__ C33, 2.2µF
Install and solder ceramic trimmer capacitor C22. Orient the flat
side of this trimmer as shown on its PC board outline. Be sure that the
capacitor is seated flush with the PC board, then solder.
Using a small flat-blade screwdriver, set C22 to the mid-point in
its rotation. The screwdriver slot should be parallel to the outline of
crystal X2, just above C22 on the PC board.
i
The trimmer you just installed, C22, is used to calibrate the
master 4.000 MHz crystal oscillator, which determines the accuracy of
the built-in frequency counter and VFO. The standard setting given
above will suffice in most cases, but if you wish to more accurately
calibrate C22, refer to the Operation section under Advanced Operating
Features.
Locate Q12 (type PN2222A), which is a small, black TO-92
package transistor. Note: Q12 and other TO-92 transistors may have
either of the two shapes shown in Figure 4-2. In all cases the flat side of
the device should be aligned with the flat side of the component outline.
K2 Manual 1/24/99 V.XC ©1999 Elecraft
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will be eliminated with the next revision of the PC board by using the
solder mask to cover the pads on the top of the board.
Slip a crystal spacer over the leads of each crystal (X1 and X2).
Install crystals X1 and X2 so that they are flat against the board.
X1 is 5.068 MHz and is located near the notch in the lower left-hand
corner. X2 is 4.000 MHz, and is located near the center of the board.
Solder the crystals.
Figure 4-2
Install Q12 near the upper left-hand corner of the PC board. Align
the flat side of Q12 with its PC board outline as in Figure 4-2. The
body of the transistor should be about 1/8” (3mm) above the board;
don’t force it down too far or you may break the leads. Bend the leads
of the transistor outward slightly on the bottom to hold it in place.
Solder Q12.
The cases of the crystals should be grounded to minimize signal
radiation (Figure 4-3). Insert a 1” (25mm) length of bare, solid hookup
wire into the provided grounding hole and solder it on the bottom of the
board. Then fold the bare wire over the crystal and solder it to the top
of the can. (Don’t overheat the crystals or cover the entire top surface
of the crystal with solder; only a small amount of solder is required.)
X1
X2
Install the remaining TO-92 package transistors in the order listed
below.
__ Q12, PN2222A
__ Q2, 2N3906
__ Q5, 2N7000
__ Q8, PN2222A
__ Q11, PN2222A
__ Q1, 2N3906
__ Q3, 2N7000
__ Q4, 2N7000
__ Q6, J310
__ Q7, J310
__ Q9, MPS5179 __ Q10, MPS5179
Figure 4-3
i
Solder all of the above transistors.
i
When installing crystals, you must use the thin spacers
provided in the MISCELLANEOUS bag to keep the crystal cans from
shorting to their pads on the top of the board. The need for these spaces
The voltage regulators, U4 and U5, will be installed in the
following steps. These regulators have different output voltages and
must not be interchanged. Check the labels on the regulators carefully
before soldering; the basic part numbers should match those on the PC
board outline.
K2 Manual 1/24/99 V.XC ©1999 Elecraft
Install U4 (LM2930T-8) and U5 (LM7805), bending the leads as
indicated (Figure 4-4). Long-nosed pliers should be used because the
indicated bend location may be at the thicker part of the lead. After
inserting the leads into the proper holes, secure each IC with a 4-40 x
3/8” (9.5mm) machine, #4 lockwasher, and 4-40 nut. (Note: these
regulators may have either plastic or metal mounting tabs.)
18
Install the 2-pin male connectors, P5 and P6. As shown in Figure
4-5, the short end of the connector pins are inserted into the PC board.
P5, the voltmeter input connector, can be found near the upper left-hand
corner of the board. P6 is used for frequency counter input, which is in
the upper right-hand corner.
2-pin
connector
Bend pins
down 90°
Top side of
PC Board
Figure 4-4
Figure 4-5
Solder the voltage regulator ICs.
Install a 40-pin IC socket at U6. (The microprocessor will be
inserted into the socket in a later step.) Orient the notched end of the
socket to the left as shown on the PC board outline. Bend two of the
socket’s corner leads slightly to hold the socket in place, then solder
only these two pins. If the socket does not appear to be seated flat on
the PC board, reheat the solder joints one at a time while pressing on
the socket.
Solder the remaining pins of the 40-pin socket.
i
Install the 10-pin, dual-row connector, P4. It is located to the left
of P5. It must be seated flat on the board before soldering.
Install S1, the miniature slide switch, to the right of P5.
At the upper left and right corners of the board you’ll find two
short jumpers, each labeled with a ground symbol ( ). These jumpers
are provided for connecting clip leads during alignment and test. Form a
3/4 (19mm) length of bare copper hookup wire into a “U” shape for
each jumper (Figure 4-6). (You can use a clipped component lead as an
alternative to hookup wire.) Solder the jumpers on the bottom of the
board.
The connectors used in the following steps have plastic bodies
that can may melt if too much heat is applied during soldering, causing
the pins to be mis-positioned. Limit soldering time for each pin to 3
seconds maximum (1 to 2 seconds should be adequate).
Figure 4-6
K2 Manual 1/24/99 V.XC ©1999 Elecraft
19
i
Top side of
PC Board
The three multi-pin connectors along the bottom edge of the
board (P1, P2 and P3) must be positioned and soldered carefully.
Incorrect alignment of these connectors may cause instability or
intermittent operation, and it is very difficult to remove them once they
are soldered.
Install 6-pin right-angle connector P1 as shown in the side view
below (Figure 4-7). Do not solder it until the next step. The plastic part
of the connector must be seated flat against the PC board, and the pins
must be parallel to the board. Do not bend or trim the pins on the
bottom of the board.
P3
Figure 4-8
Install P2, a 36-pin, dual-row, right-angle connector. Use the same
method you used for P1 and P2.
Top side of
PC Board
P1
Figure 4-7
Solder just the two end pins of P1, then examine the placement of
the connector closely. If P1 is not flat against the board, re-heat the
solder on the end pins one at a time while pressing firmly on the
connector. Once it is in the right position, solder the remaining pins.
Install P3, a 20-pin, dual-row right-angle connector (Figure 4-8).
Use the same method you used for P1. Do not solder P3 until you are
sure that it is seated properly.
Locate U2, an 8-pin IC, part number LM833. (LM833 is the basic
part number; there may be an additional prefix or suffix as well as
other markings.) This and all remaining ICs on the control board are
Dual-Inline Packages, or DIPs. Referring to Figure 4-9, identify the
notched or dimpled end of the IC.
Notch
Pin 1
Dimple
Pin 1
Figure 4-9
K2 Manual 1/24/99 V.XC ©1999 Elecraft
20
Install U2 in the orientation shown by its PC board outline, near
the upper left-hand corner of the PC board, but do not solder it yet.
Make sure the notched or dimpled end is lined up with the notched end
of the PC board outline. Even though the outline is covered when the IC
is installed, you can still verify that the IC is installed correctly by
looking at pin 1. The PC board pad corresponding to pin 1 will be
either oval or round, while the other pads are all rectangular or square.
Prepare the pins of the microcontroller, U6 (Figure 4-10). The two
rows of pins must be straight and parallel to each other to establish the
proper pin spacing for insertion into the socket. To straighten the pins,
hold the microcontroller’s body at each end, then rest one entire row of
pins against a hard, flat surface. Gently press down on the pins and
rock the IC forward to bend the pins into position.
i
You may overheat the IC pins or PC pads if you take an
excessive length of time to solder. After a few tries, you should be able
to solder an IC pin in about 1 or 2 seconds. If it seems to be taking
longer, or if your solder joints are not shiny and smooth, review the
recommendations on soldering irons and solder in the previous section.
Bend two of U2’s corner pins out slightly on the bottom of the
board to hold the IC firmly in place, flat against the top of the board.
Find pin 1 and verify that its pad is either round or oval. Once U2 is
properly seated, solder all eight pins.
Install the remaining ICs in the order listed. Bend the pins to hold
each IC in place as you did with U2, but do not solder until the next
step. The notched or dimpled end of each IC must be aligned with the
notched end of its PC board outline.
__ U1, NE602
__ U8, MAX534
__ U3, LM6482
__ U9, LM380
__ U7, 25LC160
__ U10, LMC660
Verify the location of pin 1 on each IC by looking at the associated
PC board pads, as before. Then solder all of the ICs.
Flared
Straight
Figure 4-10
i
When the microcontroller is installed in the next step, you must
be careful to avoid bending its pins. Make sure that all pins are lined up
with the associated holes in the socket before pressing down on the IC.
Watch the pins on both rows as you press down, realigning them with
the socket holes individually if necessary.
Insert the microcontroller, U6, into its socket. Make sure that pin 1
on the IC itself is lined up with the pin 1 label near the lower left-hand
corner of the PCB outline.
K2 Manual 1/24/99 V.XC ©1999 Elecraft
Visual Inspection
Nearly all problems with kits are due to incorrectly installed
components or poor solder joints. You can avoid these problems by
doing a simple visual inspection; a few minutes spent here may save
you hours of troubleshooting time or repair charges.
Make sure there are no components installed backwards. Check all
diodes, resistor networks, electrolytic capacitors, and ICs.
Examine the bottom of the PC board carefully for the following:
§
§
§
cold solder joints
solder bridges
unsoldered pins
Resistance Checks
While the control board will be fully tested in a later section, you
should perform the resistance checks listed below to insure that there
are no shorts or opens in the most critical circuits.
[Resistance check table TBD]
21
K2 Manual 1/24/99 V.XC ©1999 Elecraft
22
5. Front Panel Board
The front panel includes all of the control and display devices that
you’ll use when operating the K2, including the liquid-crystal display
(LCD), LED bargraph, push-button switches, and potentiometers.
These user-interface (UI) elements are controlled by the microcontroller
on the control board.
Components
See Appendix D for photos of the front panel assembly.
Locate the front panel PC board, which is just a bit larger than the
control board. It is labeled “K2 FP” on the top side, in the lower righthand corner.
The hole in the board at the lower left is for the headphone jack, which
is mounted on the RF board, not the front panel. The hole at the lower
right is for the power switch, which is also mounted on the RF board.
Some components are installed on the bottom of the board. The
connector on the bottom (at the bottom edge) is J1, which connects the
front panel board to the RF board. There are also two standoffs on the
bottom that provide increased mechanical stability by allowing the front
panel and control boards to be secured together.
Some of the assembly steps for this board are similar or identical to
those for the control board. The instructions for such steps will be
presented more briefly here, but you can refer back to the previous
section if necessary.
Open the bag labeled FRONT PANEL and sort the parts into
groups (resistors, diodes, capacitors, etc.). Observe anti-static
precautions when handling ICs and transistors.
Assembly
i
Please pay close attention to all front-panel assembly steps.
Your K2’s appearance and operation will be adversely affected if the
controls or display are not mounted correctly. Some components must
be mounted before others, so you must adhere to the indicated assembly
sequence. There are also special instructions for installing components
on the bottom of the board.
Install the following 1/4-watt fixed resistors, which are listed in
left-to-right PC board order. Solder the resistors after all have been
installed. (Note: R13 and a few other components in its vicinity are
part of the SSB adapter option, and are not included in the basic K2 kit.
A check-list of these components is provided at the end of this section.)
__ R12, 120 (BRN-RED-BRN) ⇒ __ R10, 33 (ORG-ORG-BLK)
K2 Manual 1/24/99 V.XC ©1999 Elecraft
__ R9, 220 (RED-RED-BRN)
__ R6, 4.7k (YEL-VIO-RED)
__ R14, 100k (BRN-BLK-YEL)
__ R11, 470 (YEL-VIO-BRN)
__ R7, 4.7k (YEL-VIO-RED)
23
K2 Manual 1/24/99 V.XC ©1999 Elecraft
24
Flip the board over and install the following resistors on the
bottom of the board. Solder them on the top side.
__ R16, 15k (BRN-GRN-ORG)
__ R15, 10k (BRN-BLK-ORG)
There are two ground jumpers on the front panel board, one at the
far left and the other at the lower right, labeled “GND.” Form a 3/4”
(19mm) length of bare copper hookup wire into a “U” shape for each
jumper, then solder.
When you install the resistor networks in the next step, you
must align the dotted end of the network with the pin 1 label on the PC
board outline. If these networks are installed backwards you may
damage one or more front-panel components.
Flip the board over and install a 40-pin IC socket at U1. (U1, the
LCD driver, will be inserted into this socket in a later step.) Orient the
notched end of the socket to the left as shown on the PC board outline.
Make sure the socket is seated flat on the PC board before soldering,
using the technique described in the previous section.
Install the resistor networks listed below. Double-check the
orientation and values before soldering.
Install the following ICs. Before soldering, verify that the ICs are
oriented correctly (pin 1 associated with a round or oval pad).
__ RP2, 120, 10 pins (770101121)
__ RP1, 100K, 10 pins (10A1.104G)
__ U4, TPIC6B595
i
__ U3, TPIC6B595
__ U2, 74HC165
i
Install and solder the diodes listed below, observing proper
orientation as described in the previous section.
__ D4, 1N5817
__ D5, 1N5817
__ D6, 1N5817
Install and solder the following capacitors. C9 is located on the
bottom of the board and is soldered on the top side.
__ C1, .047 (473)
__ C2, .01 (103)
The bargraph LED will be installed in the following two steps.
This component must be seated flat on the PC board or it will interfere
with final front panel assembly. Also, any misalignment will be visible
from the front of the K2.
__ C3, .047 (473)
__ C9, .01 (103), on bottom
Install PN2222A transistors at Q1 and Q2, near the middle of the
board, and solder. These transistors must be mounted so the lead length
above the PC board is less than 1/8” (3mm) to prevent them from
hitting the front panel.
Locate the bargraph LED, DS2, which has a beveled corner or
edge that indicates pin 1. Install DS2 as shown on its PC board outline,
just to the left of the LCD. Bend two opposite corner pins slightly to
hold it to the board, the solder only these two pins.
If the bargraph is not perfectly flat against the PC board, re-heat
the solder on the corner pins alternately while pressing it down. Once it
is in the correct position, solder the remaining pins.
K2 Manual 1/24/99 V.XC ©1999 Elecraft
Remove any hardware supplied with the microphone jack, J2; the
nut and washer will not be used.
Install the microphone jack (J2) in the lower left-hand corner of the
board, with its polarizing nub at the top (Figure 5-1). Press the jack
down until it is completely flat against the PC board. Re-check the
orientation of the polarizing nub before soldering.
Polarizing
nub
25
Install another 3/16” (4.8mm) diameter x 1/4” (6.4mm) long round
standoff on the top of the PC board, on the left side of the large square
hole in the middle of the board. The standoff mounting hole is just
below C2. Use the same hardware as indicated in the previous step.
Install two 1/4” (6.4mm) diameter x 1/2” (12.7mm) long hex
standoffs on the bottom of the board. The mounting holes for these
standoffs are indicated by large pads on the top and bottom. Use a #4
lockwasher between each standoff and the PC board, and secure each
with a 3/8” (9.5mm) screw.
There are two types of potentiometers supplied with the front
panel. Four of them are marked “10K” and one is marked “5K.”
Locate the 5k potentiometer, and install it at R3, in the lower left-hand
corner. Make sure that the potentiometer body is parallel to the PC
board and is pressed against the board as far as it will go before
soldering.
Figure 5-1
Install two 3/16” (4.8mm) diameter x 1/4” (6.4mm) long round
standoffs on the top of the board, adjacent to the microphone jack
(Figure 5-2). Secure the standoffs from on the bottom side with chassis
screws and #4 lock washers. Recall that “chassis screw” is short-hand
for 3/16” (4.8mm) long pan-head machine screws.
Figure 5-2
Install the four 10k potentiometers at R1, R2, R4, and R5. Verify
correct positioning as you did in the previous step.
K2 Manual 1/24/99 V.XC ©1999 Elecraft
The front panel attaches to the RF board via J1, a 20-pin singlerow female connector. Flip the board over and install J1 on the bottom
of the board (Figure 5-3), soldering just two pins at either end.
26
Top of
board
Approx.
.05-.06”
Bottom side of
PC Board
J1
Figure 5-3
Re-heat the two end pins and press the connector down as needed
until J1 is seated flat against the board, then solder the remaining pins.
There are 16 pushbutton switches on the front panel, S1-S16,
which must be seated at exactly the right height to prevent an uneven
appearance (Figure 5-4). Start by installing the switches as indicated on
their PC board outlines, but do not solder them yet. (Note: the
switches have two pairs of pins at each end. The pairs are
interchangeable; either pair can be up or down.)
Figure 5-4
Each switch should be seated as indicated in Figure 5-4, with its
pins just barely protruding from the bottom of the board and its body
1/16” (1.5mm) above the board. Press each switch carefully as far
down as it will go without bending the leads. The “knee” in each switch
pin will end up just above the board as shown.
Look over all switches from the edges of the board to confirm that
they are all at the same height. Once you’re satisfied that they are
seated correctly, solder all of the switches. Since the leads do not
protrude from the bottom of the board, be sure that some solder flows
into the holes and around the leads.
K2 Manual 1/24/99 V.XC ©1999 Elecraft
Install rectangular gray key caps on S1 and S3 so that the key caps
are parallel to the long axis of the PC board (Figure 5-5). The caps are
installed simply by pressing them onto the switch plungers.
Gray keycaps
27
end. (Do not remove the diffuser backing, which is glued to the bottom
surface of the diffuser.)
Place one 1/8" (3mm) tall by 1/8" (3mm) diameter plastic standoff
on each of the four LED pins.
Position the backlight assembly between the two pairs of mounting
holes labeled D2 and D3 as shown in the two views of Figure 5-6. The
diffuser must be parallel to and 1/8" (3mm) above the PC board. Bend
the LED leads slightly to hold the assembly in place.
Square Keycap
Figure 5-5
Install a square black key cap on S7 as shown above.
Install rectangular black key caps on the remaining 13 switches.
Straighten the pins of U1, the LCD driver (PCF8566), as you did
with the microcontroller on the control board.
Insert U1 into its socket on the bottom of the board. (This must be
done before continuing with LCD installation, since the LCD’s
presence will make pressing U1 into its socket much more difficult.) Be
sure that U1 is completely seated and that no pins are bent.
i
The LEDs in the LED backlight assembly are somewhat
fragile. Verify that the LEDs are pressed into the diffuser and are not
loose.
Locate the LED backlight assembly, which is in a small bag with
the other FRONT PANEL components. Carefully remove its
protective covering, a thin sheet glued to the top of the diffuser at each
Figure 5-6
Examine the backlight/diffuser assembly closely to insure that it is
parallel to the front panel board and seated as far down on the board as
it will go (exactly 1/8" [3mm] above the board).
Once the backlight/diffuser assembly is in its correct position-supported by the plastic spacers and parallel to the PC board--solder
the four LED pins. If the assembly is not flat against the boards, re-heat
the LED pins one at a time and press it into place.
K2 Manual 1/24/99 V.XC ©1999 Elecraft
28
establish the correct spacing from front panel to control board and
provide some vibration resistance.
i
Caution: The LCD and its pins are fragile—handle carefully.
Do not remove the protective plastic film from the surface of the LCD
until later in this section when the front panel assembly is completed.
Pad
Remove the LCD from its packing materials, being careful not to
bend the pins.
Pad
Top Edge
(Back of PC Board)
The LCD has six pins along the bottom edge (three on each side),
and 24 pins along the top edge. Locate these holes on the top of the PC
board and place the LCD in it proper position as shown in the edge
view below (Figure 5-7), but do not solder yet.
Figure 5-8
Uninstalled Components
LCD
Figure 5-7
The LCD must be seated flat against the diffuser as shown in
Figure 5-7, and the diffuser must in turn be parallel to the board. If it
does not appear to be seated correctly, it may be because the backlight
LEDs or spacers are mis-aligned. When the entire assembly is installed
correctly, the LCD’s pins will just barely protrude from the bottom of
the board.
Solder the four corner pins of the LCD, then re-check the
alignment of the LCD assembly. If everything looks correct, solder the
remaining pins.
Attach two 1/4” (6.4mm) dia. self-adhesive rubber pads to the
bottom of the front panel board in the positions indicated in Figure 5-8.
The pads should be attached as close as possible to the top and side
edges of the board, but should not hang over on any edge. These pads
At this point you should have several component locations that are not
filled. These locations are for parts that are provided with the SSB
adapter, which should not be installed until after the basic K2 kit is
completed and tested. Full instructions are included with the SSB
adapter kit.
Check off each of the components in the list below, verifying that
they are not installed. You should have no other uninstalled components
except for Z1, the optical encoder.
__ C4, .01
__ C5, .01
__ C6, .01
__ C7, .01
__ C8, .01
__ R13, 68k, 1%
__ RP3, 10k resistor network
__ Q3, 2N3906
__ P1 (on the bottom of the board)
Visual Inspection
Make sure there are no components installed backwards. Check all
diodes, resistor networks, electrolytic capacitors, and ICs.
Examine the bottom of the PC board carefully as you did with the
control board.
K2 Manual 1/24/99 V.XC ©1999 Elecraft
29
K2 Manual 1/24/99 V.XC ©1999 Elecraft
Resistance Checks
Perform the resistance checks listed below to insure that there are no
shorts or opens in the most critical circuits. (The front panel board will
be fully tested in a later section.)
[Resistance checks TBD]
30
Turn the front panel face up. Position the clear plastic LCD bezel
over the LCD hole, then secure it with four 2-56 screws (fillister head,
stainless steel) as shown in Figure 5-10. Tighten the 2-56 screws only
the amount needed to hold the bezel to the front panel. Overtightening may crack the bezel or strip the threaded holes in the
panel.
E
L EC R A F T
K 2
T R A NS C E I V ER
Front Panel Final Assembly
Place the front panel chassis piece in front of you, face-down.
Placing it on a soft cloth will protect the finish and labeling. The large
round microphone jack hole should be on the right.
Position the green plastic filter over the inside of the bargraph
LED hole (Figure 5-9). The hole is rectangular, 1” x 1/4” (25 x
6.4mm). Secure the filter to the panel using two small strips of
electrician’s tape or other durable tape.5 Do not use thick, double-sided
tape since this may interfere with proper positioning of the bargraph
LED when the panel is installed.
Green Film
Tape
Figure 5-1
5
Field test note: we may include specialized tape in the future.
2-5 Scre
6
(w) 4
Figure 5-2
LC
BD
el
z
e
K2 Manual 1/24/99 V.XC ©1999 Elecraft
i
The optical shaft encoder, Z1, will be connected to the bottom
of the PC board by four short wires. The wires must be installed first in
order to position the encoder correctly.
Prepare four 1.5” (38mm) lengths of bare, solid hookup wire.
31
Insert the front panel PC board into the front panel. The
pushbutton switch caps on both sides of the LCD should protrude
slightly as shown in the side view, Figure 5-4a.
Note: the board/panel assembly will not be rigidly held in place until it
is mated with the RF and control boards in a later section.
Install the bare wires from on the bottom of the board, using the
four pads below the large rectangular hole (Figure 5-11). The wires
must be soldered and trimmed on the top of the board. Set the board
aside for now. The wires will be connected to the encoder in a later
step.
(b)
(a)
Figure 5-4
Figure 5-3
Remove the protective plastic film from the face of the LCD. Be
careful not to scratch the glass.
A 1/4” (6.4mm) standoff on the PC board should now be visible
through the hole just to the left of the encoder mounting hole. Secure the
panel to this standoff using a 4-40 x 3/16” (4.8mm) flat-head screw as
shown in Figure 5-4b.
K2 Manual 1/24/99 V.XC ©1999 Elecraft
32
Remove the hardware from the shaft of the optical encoder, Z1.
Insert the encoder through the hole in the front panel board (Figure
5-5a).
Attach the encoder to the inside of the front panel using the
hardware provided. Figure 5-5 shows the side view (a) and front view
(b) with encoder properly installed. The encoder has a small metal tab
near the shaft that will only allow it to be installed one way. Do not
over-tighten the finishing nut. (Note: the green encoder bushing is
metal, not plastic.)
Set all potentiometers to approximately midway in their rotation
(12 o’clock).
Note: When attaching knobs in the next step, you may find it easier to
install knobs on the KEYER and POWER controls first.
Attach five small knobs to the potentiometer shafts using the
smaller of the two Allen wrenches (.050”, 1.3mm). The white line on
each knob should be lined up with the center line of its shaft. The knobs
should be mounted as close as possible to the panel without rubbing.
Locate a 1” (25mm) diameter by 1/16” (1.6mm) thick felt washer
(in the MISCELLANEOUS items). Place the washer over the
encoder’s finishing nut (Figure 5-6). The washer should be seated
directly on the front panel, with the nut completely inside it.
(b)
(a)
Figure 5-5
Attach the four encoder wires you installed earlier to the matching
pins on the back of the encoder. Each wire should be wrapped securely
around its pin, with no slack in the wire. Trim and solder all four wires,
making sure that none of the wires are shorting to each other or to the
encoder body, which is conductive.
Figure 5-6
Place the large knob on the encoder shaft. Push the knob on until it
just touches the felt washer, then tighten one set screw using the larger
Allen wrench (5/64”, 2mm). If the knob does not spin freely, loosen the
K2 Manual 1/24/99 V.XC ©1999 Elecraft
set screw and move the knob out slightly. If the knob is not contacting
the felt washer at all, it may “drift” slightly.
Tighten both set screws.
33
K2 Manual 1/24/99 V.XC ©1999 Elecraft
34
6. RF Board
Most of the K2’s receiver and transmitter circuits are located on the RF
board, including filters, oscillators, and RF amplifiers. The front panel
and control boards plug into the RF board, and the chassis pieces are
designed to form a tight enclosure around it (see photos in Appendix
D). In addition, many option boards plug directly into the RF board to
minimize wiring.
Assembly and testing of the RF board is broken into three parts:
Part I: The DC and control circuits are installed so that the front panel
and control boards can be plugged in and tested. The I/O controller (U1
on the RF board) is also installed and tested at this time. Once this
phase of assembly is completed, you’ll have the K2’s built-in test
equipment available for testing and aligning the remaining circuits.
Part II: Synthesizer and receiver components are installed and tested.
By the end of Part II you’ll have the K2 receiving on 40 meters.
Part III. Transmitter components and all remaining filter components
are installed. The K2 is then aligned on all bands.
Components
i
Review anti-static precautions before handling transistors or
ICs.
Open the bag labeled RF and sort the components into related
groups. In later steps you’ll sort some of the components according to
value to reduce the likelihood of assembly errors.
Locate the RF board and place it in front of you with the
component side up (the side with most of the parts), and the front edge
facing you (the edge with the irregular cutouts). Throughout this section
we’ll refer to the different areas of the board in terms of their proximity
to you. For example, “front-left” means the corner closest to you on the
left.
K2 Manual 1/24/99 V.XC ©1999 Elecraft
Take a moment to familiarize yourself with the RF board using
Figure 6-1 to identify the major sections. If you flip the board over
you’ll see that there are a few components on the bottom of the board,
primarily in the transmitter section.
XMTR
fastener from the top side of the board with two chassis screws and two
#4 lock washers.
Holes offset to the
left of center
T-R Switch
Band-Pass
Filters
35
Low-pass
Filters
Figure 6-1
U1 (I/O Controller)
Synthesizer
(Back of board)
RCVR
2-D Fasteners
(5)
Figure 6-1
1/4"
Standoffs
Assembly, Part I
Locate a 2-D fastener and hold it vertically as shown in Figure 6-2.
Looking at a side with two holes, note that the holes are offset from the
center. When you install the fasteners in the following step, be sure to
sure to position them so that the holes in the fastener are shifted in the
same direction as the holes in the PC board outlines on the bottom of
the board.
Turn the board over and install 2-D fasteners at five locations on
the bottom of the RF board as shown in Figure 6-3. Secure each
Figure 6-2
K2 Manual 1/24/99 V.XC ©1999 Elecraft
Make sure that 2-D fasteners on the edges line up with the edge of
the PC board and do not hang over. If they hang over or do not match
their component outlines, they are installed backwards.
Install two 3/16” (4.8mm) diameter by 1/4” (6.4mm) long round
standoffs on the bottom of the board (see Figure 6-3). Secure these
standoffs from the top side with chassis screws and #4 lock washers.
Turn the board back over to the top side. Install the 28-pin IC
socket at U1, near the middle of the board (Figure 6-1). The notched
end of the socket should be at the left. Make sure the socket is flat
against the PC board before soldering. (U1 itself will be installed in a
later step.)
i
In the following steps you will install the latching relays (K1K17). Relay pins must not be bent, even after placement on the PC
board, as this may cause unreliable mechanical operation. Since the
pins cannot be bent to hold the relays on the board, an alternative
assembly technique using a flat surface must be used. For this
technique to work, the relays must be installed before any of the taller
components.
Place relays K1-K17 on the top side of the RF board. One end of
each relay has a heavy line printed across the top to indicate the pin 1
end. This end must be matched with the same end of the relay’s PC
board outline. Do not solder the relays yet.
When all of the relays have been placed on the board, lay a flat
object such as a book or piece of cardboard on top of the relays to keep
them in place, then flip the board over.
Solder only two pins (at opposite corners) on each relay. Do not
bend or clip relay leads.
Turn the board back over and verify that all of the relays are in the
correct orientation and are seated flat on the board.
36
Solder all of the remaining relay pins.
Install R1 and R2 (1K, BRN-BLK-RED), near the back left
corner of the board.
Install C1 and C2 (.001µF), which are on the left edge.
Install electrolytic capacitors C105 and C106 (2.2µF), located
near the front-left corner.
Install R35 and R36 (82, GRY-RED-BLK) just to the right of
C105.
Install R115 (.05, 3 watts) at the front right corner of the board.
Form the leads as indicated by the component outline.
Install the following components to the left of R115.
__ C111, 2.2µF electrolytic
__ R113, 82 (GRY-RED-BLK)
__ Q23, 2N7000
Install the internal speaker connector, P5, which is near the on-off
switch (S1). Position the connector as shown by its component outline,
with the vertical locking ramp towards the front of the PC board.
Install diode D10 (1N5821), which is located on the right edge of
the board.
Install the following capacitors near D10:
__ C77, .001 (102)
__ C196, .047 (473)
K2 Manual 1/24/99 V.XC ©1999 Elecraft
Install the key jack, J1, at the back-left corner of the board. Before
soldering, make sure that the jack is aligned with its PC board outline.
Install the headphone jack, J2, on the small board extension near
the front left corner. The pins on J2 are not very long, so they will be
nearly flush with the bottom of the board. Solder the pin closest to the
front edge first (ground), then verify that the jack is seated flat on its
plastic nubs before soldering the remaining pins.
Install the power switch, S1, at the right front corner. (The key
cap will be installed later.)
37
i
In the steps that follow you’ll install the connectors that mate
with the control and front panel boards. These connectors must be
installed properly to insure reliable mechanical connection. They are
very difficult to remove once installed, so follow all instructions
carefully.
Install the 6-pin, single-row female connector, J6, which is just left
of the power switch. It must be seated vertically on the board and must
not be tilted (Figure 6-4). Solder just one pin near the center of J6.
Install the DC input jack, J3, at the back right corner.
J6
Install the antenna jack, J4 (BNC), just to the left of J3. (Note:
On the revision XC RF board, the holes for J4 may be a very tight fit.)
Install the following components near U1 (at the middle of the
board). Note: You may need to confirm the part number on U2 (78L06)
with a magnifying glass, since it is easy to confuse it with U8 (78L05).
__ U2 (78L06)
__ C140, .001 (102)
__ C139, 0.1 (104)
__ R64, 470 (YEL-VIO-BRN)
Install the ceramic resonator, Z5, just below U1. (The ceramic
resonator looks like a capacitor with three pins.)
Figure 6-3
If J6 does not appear to be completely flat against the board, reheat the soldered pin and press down. Once it is installed correctly,
solder the remaining pins.
Install the 20-pin, dual-row female connector, J8, near the front
left corner of the board. Use the same technique you used for J6. This
connector must be seated flat on the board before soldering.
Install 36-pin dual-row female connector J7 in the same manner as
J6 and J8.
K2 Manual 1/24/99 V.XC ©1999 Elecraft
Flip the board over and install 20-pin male right-angle connector
P1 on the bottom of the board (Figure 6-5), but do not solder P1 yet.
The short ends of the bent pins are inserted into the holes, and the long
ends must be parallel with the board.
Front edge of
PC Board
38
Flip the board over. You’ll find two additional ground jumpers on
the bottom side, one near the middle of the board and the other near the
back edge. Install U-shaped ground jumpers in these two locations.
Install the I/O controller, U1 (PIC16C72), in its socket (near the
middle of the board). Be sure to align the notched or dimpled end of U1
with the notched end of the socked (to the left). Make sure U1 is seated
as far down in the socket as it will go and that none of its pins are bent.
Examine the RF board carefully for unsoldered pins, solder
bridges, or cold solder joints.
P1
Figure 6-4
Solder just the two end pins of P1.
Look closely at P1 to make sure that its plastic support is pressed
down as far as it will go, and that the pins are parallel to the board. If
not, re-heat the soldered ends while pressing it into place. Once it is
seated properly, solder the remaining pins.
To the left and right of the I/O controller, U1, you’ll find two short
jumpers labeled "GND" (on the top side of the board). Make and install
ground jumpers as you did on the control and front panel boards, using
3/4” (19mm) lengths of bare hookup wire.
Set switch S1 on the RF board to the “OFF” position. (Plunger
OUT is OFF, plunger IN is ON.)
Perform the following resistance checks to insure that there are no
shorts in critical areas of the RF board:
[resistance checks TBD]
K2 Manual 1/24/99 V.XC ©1999 Elecraft
39
i
When working with the side panels in the following steps, you
may wish to place a soft cloth or piece of cardboard on your work
surface to protect the paint.
Locate the two side panels, which are mirror images of each other,
and arrange them as shown in Figure 6-5. The outside surface of each
panel is completely painted. The hardware to be attached in the next
step goes on the inside surface, which has a bare aluminum area at the
bottom edge.
Holes offset
away from
panel
Install three 2-D fasteners on each side panel at the locations
indicated in . Use one chassis screw to hold each fastener to the side
panel (see Figure 6-7). The two unused holes on each fastener must be
offset away from the side panel.
Figure 6-6
Left Side Panel
(inside surface)
Right Side Panel
(inside surface)
Figure 6-5
K2 Manual 1/24/99 V.XC ©1999 Elecraft
i
Since the K2 chassis is made up of a number of individual
panels and fasteners, you may need to loosen the fasteners and readjust
them once or twice during assembly.
Attach the side panels to the RF board using two chassis screws
per side panel. The side panels are attached to the 2-D fasteners that are
already in place on the RF board. Figure 6-8 shows the approximate
location of the two screws used to secure the right side panel.
40
The tilt stand is located with the MISCELLANEOUS items. It
has three components: two oval feet and a tilt bail (Figure 6-9). Each
oval foot has a notch into which the bail will be inserted. Install one of
the oval feet on the bottom cover using 3/8” (9.5mm) 4-40 screws, #4
lock washers, and 4-40 nuts. The notch in the foot should be facing
inwards (towards the other foot).
Install the tilt bail, then the second oval foot. The bail should be
compressed firmly between the two feet. You may need to adjust the
positions of the feet slightly before tightening the hardware.
Make sure that the two feet are at exactly the same distance from
the front edge of the bottom cover. If they are not equally spaced, the
tilt stand may "rock" when in use.
Figure 6-2
Figure 6-1
K2 Manual 1/24/99 V.XC ©1999 Elecraft
41
Before the bottom cover is installed in the next step, make sure
that no component on the bottom of the board has an installed height of
over 1/4" (6.4mm). Capacitors that protrude above this height must be
bent downward at an angle to prevent them from hitting the bottom
cover.
Turn the RF board/side panel assembly upside down. Position the
bottom cover as shown in Figure 6-3 and secure it temporarily using at
least two chassis screws. Note: the heat sink and rear feet will not be
installed until Part III when the transmitter is assembled.
With the entire assembly still upside down or resting on one side
panel, plug the front panel assembly into the RF board (Figure 6-3).
Align the two assemblies so that connector J1 on the bottom of the front
panel PC board mates with P1 on the bottom of the RF board. The
arrow in Figure 6-3 shows the approximate location of P1 on the RF
board.
Once the front panel assembly is in place, the headphone jack (J2)
should be just flush with the front panel, and the front panel board
should be just touching the 2-D fasteners on the RF board. If this is not
the case, the front panel must be pushed farther in.
Secure the front panel to the side panels and RF board using 4
chassis screws. (Refer to the photos in Appendix D.) You may need to
make slight adjustments to the 2-D fasteners at the top edge.
Figure 6-3
K2 Manual 1/24/99 V.XC ©1999 Elecraft
Plug the control board assembly into the RF board, with the
component side of the control board facing backwards. (Refer to the
photos in Appendix D.) All three connectors on the control board must
be lined up with the three connectors on the RF board at all pins.
Make sure the control board is pushed as far down as it will go; it
should be flat against the RF board along its entire edge, with all three
connectors properly mated.
42
Once you have tried the control board extraction technique
described above, plug the control board back in for the tests that follow.
Secure the front panel and control boards together using two 4-40
x 3/8” (9.5mm) pan-head screws (Figure 6-5). Note: The upper left
and right corners of the control board may be touching the 2-D
fasteners, or there may be a small gap.
i
If the control board does not plug in easily, you may have one
or more connectors installed incorrectly.
The long-handled Allen wrench can be used to extract the control
board (Figure 6-4). To the left of J7 on the RF board you’ll find the
label “LIFT HERE” near a hole at the base of the control board. Insert
the Allen wrench into this hole, then rest the knee of the wrench on the
nearby screw head. Pry the board up with the wrench while guiding the
board out at the top.
Figure 6-5
Long-handled
allen wrench
Figure 6-4
Push the black keycap onto S1’s plunger until it snaps into place.
Test S1’s action (push on, push-off).
K2 Manual 1/24/99 V.XC ©1999 Elecraft
Alignment and Test, Part 1
In this section you’ll test most of the circuits on the control board and
front panel. Along the way you’ll become familiar with basic operation
of the K2, including use of the front panel switches, display, and menu.
Before proceeding with initial test, turn to the first page of the
Operation section of the manual to familiarize yourself with the K2’s
front panel layout. Do not turn on power to the K2 at this time.
43
For the remaining test and alignment steps, you’ll need a 12-14V
power supply or battery. A power supply rated at 300mA or more of
output current will suffice for the tests in Parts I and II, but higher
currents will be needed for transmitter tests in Part III. Always use a
well-regulated and filtered power supply or a battery.
If your power supply or battery does not already have a plug that
mates with the power jack (J3), use the supplied mating plug and
prepare a suitable power cable. The center lead of the plug is positive
(+).
The Tap/Hold Rule
Each of the push-button switches on the front panel has two functions,
one activated by a TAP (short press) and the other activated by a
HOLD (long press, about 1/2 second). The upper label on each switch
shows the TAP function (white lettering), and the lower label shows the
HOLD function (yellow lettering).
i
If you are presently using a 2.1mm DC barrel connector with
a low current rating (< 3A), we recommend that you replace it with the
supplied mating plug, which is a high-quality 5-amp unit.
Plug your power supply or battery into J3 on the rear panel.
Fold the tilt stand out to improve the viewing angle if desired.
Initial Test
i
i
If any test or alignment step fails, refer to the Troubleshooting
section.
Set the controls on the front panel as follows:
AF GAIN:
RF GAIN:
KEYER:
POWER:
OFFSET:
midway (12 o’clock)
maximum (clockwise)
midway
minimum (counter-clockwise)
midway
Perform the following resistance checks:
[resistance checks, TBD]
When you turn the K2 on for the first time, the nonvolatile
configuration memory (EEPROM) will be initialized. This process
takes approximately 10 seconds. During this period, the LCD backlight
will be OFF, and you will see I N F O 2 0 1 on the LCD. Displays
of this kind are referred to as “INFO” messages, and are used to alert
you to possible problems. In this case, the info message is just a
reminder that EEPROM has been initialized. (If you see any other
INFO messages, refer to Troubleshooting.) You
Turn on the K2 using S1. If you see or smell smoke, turn off
power and disconnect the power supply. See Troubleshooting.
After about 10 seconds, the LCD backlight should come on, and
the LCD should still be showing I N F O 2 0 1 as described above.
K2 Manual 1/24/99 V.XC ©1999 Elecraft
Tap any button on the front panel once quickly to clear the
I N F O message. You should then see the default K2 frequency
display for 40 meters: 7 1 0 0 . 0 0 c . The letter “c” indicates CW
mode. The annunciator for VFO A will also be turned on.
Turn the K2 off and wait for a few seconds, then turn it back on.
The display should now show E L E C R A F T on the LCD for
about two seconds, followed by the frequency display. Now that the
EEPROM is initialized, this is the display you should always see on
power-up.
44
Relay Test
Tap the DISPLAY button to return to the frequency display.
Tap the BAND+ button. You should see the band change to the
next higher band. At the same time, you’ll hear one or more relays.
(The relays are of the latching type and can easily be heard when they
are switched on or off.)
Tap the BAND button 7 more times to verify that you hear relays
being switched with each band change.
Move the “V SELECT” slide switch on the control board (S1) to
the “12V” position.
Note that the 160m (1.8 MHz) band does not appear in the list. It will
not be available unless the 160m/RXANT option is installed.
Tap the DISPLAY button once to select voltage/current display.
The display should now show something similar to this:
Tap the PRE/ATTN button three times. You should hear relays
switch each time.
E12.0 i0.06
This would indicate that the power supply voltage (E) is about 12.0V,
and the supply current (I) is about 60mA.6
Optical Encoder Test
Tap the DISPLAY button to return to the frequency display.
Turn the VFO knob in both directions and verify that the
frequency changes accordingly.
Tap the RATE button to the right of the knob to change the tuning
rate, and repeat the VFO test at each rate.
6
The supply voltage reading will reflect a small drop across D10, the
reverse-polarity protection diode, typically 0.2V on receive and 0.3V on
transmit. Accuracy of both current and voltage readings is about +/- 5%.
Voltmeter Probe Assembly (Optional)
If you do not have a DMM (digital multimeter), you can use the simple
DC voltage probe shown below in conjunction with the built-in
voltmeter. The crimp pin and 2-pin housing will be with the
MISCELLANEOUS components, in a smaller bag labeled PROBES.
Assemble the voltage probe as shown in Figure 6-1 using
stranded, 24AWG hookup wire. No ground connection is needed since
you will be measuring voltages inside the K2.
K2 Manual 1/24/99 V.XC ©1999 Elecraft
45
Hookup wire,
12” (0.3m)
Tap the MENU button on the K2. The first menu entry will be
displayed:
ST L 040
Tinned lead,
0.5” (13mm)
Crimp pin
Housing
Figure 6-1
Plug the voltage probe assembly into P5 on the control board. The
probe should be oriented so that the hookup wire is connected to the (+)
side of P5.
Move the V SELECT slide switch on the control board towards
P5. Select voltage/current display mode using the DISPLAY switch.
The voltage reading on the LCD should go to 0 0 . 0 .
To test the voltage probe, touch the tinned end of the hookup wire
to pin 1 of the I/O controller, U1 (RF board). The voltage displayed on
the LCD should be approximately 6V.
Return the V SELECT slide switch on the control board to the
“12V” position.
Note: Always disconnect the voltage probe when it is not in use. You
should not leave it connected inside the K2 during normal operation,
since it may cause shorts or unwanted noise pickup.
Menu Tutorial
We’ll present a brief tutorial on using the menu here, since you’ll be
using the K2 calibration features for some alignment steps. You’ll find
complete menu details in the Operation section, including a list of all
menu functions.
This is the sidetone level menu entry. 0 4 0 is the associated
parameter, in this case the sidetone volume setting. The row of
annunciators under S T L serves as an underline, reminding you
that turning the VFO knob will change the menu entries.
Tap the MENU button again and you’ll return to the frequency or
voltage/current display, depending on what display mode was selected
when you entered the menu.
Tap MENU again to bring up the menu. Turn the VFO knob now, and
you’ll see the other menu entries and their parameters scroll by. (You
can also tap the BAND+ or BAND- buttons to scroll through menu
entries.) Scroll the menu until you see
INP HAND
This menu entry is used to select the keying device. H A N D means
that the key jack is configured for a manual handkey or external keyer.
Press and hold the MENU button for 1/2 second to activate the EDIT
function. (Remember the TAP/HOLD rule: when you HOLD a button
in, you activate the function indicated by the lower label on the switch.)
The display should now show:
INP HAND
Notice that the underline has moved to the parameter (H A N D ). This
tells you that you’re in EDIT mode, and that turning the VFO knob will
now change the parameter for the current menu entry.
K2 Manual 1/24/99 V.XC ©1999 Elecraft
Turn the VFO knob now to see the various keying input selections.
P D L n and P D L r configure the key jack for a keyer paddle, wired
for either normal (tip = dot) or reverse (tip = dash) operation.
Tap the MENU button again to exit EDIT mode. The underline should
return to the menu entry.
46
K2 Manual 1/24/99 V.XC ©1999 Elecraft
Using the Calibration Functions
Scroll the menu until you see
C A L O F F . This is the entry
point into the calibration sub-menu, which you’ll be using during
alignment.
Enter EDIT mode as you did above, moving the underline to the OFF
parameter. Then turn the VFO knob to see the various C A L
functions, including F C T R (frequency counter), F I L (crystal
filter configuration), P L L (VFO calibration), B I A S (driver
bias) and S H I / S L O (S-meter calibration).
If you select a C A L function, holding EDIT again activates the
function. That particular C A L function remains active until you tap
MENU again, which returns you to the menu. Another tap of MENU
returns you to the normal K2 display.
In the following section you’ll activate the C A L F C T R
(frequency counter) function. For now, just tap MENU once or twice to
return to the normal display.
Frequency Counter Probe Assembly (Required)
Cut an 8” (20cm) length of RG-174 cable and carefully remove
1/2” (13mm) of the coax jacket from each end.
Separate the braid from the center conductor at both ends. Remove
1/4” (6mm) of insulation from each center conductor. At one end, cut
the braid off completely right at the coax jacket (a ground connection
will not be needed for frequency measurements). The braid should be
twisted into a fine bundle at the other end.
47
In the bag labeled MISCELLANEOUS you’ll find the
components for the frequency counter probe (Figure 6-1). These
components include a 10pF capacitor, two crimp pins, a 2-pin housing,
and a 1-pin male connector (probe tip).
Solder crimp pins onto the center conductor and shield at the
housing end of the cable. At the other end, solder a 10pF disc capacitor
to the center conductor using short leads (1/4”, 6mm).
Probe
tip
10pF
RG-174 Coax,
8” (20cm)
Housing
Heat-shrink tubing
Figure 6-1
Use a one-pin male connector as a probe tip. (This is an
appropriate probe tip, since it will be inserted into various female test
points on the RF board.) Solder the 1-pin connector to the capacitor as
shown.
Slip a 1.5” (4cm) length of heatshrink tubing onto the probe tip
components and shrink the tubing using a heat gun. (If you do not have
a heat gun, use a match or butane lighter.)
K2 Manual 1/24/99 V.XC ©1999 Elecraft
Plug the frequency counter probe assembly into P6, which is at the
far left end of the control board (as viewed from the front of the
transceiver). The shield wire of the coax cable should be aligned with
the ground symbol on P6.
Turn on the K2 and tap MENU to bring up the menu, then scroll
to the C A L menu entry. Hold EDIT, then scroll the C A L parameter
until the display shows C A L F C T R .
48
Notice that turning the AF GAIN control does not affect the
sidetone volume. The sidetone is injected into the AF amplifier after the
volume control, so AF GAIN affects only the receiver volume.
Tap MENU to turn off the sidetone, then scroll up to the sidetone
pitch menu entry (ST P) using the VFO knob or by tapping the
BAND+ button. The display will show
ST P 0.60
Now hold EDIT again to activate the frequency counter function of the
C A L sub-menu. The LCD should show 0 0 0 0 . 0 0 .
Plug the frequency counter probe into P6 on the control board.
The frequency counter circuitry is sensitive, so it may pick up a stray
signal and show it on the display.
To test the counter, you can read the frequency of the 4 MHz
oscillator on the control board. Touch the counter probe tip to the left
side of trimmer capacitor C22, which is just below the 16C77
microprocessor. The LCD should now read very close to
4 0 0 0 . 0 0 .7
Remove the frequency counter probe.
Audio Amplifier and Tone Generator Test
Plug in a pair of low-impedance (4 to 32 ohm) headphones, stereo
or mono.
Enter the MENU and scroll to the sidetone level menu entry (S T
L ). Hold EDIT to activate the sidetone. You should now hear a clean
600-Hz audio tone. Turning the VFO knob should vary the volume.
7
This is not a valid indication of the actual microprocessor clock frequency,
since this oscillator is used as the reference for the frequency counter. For
details on calibrating the frequency counter, refer to the Operation section
under Advanced Operating Features.
This indicates that the sidetone pitch is set for 0 . 6 0 kHz (600 Hz).
Hold EDIT to turn on the sidetone, then vary the VFO knob. The pitch
of the sidetone should change to match the display.
Keyer
In the following steps you’ll test the keyer (audio tone generation only).
This tests the keyer jack, speed control, and potentiometer read circuits,
including the A-to-D converter on the microcontroller.
Plug a keyer paddle into the key jack. The plug must be stereo (2
circuit). (A mating stereo plug for the keyer jack is supplied with the
kit.)
Using the menu’s I N P entry, set up the keyer input for either
P D L n or P D L r as described previously.
Adjust the KEYER control. As soon as you turn it, the display
should show the keying speed (approx. 9-40WPM).
While listening with headphones, test the keyer paddle to verify
that both dot and dash are working.
K2 Manual 1/24/99 V.XC ©1999 Elecraft
S-Meter Alignment
The bargraph S-meter zero and sensitivity will be coarsely set in the
following steps. This process tests most of the AGC circuitry on the
control board, as well as the LED bargraph and its drive circuits. Smeter settings can be fine-tuned in Part II of the RF board alignment
using on-the-air signals.
Using the menu, select the C A L S L O function (S-meter
zero). Activate it by holding EDIT a second time as described
previously.
Turn the VFO knob until you see only the left-most segment of the
LED bargraph lit. Then turn the knob a bit more clockwise until this
LED just turns off.
Exit the C A L S L O function, then select
C A L S H I (S-meter full-scale sensitivity).
Turn the RF GAIN control fully counter-clockwise (minimum
gain). Adjust the VFO knob until you see segment 9 of the bar graph lit,
then turn it a bit more counter-clockwise until segment 10 just turns on
(right-most segment).
Turn the RF gain control back to its full clockwise position. The
bargraph LEDs should all be off when you get to maximum gain.
Exit the C A L S H I function.
Bargraph Current Test
In the following steps, you’ll test the current measurement circuit by
using the bargraph LEDs to establish a known current drain. This also
tests the bargraph LED brightness control circuit.
Enter the menu and verify that G R P H (LED bargraph mode)
is set for D O T , not B A R or O F F .
49
Set the RF gain control for minimum gain. Segment 10 of the
LED bargraph should now be on if you have done the S-meter
adjustment as described above.
Using the menu, select the L C D menu entry. Change the
parameter from N I T E to D A Y . At this point you’ll see the
L C D backlight turn off, and segment 10 of the LED bargraph will
get much brighter.
Exit the menu and tap DISPLAY to switch to voltage/current
mode. Write down the current reading.
Use the menu to change the G R P H mode to B A R . All 10
segments of the LED should now be on.
Exit the menu and check the current. It should now be about
150mA higher.
Use the menu to change G R P H back to D O T , and L C D
back to N I T E .
i
As you can see, the combination of L C D D A Y and
G R P H B A R can result in high peak current drain on receive.
When operating from a battery, D O T or O F F should be used to
conserve power. More information about conserving power is provided
in the Advanced Operating Features section.
K2 Manual 1/24/99 V.XC ©1999 Elecraft
50
Assembly, Part II
are listed in the order they appear on the RF board, starting with R9
(near the left edge, about halfway back).
In this section you’ll install the components for the synthesizer and
receiver circuits, the largest group of components in the kit. Most of the
components to be installed are on the front half of the board (see Figure
6-1).
Note: Remember to complete each line of resistors before proceeding to
the next line (i.e., install R9, then R16, then R10).
After all of the parts are installed, individual stages will be aligned and
tested. Detailed troubleshooting procedures are provided in the
Troubleshooting section should you need them.
In some steps a large number of components will be installed, then
soldered as a group. You should check for unsoldered pins after
completing each group, but you’ll also do a careful examination of the
entire board in the final steps to catch any pins that may have been
missed.
Unplug the control board. To avoid damaging any control board
components, use the long-handled Allen wrench as described in Part I.
Remove the bottom cover.
Remove the screws from the front panel assembly and unplug it
from the RF board. Pull it straight out from the bottom edge, near the
middle of the panel. This may be easier to do with the transceiver sitting
on its right side so that you can steady it with one hand and pull with
the other.
Remove the side panels by taking out the two screws along the
bottom edge of each panel.
__ R9, 100k (BRN-BLK-YEL) ⇒
__ R10, 1k (BRN-BLK-RED)
__ R32, 10k (BRN-BLK-ORG)
__ R30, 120 (BRN-RED-BRN)
__ R20, 270 (RED-VIO-BRN)
__ R25, 2.7k (RED-VIO-RED)
__ R15, 33 (ORG-ORG-BLK)
__ R13, 10k (BRN-BLK-ORG)
__ R17, 100k (BRN-BLK-YEL)
__ R5, 2.7k (RED-VIO-RED)
__ R16, 10k (BRN-BLK-ORG)
__ R31, 10k (BRN-BLK-ORG)
__ R33, 15k (BRN-GRN-ORG)
__ R28, 27k (RED-VIO-ORG)
__ R22, 3.3M (ORG-ORG-GRN)
__ R24, 2.7k (RED-VIO-RED)
__ R14, 10k (BRN-BLK-ORG)
__ R12, 560 (GRN-BLU-BRN)
__ R11, 560 (GRN-BLU-BRN)
__ R78, 22 (RED-RED-BLK)
__ R6, 100 (BRN-BLK-BRN)
__ R92, 33 (ORG-ORG-BLK)
__ R93, 820 (GRY-RED-BRN)
__ R72, 470 (YEL-VIO-BRN)
__ R96, 2.7k (RED-VIO-RED)
__ R73, 2.7k (RED-VIO-RED)
__ R7, 68 (BLU-GRY-BLK)
__ R91, 820 (GRY-RED-BRN)
__ R76, 10 (BRN-BLK-BLK)
__ R95, 2.7k (RED-VIO-RED)
__ R74, 47 (YEL-VIO-BLK)
__ R97, 33 (ORG-ORG-BLK)
__ R80, 680 (BLU-GRY-BRN)
__ R81, 1.8k (BRN-GRY-RED)
__ R82, 18 (BRN-GRY-BLK)
__ R101, 10k (BRN-BLK-ORG)
__ R107,100k (BRN-BLK-YEL) __ R111 5.6k (GRN-BLU-RED)
__ R112, 22 (RED-RED-BLK)
__ R90, 470 (YEL-VIO-BRN)
__ R89, 100 (BRN-BLK-BRN)
__ R88, 470 (YEL-VIO-BRN)
__ R84, 18 (BRN-GRY-BLK)
__ R85, 150 (BRN-GRN-BRN)
__ R83, 4.7 ohms (YEL-VIO-GLD)
Sort all of the remaining 1/4-watt resistors by value before
installing them in the next step. This will lessen the chance of an
assembly error and decrease time spent hunting for each value.
Install the resistor networks. Start with RP2, which is in the front
left-hand corner.
Install the following 1/4-watt resistors, orienting them so that the
first band is at the left or towards the bottom of the board. The resistors
__ RP2, 100K, 8 pins (8A3.104G)
__ RP3, 10K, 8 pins (8A3.103G)
__ RP6, 100K, 8 pins (8A3.104G)
__ RP4, 100K, 6 pins (6A3.104G)
K2 Manual 1/24/99 V.XC ©1999 Elecraft
__ RP5, 100K, 6 pins (6A3.104G)
51
K2 Manual 1/24/99 V.XC ©1999 Elecraft
52
Install the following diodes, starting with D18 in the front-left
corner. Be sure to orient the diodes according to their PC board
outlines.
Install the TO-92 package transistors listed below. Start with Q17,
near the middle-left edge.
__ D18, 1N4148
__ D7, 1N4007
__ Q17, 2N7000
__ Q19, J310
__ D11, 1N4148
__ D13, 1N4148
__ D6, 1N4007
The varactor diodes have a small plastic package, like a TO-92
transistor, but with two leads. Sort the varactor diodes into two groups:
type MVAM108 and type MV209. This will help avoid mixing them up
during assembly, since they look identical. The K2 will not function
correctly if these diodes are interchanged.
Install the MVAM108 diodes listed below. Orient the diodes so
that the flat side of each diode matches the flat side of its PC board
outline. They should be seated approximately 1/8" (3mm) above the
board.
Note: D17, D21 and D22 are in the front-left corner. D37 and D38 are
near the SSB option connector (J11). D29 through D34 are on the right
side near the crystal filter.
__ D17
__ D21
__ D37
__ D38
__ D29
__ D32
__ D30
__ D33
__ D22
__ D31
__ D34
__ Q16, PN2222A
__ Q20, 2N7000
__ Q18, J310
__ Q24, J310
i
In the following steps you'll be installing two metal-can
transistors (TO-39 package). Due to a PC board fabrication error, we
have supplied thin plastic spacers for each transistor. The spacers will
no longer be necessary with the next board revision. You’ll find the
spacers in the MISCELLANEOUS items.
Place plastic transistor spacers on the leads of Q21 and Q22
(2N5109).
Install Q21, which is located near U1 in the middle of the board.
Bend the leads on the bottom to hold Q21 in place, then solder.
Install Q22, which is to the right of the "ELECRAFT" label. Make
sure Q22 is flat against the board before soldering.
Carefully press a 3/4” (19mm) diameter by 0.25” (6.4mm) tall star
heat sink onto Q22. The heatsink should be pressed all the way down as
far as it will go, and should be positioned so that it doesn’t touch the
components around the transistor. You may need to spread the heatsink
apart slightly using a screwdriver as you guide it on.
Install Q12 (2N7000), which is to the right of Q22.
Install the MV209 diodes listed below. D16 and D23-D26 are in
the front-left corner. D39 is to the right of J7 (control board).
__ D16
__ D25
__ D39
__ D23
__ D26
__ D24
Sort all of the remaining capacitors by value to reduce the
possibility of assembly errors in the next step. If you are unsure of any
capacitor’s value and do not have a capacitance meter, the pictures in
the parts list (Appendix A) may help.
K2 Manual 1/24/99 V.XC ©1999 Elecraft
53
Install C167 (.001µF), which is near J11, the connector for the
SSB adapter. The leads on this capacitor should be formed to match its
PC board outline.
Install the following capacitors, starting with C86 in the front-left
corner. Since you’ve become familiar with capacitor labeling, only the
values are listed here. As before, integer values are in pF and fractional
values are in µF. Bend and trim each capacitor’s leads as it is installed.
__ C86, 0.1
__ C100, .001
__ C70, 5pF
__ C73, 47
⇒
__ C84, 120
__ C95, .01
__ C71, 82
__ C74, 20
⇒
__ C85, 120
__ C96, 1µF (105)
__ C72, 270ƒ
__ C82, .001
__ C79, .001
__ C55, .01
__ C65, 0.1
__ C80, .001
__ C59, 0.1
__ C61, .01
__ C54, .01
__ C81, .001
__ C38, .001
__ C58, .01
__ C68, 5pF
__ C76, 10pF
__ C63, .01
__ C89, .001
__ C62, .01
__ C156, .047
__ C52, .01
__ C146, .01
__ C153, 39
__ C64, .001
__ C92, .022
__ C87, .01
__ C154, 270
__ C158, .01
__ C141, .01
__ C151, 0.1
__ C155, .01
__ C67, 0.1
__ C94, 0.047
__ C175, .01
__ C144, 100
__ C53, .01
__ C57, .001
__ C145, .01
__ C172, .01
__ C177, .022
__ C178, 0.1
__ C169, 390
__ C159, .01
__ C163, .01
__ C170, .047
__ C166, .047
__ C184, .01
__ C174, 82
__ C176, 0.1
__ C168, .01
__ C143, .01
__ C162, .047
__ C173, 220
__ C165, .01
__ C160, .01
__ C142, .01
__ C164, .01
__ C180, 22
__ C185, 0.1
__ C182, 180
__ C181, .01
Install the following ICs, aligning the notched end of each IC with
the notch on its component outline. U6 is at the front-left.
__ U6, LMC662
__ U3, LT1252
__ U11, NE602
__ U5, LTC1451
__ U10, NE602
__ U12, MC1350
__ U4, MC145170
__ U9, LT1252
Install U8 (LM78L05), which has a plastic TO-92 package like a
transistor. U8 is located near the front left corner of the board.
Option-bypass jumpers W5, W2 and W3 are located on the right
side of the board, near the crystal filter. Use a short length of bare
hookup wire for each jumper. These jumpers should be formed so that
they lie flat on the board, and should not touch any adjacent
components.
Test points TP1, TP2, and TP3 are single-pin female connectors.
You may find it easiest to turn the board up on edge before installing
them so they’ll stay in place while soldering. TP1 and TP3 are in the
synthesizer area of the board. TP2 is near the SSB option connector,
J11.
Install the following RF chokes, with the first color band to the left.
RFC13 is near the middle of the board; RFC16 is near the front.
__ RFC13 and __ RFC16, 100µH (BRN-BLK-BRN)
Install the receive mixer, Z6 (TUF-1), below the “ELECRAFT”
label at the middle of the board. Make sure that Z6 is lined up with its
component outline and is flush with the board before soldering.
Install the electrolytic capacitors in the order listed below, starting
with C60 near the far left-hand edge. Insert the (+) lead of each
capacitor into the hole with the (+) symbol.
__ C60, 100µF
__ C93, 10µF
__ C103, 220µF
K2 Manual 1/24/99 V.XC ©1999 Elecraft
54
K2 Manual 1/24/99 V.XC ©1999 Elecraft
There are two sets of pre-matched crystals used on the RF board:
12.096 MHz (quantity 2) and 4.915 MHz (quantity 9). Sort the crystals
into two groups.
Slip a thin, plastic crystal spacer onto the leads of each crystal.
Install the two 12.096 MHz crystals, X1 and X2, at the lower left.
The crystals should be seated flat on the board before soldering (it is
OK to bend the pins to hold them to the board).
To the left of X1 and X2 you’ll find pads for grounding the crystal
cases. Use short lengths of bare wire to ground the crystals on at the top
of the can as you did with the crystals on the control board. You may
wish to make use of clipped component leads.
55
Locate a 3/8” (9.5mm) diameter ferrite toroidal core (type FT3743). Ferrite cores can be identified by their dull appearance; ceramic
(powdered iron) cores are more polished. Be careful not to confuse this
type of core with the other black cores in the kit, which are either much
larger or have a polished finish.
Find RFC14’s component outline on the RF board, near the front
left-hand corner. Compare this component outline to Figure 6-1, which
shows two views of a typical single-layer toroidal inductor. RFC14
will be mounted vertically as shown at the right side of the drawing,
with one wire exiting at the core’s upper left, and the other at the lower
right. There are pads on the PC board in these two locations.
Install 4.915 MHz crystals at X3 through X11. X3 and X4 are
near the front-middle of the board, and the others are to the right of
these.
Ground the cases of X3-X11 in the same manner as X1 and X2.
Sort the slug-tuned shielded inductors into two groups: 1µH
(“T1050”) and 4.7µH (“T1005”). You should have four 1µH and eight
4.7µH inductors.
Install 4.7µH slug-tuned inductors at L30 and L34. Make sure
that the inductors are labeled “T1005.” Press these inductors down as
far as they’ll go, and verify that they’re seated flat against the board
before soldering.
i
In the following steps you’ll install several toroidal inductors,
which like other inductors can have “L,” “RFC,” or “T” reference
designators. They are not difficult to wind, but they must be wound as
indicated in the instructions or the transceiver will not operate correctly.
(The number of turns shown in illustrations will not be the actual
number of turns required in some cases, so count your turns carefully.
Turns counting is explained below.)
Remove insulation
Figure 6-1
To wind RFC14, cut a 9” (23cm) length of #24 red enamel-coated
wire, then “sew” the long end of the wire through the core exactly 10
times. Each pass through the core counts as one turn. When you’re
finished, the winding should look very similar to Figure 6-1.
Note: All toroids will be wound with #24 red enamel wire unless
otherwise noted.
K2 Manual 1/24/99 V.XC ©1999 Elecraft
Verify that the turns of RFC14 are not bunched together. They
should occupy about 85% of the core’s circumference. If the turns are
bunched together, RFC14’s inductance value will not be correct.
(Unless otherwise specified, 85% of the core should always be used.)
Stripping Toroid Leads
The best stripping method is to dip the leads into a solder pot, which
removes the insulation and tins the leads at the same time. However, the
most commonly-used method is to burn the insulation off by heating it
with a match or small butane lighter for a few seconds, then use finegrain sandpaper to remove the enamel residue. Avoid scraping
insulation off with a razor blade, as this may nick the wire.
Strip and tin the leads of the toroid before you mount it on the
board. (See above for stripping techniques.) As shown in Figure 6-1,
you should remove the enamel from the leads up to about 1/8” (3mm)
from the core.
Install RFC14 vertically as shown by its component outline, near
the front left-hand corner of the board, then pull the leads taut on the
bottom of the board.
Solder the leads of RFC14. When soldering, make sure that the
solder binds well to the leads. If the lead appears to be an “island” in a
small pool of solder, chances are it is not making good contact. It’s a
good idea to measure from pad to pad using an ohmmeter to be sure the
leads are making contact.
i
T5 is a toroidal transformer, with two windings. When
describing transformers, we’ll always refer to these windings using
pairs of numbers. These numbers are printed next to each pad on the
PC board, and they also appear on the schematic drawing (Appendix
B). T5’s windings are 1–2 and 3–4.
56
T5 will be wound on a yellow powdered-iron core (T50-6, 1/2”
[12.7mm] diameter). Wind the first winding, 1-2, using 16 turns of #24
red enamel wire (15”, 38cm). This winding must occupy 85% of the
core, and will look very similar to Figure 6-1. Remember that each pass
through the core counts as one turn.
Carefully strip and tin the leads of T5’s 1-2 winding.
T5’s other winding, 3–4, uses 4 turns of #24 green enamel wire
(7”, 18cm). Wind the 3–4 winding on top of the 1–2 winding,
interleaving the turns as shown in Figure 6-1. Strip and tin the leads of
the 3–4 winding.
Field Test Technical Note: T5’s 3–4 winding must be wound out of
phase (as illustrated) to accommodate an error in the PCB layout. It
will be corrected with a PC layout change in the next revision of the kit.
3
1
Green,
4 turns
2
4
Figure 6-1
K2 Manual 1/24/99 V.XC ©1999 Elecraft
57
Install T5 as shown by its component outline in the synthesizer
area of the board. Figure 6-2 shows how the 1–2 and 3–4 windings are
oriented with the numbered pads. Pull T5’s leads taut on the bottom of
the board, but do not solder yet.
2
1
Secure T5 to the board as shown in Figure 6-2 using a 3/8”
(9.5mm) diameter nylon washer, 1/2” (12.7mm) long nylon 4-40 screw,
and a #4 nylon nut. Tighten the nylon nut just enough to hold the
assembly in place. Do not over-tighten as this will strip the threads.
Solder T5, checking for good solder joints as before.
3
4
3
Figure 6-3
1
Install T7 as shown by its component outline near the front-right
corner of the board, with the windings oriented as shown in Figure 6-3.
Pull the leads taut on the bottom and solder.
2
4
Figure 6-2
T7 is a toroidal transformer wound on a 3/8” (9.5mm) diameter
ferrite core (black, FT37-43). T7’s orientation and windings are shown
in Figure 6-3. Wind T7’s 3–4 winding first, using 11 turns of red
enamel wire (12”, 30cm). Next, wind the 1–2 winding using 3 turns of
green enamel wire (5”, 13cm). Strip and tin the leads of both windings.
K2 Manual 1/24/99 V.XC ©1999 Elecraft
58
i
T6 is the only toroidal inductor in the kit that is wound with
#28 wire; all others use #24.
Transformer T6 is mounted vertically, near the middle of the
board. It uses a different winding technique where the wires for the two
windings are twisted together before winding. Locate the two lengths of
#28 enamel wire, one red and one green. Twist them together over their
entire length. The wires should cross over each other about once every
1/2” or 1cm.
Wind the twisted wires onto a 3/8” (9.5mm) ferrite core (FT3743), using exactly 10 turns. Use the same method you used when
winding non-twisted wires, covering about 85% of the core. Figure 6-4
shows how the winding should look (your turns count will be 10 rather
than 8 as in the drawing).
2
(GRN)
1
(RED)
4
(GRN)
3
(RED)
Figure 6-4
When winding is completed, clip and untwist the ends of the
red/green pairs so that the leads of the transformer looks like those in
Figure 6-4. The pin numbers shown match the component outline, with
the red wires numbered 1-3 and the green wires numbered 2-4.
Strip and tin all four wires. Be very careful not to strip the leads
so close to the core that the red/green wire pairs might short together.
Install T6 vertically, with the numbered wires inserted as indicated
in Figure 6-4. Pull the leads taut on the bottom, then solder.
Install the components listed below, starting with C4 in the back
left corner (near the key jack). Orient the components as you have in
previous steps.
K2 Manual 1/24/99 V.XC ©1999 Elecraft
__ C39, .001
__ C5, 100
__ C6, 5pF
__ C4, 820
__ C9, .001
__ C7, 100
__ C8, 820
__ W6 (option bypass jumper)
__ R38, 1k (BRN-BLK-RED)
__ C108, .01
__ D1, 1N4007
__ D2, 1N4007
__ RFC1, 100µH (BRN-BLK-BRN)
__ C107, .01
__ C110, .01
__ D5, 1N4007
__ R37, 100k (BRN-BLK-YEL)
__ C109, .01
__ D3, 1N4007
__ D4, 1N4007
__ R39, 1k (BRN-BLK-RED)
__ Q2, ZVN4424A
__ C114, .01
__ C113, .01
__ W1 (option bypass jumper)
59
K2 Manual 1/24/99 V.XC ©1999 Elecraft
60
RFC3 is wound on an FT37-43 core (black) using 16 turns of #24
red enamel wire (12”, 30cm). Wind this inductor in the same manner as
RFC14. Install RFC3 vertically as shown on the board, just to the left
of jumper W1.
Install 4.7µH slug-tuned shielded inductors at L1 and L2, near the
back-left edge of the board.
Install the 40-meter low-pass filter components, which are listed
below. These components are located just above Q22 (2N5109
transistor with heatsink). L25 and L26 are wound on T44-2 cores (red)
using 16 turns of #24 red enamel (15”, 38cm).
__ C225, 470
__ C227, 470
__ L25
__ L26
__ C226, 820
Flip the RF board over with the front edge still facing you. Install
the following components on the bottom side of the board, starting with
C207 at the back left. Once all components have been installed, solder
them on the top side, being careful not to damage any adjacent topmounted components.
front panel connector (P1). It must be seated flat against the bottom of
the PC board to prevent mechanical instability. Hold it firmly against
the board on the bottom while bending its leads on the top side, then
trim the leads and solder on the top of the board.
Install shielded solenoidal inductor L31 (12µH) in the same
manner as L33. It is located on the bottom of the board to the right of
L33. When soldering L31, be careful not to damage diode D18, which
is on the top side of the board near one of L31’s leads.
Install the final group of components listed below on the bottom of
the board. The list is in approximately left-to-right order within groups,
starting with C183, which is near the front left corner.
__ C183, .01
__ C150, 330
__ C161, .01
__ C90, .047
__ C157, .047
__ R79, 1.8k (BRN-GRY-RED)
__ R75, 680 (BLU-GRY-BRN)
__ R94, 82 (GRY-RED-BLK)
__ R100, 820 (GRY-RED-BRN)
__ R77, 220 (RED-RED-BRN)
__ R99, 470 (YEL-VIO-BRN)
__ R98, 120 (BRN-RED-BRN)
__ RFC11
100µH (BRN-BLK-BRN)
and __ RFC12,
__ D36, 1N4007
__ C207, .001
__ C204, .001
__ C133, .01
__ C119, .01
__ C104, 68pF
__ C216, .001
__ C208, .001
__ C135, 0.1
__ C17, .001
__ R34, 2.7k (RED-VIO-RED)
__ C223, .001
__ C195, .001
__ C122, 56
__ C27, .001
Note: Check the color bands on the following RF choke carefully. This is a
10 millihenry choke, not 10 microhenries.
__ RFC10, 10mH (BRN-BLK-ORG)
__ R65, 10k (BRN-BLK-ORG)
__ RFC2, 100µH (BRN-BLK-BRN)
__ RFC7, 15µH (BRN-GRN-BLK)
Locate L33, a 39µH shielded solenoidal inductor (black case, not
color coded). L33 is mounted on the bottom of the PC board near the
K2 Manual 1/24/99 V.XC ©1999 Elecraft
61
The component outline and one pad for resistor R8 (100 ohms,
BRN-BLK-BRN) were left off the revision XC PC board. To find the
correct location for R8, first find K16 and R76, just below U1 (near the
middle of the board). Next, turn the board over and find K16’s pads on
the bottom as shown in Figure 6-5.
Install R8 between the two pads shown in the drawing. The upper
pad is unused, but the lower pad is occupied by one lead of R7. Bend
R8’s lower lead so that it just touches this pad, then solder.
Visual Inspection
Examine the bottom (solder side) of the RF board carefully for
unsoldered pins, solder bridges, or cold solder joints. Since this is a
large board, you should break the examination up into three parts:
__ perimeter of the board
__ front half
__ back half
Examine the top (component side) of the RF board for unsoldered
pins, solder bridges, or cold solder joints. This step is necessary
because some components are installed on the bottom of the board.
Make sure switch S1 on the RF board is in the “OFF” position.
(Plunger OUT is OFF.)
(K16)
Perform the following resistance checks to insure that there are no
shorts in critical areas of the receiver or synthesizer:
[resistance checks TBD]
R8
Install the two side panels and secure with four chassis screws.
(R7)
Plug in the front panel assembly. Secure the front panel with four
chassis screws.
Plug in the control board.
Figure 6-5
Secure the front panel and control boards together using two 4-40
x 3/8” (9.5mm) pan-head screws.
Install the bottom cover and secure it temporarily using at least
two chassis screws.
K2 Manual 1/24/99 V.XC ©1999 Elecraft
Alignment and Test, Part II
In this section you’ll test and align the synthesizer and receiver circuits.
Once this is completed you’ll be able to test the receiver using all modes
on 40 meters.
Connect your power supply or battery.
Turn on the K2. You should see E L E C R A F T on the LCD,
followed by the standard frequency display.
Perform the following voltage checks.
[voltage checks TBD]
PLL Reference Oscillator Test
Plug the frequency counter probe into P6 on the control board.
Connect the probe tip to the PLL reference oscillator test point,
TP3. (This test point is located very close to the left side of the control
board, near U4 on the RF board.)
Using the menu, select C A L F C T R , then hold EDIT a
second time to enable the frequency counter. The counter should show a
frequency of 12090 kHz +/- 20 kHz. If you see a reading of 0000 kHz
or one that is changing rapidly, you may not have the frequency counter
probe connected properly. If you see a stable frequency reading that is
nowhere near 12090 kHz, chances are you have a problem in the PLL
reference oscillator. In this case refer to Troubleshooting.
When you’re in frequency counter mode, the BAND+ and BANDbuttons can be used to check the range of the PLL reference oscillator.
First, tap BAND+ and write down the frequency reading (typically
about 12098 kHz). Then tap BAND- and write down this frequency
reading (about 12085 kHz).
62
Subtract the lower frequency reading from the higher reading. If
the result is less than 10 kHz or more than 20 kHz you may have a
problem in the PLL reference oscillator stage. Typically the range is
about 13 kHz.
VCO Test
Use BAND+ or BAND- to select the 80-meter band, and set the
VFO for a frequency of about 4000.10 kHz.
Connect the frequency counter probe to the VCO test point, TP1.
Activate the frequency counter using C A L F C T R as before.
You should now see a frequency counter reading in the 8 to 10
MHz range. It may or may not be stable at this time (i.e., the frequency
may be changing). If the reading is 0000 kHz or is changing rapidly,
you probably don’t have the counter cable connected to the VCO test
point. If the reading is fairly stable but not between 8 and 10 MHz,
there’s a good chance that you have a problem in the VCO circuit.
Refer to Troubleshooting.
Disconnect the frequency counter probe and completely remove it
from the transceiver for now.
Exit CAL FCTR mode and return to the frequency display by
tapping the MENU button.
VCO Alignment
In the following steps you’ll adjust the VCO inductor (L30) so that the
VCO control voltage is in the proper range.
Make sure the is frequency still set at about 4000.10 kHz.
Connect a DMM (digital multimeter) to the left end of resistor
R30 (near the center of the synthesizer area of the RF board). Use a
small alligator clip to insure a good connection. (You can also use the
K2 Manual 1/24/99 V.XC ©1999 Elecraft
built-in voltmeter measure the VCO control voltage. Refer to Voltmeter
Probe Assembly in Part I.)
i
It is possible to damage the slugs in slug-tuned inductors if you
use a metal tool or if you tune the slug too far in or out. The tuning tool
provided will not damage the slugs, and will prevent turning it in too
far. Use only this tool.
Using the wide end of the plastic tuning tool, adjust the slug in
inductor L30 until the voltage at R30 reads 7.0V. If the voltmeter
reading does not change at all as you tune L30 through its full range,
refer to Troubleshooting. If the voltage changes but you cannot get to
7.0V, you have probably wound the VCO inductor (T5) incorrectly or
have installed the wrong value at L30 or C72.
Set the VFO for approximately 3500 kHz.
Measure and write down the VCO control voltage at this
frequency in Table 1, below, using pencil.
For each remaining band, set the VFO to the low and frequencies
listed below and write down the VCO control voltages.8
Table 1. VCO Voltage Readings
Band
80m
40m
30m
20m
17m
15m
12m
10m
8
Low Freq.
3500
7000
10000
14000
18000
21000
24800
28000
Voltage
High Freq.
Voltage
______ 4000
7.0
______ 7300
______
______ 10200
______
______ 14400
______
______ 18200
______
______ 21500
______
______ 25000
______
______ 28800
______
Usable VFO coverage extends well beyond the ranges given in the table.
63
If the VCO control voltage readings are < 1.5V or > 7.5V on some
bands, you have probably installed the wrong value at one or more of
the VCO capacitors (C70-C76) or varactor diodes (D21-D26). If you
replace any of these components you’ll need to repeat the entire VCO
alignment process.
BFO Test
Connect the frequency counter to the BFO test point (TP2), which
is on the right side of the RF board near the crystal filter.
Using the menu, select C A L F C T R . The counter should
show a frequency of 4913 +/- 3 kHz. If you see a reading of 0000 kHz
or one that is changing rapidly, you may not have the frequency counter
probe connected properly. If you see a stable frequency reading that is
nowhere near 4913 kHz, you may have installed the wrong crystals in
the BFO (X3/X4).
When you’re in frequency counter mode, the BAND+ and BANDbuttons can be used to check the range of the BFO. First, tap BAND+
and write down the frequency reading below (typically about 4916
kHz). Then tap BAND- and write down this frequency reading (about
4911 kHz).
BFO High Freq.BFO Low Freq.
Range (kHz)
____________ ____________ __________
Subtract the lower frequency reading from the higher reading. If
the result is less than 3.5 kHz or more than 6.5 kHz you may have a
problem in the BFO. Typically the range is about 5 kHz.
K2 Manual 1/24/99 V.XC ©1999 Elecraft
BFO Alignment
The K2 uses a variable-bandwidth crystal filter, allowing the operator
to set up three filter bandwidths for each operating mode. Filter set up
is done with the C A L F I L menu function. You must run C A L
F I L as explained in the following steps to complete setup of the
factory defaults.
Note: More details can be found in Operation / Calibration Functions /
Filter Settings. This section lists all of the factory default filter and
BFO values.
Follow the procedure below to complete setup of the factory
default filter settings for CW-Normal mode.9
1. Select CW mode (using MODE) and FL1 (using XFIL).
2. Select C A L F I L in the menu; hold EDIT to confirm.
3. The display will now show F L 1 0 4 0 c , showing that CW
filter FL1 is set to 40.10
4. Tap the BAND(-) switch. The display will change to
BF1
1 5 9 c . This indicates that the BFO setting for CW filter FL1 is
159.
5. Change the BF1 value from 159 to 160 then back to 159.
6. Tap the XFIL button to move to the next filter. The built-in
frequency counter will first measure, display, and record the BFO
frequency for filter FL1 (roughly 4913kHz).
7. The display will now show B F 2 1 5 9 c , the BFO setting for
the second CW filter (FL2). Modify the setting by a small amount
as before, then tap XFIL again to record the change and move on to
the next filter.
8. The display will now show B F 3 1 5 9 c . Modify the setting as
before, then tap XFIL. This completes set up of the CW-Normal
filters.
9
A future version of the firmware will automate this procedure.
This is not a direct indication of the filter bandwidth. See Calibration
Functions/Filter Settings in the Operation section of the manual.
10
64
Using the same technique, set up the defaults for the other
operating modes (CW Reverse, LSB, USB, and RTTY):
9. Hold CW REV to change to CW Reverse. The display will show
B F 1 1 5 9 c but with a "bar" over the C. Perform steps 5-8.
(above) to accept the defaults for all three CW Reverse filters.
10. Tap MODE to change to LSB. The display should show F L 1
1 5 9 L . Repeat steps 5-8 to accept all of the LSB filter defaults.
11. Tap MODE to change to USB. The display should show F L 1
2 0 5 U . Repeat steps 5-8 for all USB filter defaults.
12. Tap MODE to change to RTTY. The display should show F L 1
1 5 0 R . Repeat steps 5-8 for all RTTY filter defaults.
Tap the MENU switch to exit CAL FIL and return to the
frequency display.
VFO Linearization
The following procedure is used to linearize VFO tuning. For best
results, you should perform this calibration step at room temperature
(approx. 20-25°C). The VFO will then tune correctly at both lower and
higher operating temperatures.
Connect the internal frequency counter cable to the VFO output
test point (TP1).
Use the procedure listed below to linearize the VFO on 40 meters.
If you see any INFO messages, refer to Troubleshooting.
1. Use BAND+ or BAND- to select 40 meters.
2. Set the VFO to 7100.10 kHz.
3. Enter the menu and select C A L P L L , then hold EDIT a
second time to start the VFO linearization sequence.
4. The frequency counter will show the VCO frequency as it decreases
through a 5 kHz range. The letter N will flash to indicate storage
of 51 calibration table entries.
K2 Manual 1/24/99 V.XC ©1999 Elecraft
5. When calibration is completed (about 2 minutes), you'll hear a
short alert tone and see the message E N D on the LCD. You can
then tap any button to return to normal operation.
65
K2 Manual 1/24/99 V.XC ©1999 Elecraft
I.F. Amplifier Alignment
Note: L34 is a slug-tuned inductor, located near the right front corner of
the RF board, very close to the Control board. The label for L34 is
difficult to see with the Control board plugged in.
Using the wide end of the plastic tuning tool, adjust the slug in
L34 until it is near the top of the can. Stop turning the slug when it
appears to be at the top or as soon as you feel any resistance.
Turn L34’s slug one full turn clockwise (back down into the can).
This setting will suffice in most cases. After receiver alignment is
completed you may wish to peak this adjustment using a weak CW
signal. A moderate filter bandwidth (500Hz) should be used.
40-Meter Band Pass Filter Alignment
Set the band to 40 meters using BAND+ or BAND-.
Make sure the RF GAIN control is fully clockwise (max. gain).
Tap PRE/ATTN until the PRE annunciator turns on.
66
Note: you have an efficient antenna (such as a full-size dipole, beam,
vertical, or long wire), you should be able to turn the preamp OFF
when using 40 meters.
This completes 40-meter receiver alignment. In Part III you’ll install the
remaining band-pass filters and align the transmitter and receiver on all
bands. You may wish become familiar with the K2’s receiver features
before proceeding with Part III (see Operation).
Assembly, Part III
In this final RF board assembly section you’ll install the transmitter
components, as well as the remaining band-pass and low-pass filters.
This will allow you to align and test the K2 on all bands.
Turn off the K2 and disconnect the power supply.
Unplug the control board. Use the long-handled Allen wrench as
described in Part I.
Remove the bottom cover.
Connect a pair of headphones (stereo or mono) to the front panel
jack, and turn the AF gain control to about midway.
Remove the screws from the front panel assembly and unplug it
from the RF board.
Connect an antenna or signal generator to the antenna jack on the
rear panel. If you use a signal generator, set it for approx. 7150 kHz at
an output level of about -100 dBm.
Remove the side panels by taking out the two screws along the
bottom edge of each panel.
Tune in a signal in the range of 7100-7200 kHz if possible. (If you
cannot find a signal, you can use atmospheric noise from the antenna to
peak the filter.)
Using the plastic tuning tool, adjust both L1 and L2 (back left
corner) for peak signal strength. (You may be able to use the bargraph
if the signal is strong enough.) If you do not hear any signals or noise,
see Troubleshooting.
K2 Manual 1/24/99 V.XC ©1999 Elecraft
67
Install the following 1/4-watt resistors, starting with R46 which is
just to the left of I/O controller U1.
__ R46, 270 (RED-VIO-BRN) ⇒
__ R59, 4.7k (YEL-VIO-RED)
__ R49, 120 (BRN-RED-BRN)
__ R41, 560 (GRN-BLU-BRN)
__ R45, 47 (YEL-VIO-BLK)
__ R61, 120 (BRN-RED-BRN)
__ R40, 470 (YEL-VIO-BRN)
__ R55, 33 (ORG-ORG-BLK)
__ R53, 4.7 ohms (YEL-VIO-GLD)
__ R56, 33 (ORG-ORG-BLK)
__ R54, 4.7 ohms (YEL-VIO-GLD)
__ R62, 2.7k (RED-VIO-RED)
__ R67, 1.5K, 1% (BRN-GRN-BLK-BRN)
__ R68, 237 ohms, 1% (RED-ORG-VIO-BLK)
__ R69, 100k (BRN-BLK-YEL)
⇒
__ R66, 2.7k (RED-VIO-RED)
__ C11, 1800
__ C15, 560
__ C19, 330
__ C25, 330
__ C36, 330
__ C31, 56
__ C48, 220
__ C115, .01
__ C116, 33
__ C131, 0.1
__ C130, 0.1
__ C127, 680
__ C197, 100
__ C211, 10
__ C138, .047
__ C220, 220
⇒
__ C212, 150
__ C200, 150
__ C192, 1200
__ C203, 47
__ C202, 120
i
There are two types of ceramic trimmer capacitors used in the
band-pass filters: 30pF and 50pF. Since the two are difficult to tell
apart, we have added a red mark on the body of the 50pF trimmers.
Install the trimmers listed below, starting with C21 near the backleft corner. Orient the flat side of each trimmer capacitor with the flat
side of its component outline. This orientation is required to prevent RF
pickup during alignment.
Install the capacitors listed below. C12 is near the back left
corner. Integer values are in pF; fractional values are in µF.
Note: C13 and C14 will not be installed; they are included with the
160m/Receive Antenna option.
__ C12, 560
__ C16, 1800
__ C20, 47
__ C24, 47
__ C37, .001
__ C49, .001
__ C43, 33
__ C45, 2pF
__ C118, .01
__ C120, 0.1
__ C124, 0.1
__ C129, .01
__ C190, 1200
__ C210, 82
__ C219, 12
__ C221, 39
__ C213, 33
__ C199, 220
__ C201, 220
__ C26, .001
__ C22, 3pF
__ C30, 330
__ C35, 56
__ C33, 3pF
__ C42, 220
__ C47, 33
__ C117, .047
__ C121, 0.01
__ C128, 680
__ C191, 1800
__ C198, 27
__ C218, 150
__ C222, 100
__ C214, 68
__ C21, 50pF (red mark)
__ C32, 30pF
__ C44, 30pF
__ C23, 50pF (red mark)
__ C34, 30pF
__ C46, 30pF
Set all of the trimmer capacitors just installed to their mid-way
point (see Figure 6-1). Use a small flat-blade screwdriver.
Figure 6-1
Install L5, a 33µH RF choke (ORG-ORG-BLK), near the backleft corner.
Install the following transistors, which are located just above the
I/O Controller (U1).
__ Q10, 2N7000
__ Q13, PN2222A
__ Q11, PN2222A
K2 Manual 1/24/99 V.XC ©1999 Elecraft
Ferrite-bead assemblies Z1 and Z2 will be installed vertically near
transformer T3 as indicated by their component outlines. To make these
assemblies, string two ferrite beads onto a 1” (25mm) length of hookup
wire as shown in Figure 6-2.
68
Flip the RF board over and install the following components on
the bottom, working from left to right.
__ R63, 220 (RED-RED-BRN)
Note: bend the leads of the following 1/2 watt resistor as shown by its
component outline.
__ R58, 180 ohms, 1/2 watt (BRN-GRY-BRN)
__ RFC8, __ RFC9, __ RFC4,
10µH (BRN-BLK-BLK)
__ RFC6, 0.68µH (BLU-GRY-SILVER)
__ RFC5, 10µH (BRN-BLK-BLK)
__ R50, 1.5 ohms (BRN-GRN-GLD)
Figure 6-2
Install Z1 and Z2, bending the leads on the bottom of the board to
hold them in place. Make sure that the beads are seated flat against the
PC board, then solder.
Install trimmer potentiometer R60 (100 ohms), which is near Q13.
Set the trimmer to its midpoint.
Locate D9, a 1N34A diode. This is a glass-packaged diode that is
somewhat fragile. Install D9 near the right edge of the board.
__ R48, 120 (BRN-RED-BRN)
__ R43, 22 (RED-RED-BLK)
__ R47, 47 (YEL-VIO-BLK)
__ R42, 4.7 ohms (YEL-VIO-GLD)
__ R44, 2.7k (RED-VIO-RED)
Make sure you have separated the remaining slug-tuned shielded
inductors into 1µH and 4.7 types. Install these inductors in the order
indicated below, on the top of the board. These inductors are difficult to
remove once soldered, so double-check the part numbers.
Install electrolytic capacitors C126 (47µF) and C137 (100µF),
both near R60. Insert the (+) lead of each capacitor into the hole with
the (+) symbol.
__ L3, 4.7µH
__ L8, 4.7µH
__ L4, 4.7µH
__ L9, 4.7µH
Install electrolytic capacitor C125 (22µF) which is near U1.
__ L10, 1µH
__ L12, 1µH
__ L11, 1µH
__ L13, 1µH
Place a thin plastic transistor insulator over the leads of Q5 before
installing it.
Install Q5 (2N5109). Be sure Q5 is firmly seated on the board and
has its tab oriented as shown by the component outline before soldering.
K2 Manual 1/24/99 V.XC ©1999 Elecraft
69
i
TO-220 package transistors Q6, 7, and 8 look identical, but
Q6 is different. Locate the two 2SC1969’s, Q7 and Q8, and set them to
one side. The 2SC2166 transistor, Q6, will be installed first.
Attach a self-adhesive thermal pad to the PC board on top of the
component outline for Q6. The hole in the thermal pad must be aligned
precisely with Q6's mounting hole on the board.
Prepare the leads of Q6 as you did with the voltage regulators on
the Control board, then insert Q6 as shown by its component outline.
Secure Q6 to the board using a 4-40 x 3/8” (9.5mm) screw, #4
lockwasher and 4-40 nut. The body of the transistor must not contact
the leads of any adjacent components.
i
It is very important to wind and install toroidal transformers
T1 through T4 exactly as described in the following steps. Remember
that transformer windings are identified by numbered pairs of leads,
which correspond to the PC board and schematic.
T1 is wound on an FT37-43 ferrite core (black) and has windings
similar to those shown in Figure 6-3. The 1–2 winding is 9 turns of red
enamel wire (10”, 25cm). The 3–4 winding is 3 turns of green enamel
wire (5”, 13cm).
Prepare T1’s leads as in Part II. Completely remove the insulation
to within about 1/8” (3mm) of the core, then tin the leads.
3
1
Solder Q6.
Wind and install each of the low-pass filter inductors listed below,
starting at the back-right with L16 and L17 (80 meters). Wind each of
the toroids using the core type and number of turns indicated (use red
#24 enamel wire). Review the toroid winding instructions and
illustrations for RFC14 (Part II) before proceeding.
Note: The black cores used below are all of the powdered-iron
(ceramic) type. If necessary you can identify them by measuring their
diameter, which is 0.44” (11mm).
__ L16
__ L17
__ L18
__ L19
__ L20
T44-2 (red), 21 turns
T44-2 (red), 21 turns
T44-2 (red), 9 turns
T44-2 (red), 8 turns
T44-2 (red), 7 turns
19” (48cm)
19” (48cm)
10” (25cm)
9” (23cm)
8” (18cm)
__ L21
__ L22
__ L23
__ L24
T44-10 (black), 9 turns
T44-10 (black), 8 turns
T44-10 (black), 11 turns
T44-10 (black), 10 turns
10” (25cm)
9” (23cm)
11” (28cm)
10” (25cm)
2
4
Figure 6-3
Install T1 horizontally near Q5, inserting the leads into the
matching numbered holes as indicated by the above illustration and by
the component outline.
K2 Manual 1/24/99 V.XC ©1999 Elecraft
70
T2 is wound on the same core type as T1, and its windings are
also similar to Figure 6-3. T2’s 1–2 winding is 12 turns of red enamel
wire (13”, 33cm), and its 3–4 winding is 8 turns of green (9”, 23cm).
A
(GRN)
Prepare T2’s leads as before.
Install T2 horizontally, just to the right of Q6.
Transformer T3 is mounted vertically, to the right of T2. The
wires for the two windings must be twisted together before winding.
First, cut two 14” (36cm) lengths of enamel wire, one red, and one
green. Then twist the wires together over their entire length. The wires
should cross over each other about once every 1/2” or 1cm.
C
(RED)
B
(GRN)
D
(RED)
Wind the twisted wires onto a 1/2” (12.7mm) ferrite core (FT5043), using exactly 10 turns and covering about 85% of the core. Figure
6-4 shows how the winding should look (except that you’ll have 10
turns, not 8). Note that the leads of T3 are labeled with letters A
through D to avoid confusing them with the numbered leads of T2 and
T4.
Separate T3’s leads as shown in Figure 6-4. Strip and tin the
leads, being careful not to let the red/green wire pairs short together.
Install T3 vertically as shown by its component outline. T3 must
be seated flat against the PC board, with its leads pulled tight on the
bottom side.
Figure 6-4
K2 Manual 1/24/99 V.XC ©1999 Elecraft
71
Locate the “binocular” (2-hole) ferrite core for T4. Wind 2 turns
of #22 Teflon-insulated hookup wire (5”, 13cm) through the core as
shown in Figure 6-5. This forms the 1–2 winding.
Cut and strip the two leads using the lengths shown.
Before installing T4, verify that the screws holding the 2-D
fastener beneath it are tightened, and that #4 internal-tooth lock washers
were used. It is important that these screws not come loose sometime
after T4 has been installed.
Install T4 to the right of T3, inserting leads for the 1–2 and 3–4
windings into their matching numbered holes. T4 should rest directly on
top of the screws that secure the 2-D fastener beneath it. T4 should also
be parallel to the board, not tilted to one side. Pull the leads taught on
the bottom and bend them to hold the transformer in place. Do not
solder T4 yet.
1
2
Use two 2” (5cm) lengths of bare hookup wire to form the 5–6 and
7–8 windings on T4 (Figure 6-7). Route the links through the core first,
then bend them down and insert them into their numbered holes and
solder. Do not solder the link windings yet.
1/2” (13mm)
7/8” (22mm)
Figure 6-5
5
6
8
7
Wind a 3-turn winding (3–4) on top of the 1-2 winding, but with
the wire starting and ending on the opposite side (Figure 6-6). Use 7”
(18cm) of #22 Teflon-insulated hookup wire.
3
Figure 6-7
4
Figure 6-6
Adjust the windings of T4 as needed so that the transformer is
positioned directly above its component outline. Pull the leads tight on
the bottom, then solder.
Inspect all four transformers in the transmitter area closely, on
both top and bottom, for shorts or cold solder joints.
K2 Manual 1/24/99 V.XC ©1999 Elecraft
i
Q7 and Q8 (2SC1969) must be installed on the bottom of the
PC board with their metal tabs facing the heatsink as explained in the
following steps. Locate the component outlines on the bottom of the
board before proceeding.
Prepare the leads of Q7 as shown in Figure 6-8. Bend the leads
upward, away from the tab--the opposite of the way you bent the leads
of Q6. Do not install Q7 yet.
72
Make sure the smaller part of the shoulder washer is pressed into
the hole in Q7’s metal tab (Figure 6-8).
Temporarily secure Q7 and its hardware with a 4-40 nut and #4
lockwasher.
Once Q7 and its hardware appears to be flat against the PC board
as shown in Figure 6-8, solder Q7 on the top of the board.
Repeat the steps above for the other PA transistor, Q8.
Uninstalled Components
At this point you should have several component locations that are not
filled. These locations are for parts that are provided with individual
option kits, which should not be installed until after the basic K2 kit is
completed and tested.
Figure 6-8
Check off the components in the list below, verifying that they are
not installed. The option module associated with each component is
indicated for reference.
Insert a 4-40 x 1/2” (12.7mm) screw through the PC board hole
for Q7’s tab (see Figure 6-8). Then slip the hardware listed below onto
this mounting screw from the bottom side. (Note: The shoulder washer
can be found with the MISCELLANEOUS components.)
Top side of the board, transmitter section:
__ 1/4” (6.4mm) dia., 0.15” (4mm) long self-retaining standoff (gray)
__ #4 nylon shoulder washer (Keystone #3049)
Top side of the board, receiver section:
Note: The self-retaining standoff provides a small amount of friction to
prevent the screw from sliding out during later assembly steps.
__ C75 (160m/RXANT)
__ J5 (low-level AF output)
__ J9 (SSB adapter)
__ P3 (Battery or PA)
Place Q7 on the bottom of the board so that the leads are inserted
into the PC board as indicated by Q7’s component outline. Do not
solder yet.
__ C13 (160m/RXANT)
__ J13 (Transverter I/O)
__ P6 (ATU or PA)
Bottom of the board:
__ R4 (160m/RXANT option)
__ C14 (160m/RXANT)
__ J14 (160m/RXANT)
__ J11 (SSB adapter)
__ J12 (Noise Blanker)
__ J10 (SSB adapter)
K2 Manual 1/24/99 V.XC ©1999 Elecraft
Install the two side panels and secure with four chassis screws as
you did in Part I and Part II.
Plug in the front panel assembly and make sure the connectors are
completely mated. Secure the front panel with four chassis screws.
73
Attach two self-adhesive thermal pads to the inside of the heat sink
as shown in Figure 6-1. The holes in the thermal pads must be aligned
precisely with the transistor mounting holes as shown.
Install the bottom cover and secure it temporarily using at least
two chassis screws.
Plug in the control board. Make sure that all three connectors are
completely mated.
Secure the front panel and control boards together using two 4-40
x 3/8” (9.5mm) pan-head screws.
Attach two round rubber feet to the heatsink using 4-40 x 3/8”
(9.5mm) screws, #4 lock washers, and 4-40 nuts. (The rubber feet can
be found with the MISCELLANEOUS items.)
Remove the finishing nuts and washers from the shafts of the
antenna and key jacks. They will be re-installed later.
Turn the K2 up on its right side panel, with the back of the
transceiver facing you.
Examine the bottom of the RF board in the transmitter area. Make
sure that no component has an installed height of over 1/4" (6.4mm).
Capacitors that protrude above this height must be bent downward at
i In the next
an angle to prevent them from hitting the heat sink.
step you'll install thermal insulation pads for the power amplifier
transistors, Q7 and Q8. These pads must be positioned on the heat sink
correctly to keep the collectors of the transistors from shorting to
ground. Proper positioning is also required to insure good heat
conduction.
Figure 6-1
Remove the 4-40 nuts and #4 lock washers from the mounting
screws for Q7 and Q8, but do not pull the screws out. (If you pull these
screws out, the associated hardware will fall off and will have to be reinstalled.)
Back out the mounting screws for Q7 and Q8 just enough so that
the heatsink can be fitted into position. The ends of the screws should
still protrude slightly from the transistor tabs.
Slip the heatsink over the rear-panel connectors first, then rotate it
into position on the bottom of the board. Once it’s in place, press the
Q7/Q8 mounting screws all the way back in so that they protrude from
the heatsink.
Between the Q7/Q8 mounting holes you’ll find two holes in the
heatsink; these provide access to the 2-D fastener between the
transistors. Use two chassis screws to hold the heatsink firmly in place
at this location. (The 2-D fastener provides a low-impedance ground
return path for Q7/Q8.)
Secure Q7 and Q8 on the bottom of the heatsink using 4-40 nuts
and #4 lock washers. Do not over-tighten the nuts.
K2 Manual 1/24/99 V.XC ©1999 Elecraft
Using an ohmmeter on a low resistance scale, check for a short
from Q7 or Q8 collector to ground. (This test should also be performed
any time the heat sink is removed and re-installed.) If a short is
measured, remove the heatsink and investigate the cause. The most
likely reason for a short is mis-alignment of a shoulder washer or
thermal pad.
There are four more #4 holes in the heatsink: two on the bottom
and two on the back panel. Use four chassis screws to secure the
heatsink to the side panels and RF board at these locations. You may
need to adjust the positions of the 2-D fasteners on the side panels.
Install the washers and finishing nuts that you removed earlier
from the antenna and key jacks.
74
Connect a 50 ohm dummy load to the antenna jack. The dummy
load should be rated at 5 watts or higher.
Connect a pair of headphones and a key or keyer paddle.
Set the POWER control to 0.0 watts.
Turn on the K2. You should see E L E C R A F T on the LCD,
followed by the frequency display.
Select voltage/current display mode by pressing DISPLAY to
make sure the receiver is not drawing excess current. (Typical current
drain will be 100-200mA depending on menu settings.)
Return to frequency display mode.
Switch to CW and select FL2 using XFIL.
Alignment and Test, Part III
In this section you’ll complete alignment and test of the K2 on all
bands.
Make sure the power switch, S1, is in the OFF position (out).
Perform the following resistance checks:
[resistance checks TBD]
Connect your power supply or battery. For transmitter tests, a
battery or well-regulated power supply that can handle at least 2 amps
is recommended. Avoid using a switching power supply unless it is well
shielded and includes EMI filtering. A linear supply will typically
generate much less noise.
Use the menu to set up the desired CW sidetone volume and pitch
if you have not already done so. Also set up the desired keying device
using I N P . If you’re using a hand key or external keyer, use I N P
H A N D . To use the internal keyer, select P D L n or P D L r
(normal or reverse paddle).
Use SPOT to verify that the sidetone is functioning. Tap any
button to turn the SPOT tone off.
K2 Manual 1/24/99 V.XC ©1999 Elecraft
40-Meter Transmitter Alignment
i
To align the transmitter you’ll need some means for monitoring
power output as you adjust the band-pass filters. An analog wattmeter
or oscilloscope is ideal. However, in the instructions that follow we’ll
assume that you’re using the K2’s built-in digital wattmeter, which will
also provide satisfactory results.
Set the POWER control for 3.0 watts.
Switch to the 40 meter band and set the VFO for mid-band (about
7150 kHz).
Locate the 40-meter band-pass filter inductors, L1 and L2, and be
prepared to adjust them using the wide end of the tuning tool.
i
You should limit key-down (TUNE) periods to about 5 or 10
seconds during tune-up for safety reasons. If you see or smell smoke
turn the K2 off immediately and refer to Troubleshooting.
75
If necessary, repeat the adjustment of L1 and L2 one or two times
to be sure that you have the inductors peaked correctly. If you cannot
get power output to 3.0 watts or higher, see Troubleshooting.
Make sure the bar graph is set for D O T mode using the
G R P H menu entry.
Set power output to 5.0W using the POWER control.
Tap DISPLAY to enter voltage/current display mode. When the
display is showing voltage and current, holding TUNE does not activate
the wattmeter. This allows you to check your voltage and current in
transmit mode.
Hold TUNE and note the change in voltage and current. Current
drain at 5 watts is typically 1 to 1.5 amps.12 If the current reading is
much higher than this, or if the voltage drops more than 1V, you may
have a problem in the transmitter (see Troubleshooting).
Return to frequency display using the DISPLAY switch.
Set the POWER control for 10.0 watts.
Note: While in TUNE mode, it is normal to see power increase a few
tenths of a watt. You may also see a sudden jump in power if power
output was 0.0 watts when you entered TUNE mode. If you see such a
jump in power output, tap any key to exit TUNE mode. The next time
you hold TUNE, power will be back to your original setting.11
Hold TUNE to put the K2 into transmit mode and activate the
built-in wattmeter. Using the tuning tool, adjust L1 for maximum
output. Tap any button to exit TUNE mode.
Hold TUNE just long enough to verify that the wattmeter reads
approximately 10 watts. If you then switch to voltage/current display
and hold TUNE again, you should see a current drain of typically 1.5 to
2 amps.
This completes transmitter alignment and test on 40 meters.
Hold TUNE again and adjust L2 for maximum output. Tap any
button to exit.
12
11
This type of power jump will be handled automatically in a future
firmware revision.
The K2 transmitter is most efficient at 10 watts. If you plan to operate
exclusively at 5 watts or less, see Modifications for ways to improve lowpower efficiency.
K2 Manual 1/24/99 V.XC ©1999 Elecraft
76
VFO Linearization (All Bands)
In Part II you completed the VFO linearization procedure on 40 meters.
In the following steps you’ll do the VFO linearization on the remaining
bands. This step must be completed before you can operate on any band
besides 40 meters.
Connect the frequency counter cable to the VCO test point (TP1).
i
Since some inductors are shared between two bands, you must
always align the remaining bands in the order indicated. Specifically, 30
meters must be aligned before 20 meters, 15 meters must be aligned
before 17 meters, and 10 meters must be aligned before 12 meters.
Switch to 30 meters (10100 kHz) and turn on the preamp. Adjust
L8 and L9 for maximum signal strength.
Switch to 80 meters. Set the VFO for 3700.10 MHz.
Perform steps 3-5 of the VFO Linearization procedure from Part
Switch to 20 meters (14100 kHz) and turn on the preamp. Adjust
C21 and C23 for maximum signal strength.
II.
Linearize the VFO on the remaining bands using the starting
frequencies listed below. Check off each band as it is completed.
__ 10000.10
__ 21200.10
__ 14200.10
__ 24900.10
__ 18100.10
__ 28300.10
Receiver Pre-Alignment (Optional)
Since the same filters are used on both receive and transmit, it is
possible to align all the remaining bands on transmit only. However,
you can pre-align the filters on receive by using either a signal
generator, separate ham transceiver, or antennas for each band. This
pre-alignment on receive will make transmitter alignment easier, since
the filter adjustments will already be at or close to their final values.
Switch to 80 meters and set the VFO for about 3750 kHz (midband). Turn on the RF preamp by tapping PRE/ATTN until you see the
PRE annunciator turn on.
Use a signal generator or an antenna to inject a signal or noise at
the this frequency.
Adjust L3 and L4 for maximum signal strength.
Switch to 15 meters (21100 kHz) and turn on the preamp. Adjust
L10 and L11 for maximum signal strength.
Switch to 17 meters (18100 kHz) and turn on the preamp. Adjust
C32 and C34 for maximum signal strength.
Switch to 10 meters (28200 kHz) and turn on the preamp. Adjust
L12 and L13 for maximum signal strength.
Switch to 12 meters (24900 kHz) and turn on the preamp. Adjust
C44 and C46 for maximum signal strength.
This completes receiver alignment.
Note: If you have efficient antennas on 80, 40 and 30 meters you
probably will not need the preamp turned on for these bands.
K2 Manual 1/24/99 V.XC ©1999 Elecraft
77
Transmitter Alignment
Note: If you did the receiver alignment, above, you may find that little
or no transmit adjustment is required on most bands. If you used a
signal generator to align the receiver, you probably won’t need to adjust
the filters on transmit at all.
Set the POWER control for 3.0 watts.
Switch to 80 meters and set the VFO for about 3750 kHz (midband).
Hold TUNE and adjust L3 and L4 for maximum power as
indicated on the internal wattmeter. (Use a more sensitive analog
instrument if available.) Limit TUNE time to 5 or 10 seconds.
i
The remaining bands should always be aligned in the order
listed below as explained in the Receiver Alignment instructions.
Switch to 30 meters (10100 kHz) and adjust L8 and L9 for
maximum power output.
Switch to 20 meters (14100 kHz) and adjust C21 and C23 for
maximum power output.
Switch to 15 meters (21100 kHz) and adjust L10 and L11 for
maximum power output.
Switch to 17 meters (18100 kHz) and adjust C32 and C34 for
maximum power output.
Switch to 10 meters (28200 kHz) and adjust L12 and L13 for
maximum power output.
Switch to 12 meters (24900 kHz) and adjust C44 and C46 for
maximum power output.
This completes transmitter alignment.
K2 Manual 1/24/99 V.XC ©1999 Elecraft
78
7. Final Assembly
Place the top cover upside down as shown in Figure 7-1, with the
rear panel facing backwards. The drawing shows how the speaker and
external speaker jack will be wired in the steps that follow.
As shown in Figure 7-1, there are two spare holes provided in the
top cover for the battery bracket. Use two 4-40 x 3/8” (9.5mm) screws
to fill the two holes, securing them with #4 lock washers and 4-40 nuts.
A 24” (60cm) length of two-conductor speaker cable is supplied
with the kit. Cut the speaker cable into two pieces, one 16” (40cm) long
and the other 8” (20cm) long.
Install the external speaker jack in the hole labeled “EXT SPKR”
on the rear panel.
Battery bracket
support screws
Solder crimp pins to the two the wires at one end of the 16”
(40cm) length of speaker cable (Figure 7-2). Insert the copper wire into
the pin 1 position of a two-pin housing as shown. Insert the other wire
into the pin 2 position.
Copper wire
8” (20cm)
Pin 1 side
16” (40cm)
Housing
Crimp pin
Figure 7-2
Figure 7-1
Attach the speaker to the top cover in the position shown using
four 3/8” (9.5mm) long 4-40 screws, #4 lock washers, and 4-40 nuts.
Connect the other end of this cable to the external speaker jack as
shown in Figure 7-3. The copper wire must be connected to the “AF”
lug of the speaker jack. Solder only the copper wire.
K2 Manual 1/24/99 V.XC ©1999 Elecraft
79
for clarity. They should be pulled tight to hold the two lengths of
speaker cable together. Trim any excess cable tie length.
Ground
SP
AF
Copper wire
Note: An extra .01µF bypass capacitor is provided with the
MISCELLANEOUS items that may be used if needed to suppress RF
pickup at your speaker terminals or at the EXT. SPKR jack. If you
hear loud clicks in the internal or external speaker when transmitting at
moderate to high power levels, you may need the bypass cap. [TBD]
Hole Covers
Figure 7-3
Connect one end of the 8” (20cm) speaker cable to the speaker
terminals. The copper wire should be connected to the lug marked (+).
Solder both wires.
Connect the other end of this cable to the external speaker jack as
shown in Figure 7-4. The copper wire must be connected to the lug
marked “SP.” Solder all three lugs.
Hole covers for the accessory connector holes in the top cover and heat
sink were not available in time for field test. These will be supplied free
of charge to field testers when they become available.
Finishing Touches
Examine the control board one last time to be sure that it is
correctly plugged into the RF board. All three connectors must be
mated completely.
If you have not completed alignment on all bands, you may wish
to do so at this time.
Ground
SP
Copper wire
Figure 7-4
Use cable ties at the points shown in Figure 7-1 to hold the
speaker wiring in place. The drawing shows the cable ties un-cinched
Connect the frequency counter test cable to the BFO test point
(TP2). This will allow you to modify your filter and BFO settings if
necessary during normal operation.
If there are any missing chassis screws in the bottom cover, heat
sink, side panels, or front panel, install them now.
Plug the speaker into P5 on the RF board, just behind the on-off
switch, S1. The connector is keyed so that it can only be plugged in one
way.
Place the top cover onto the chassis and secure it using 8 chassis
screws.
K2 Manual 1/24/99 V.XC ©1999 Elecraft
Field test note: The embossed serial number labels did not arrive in
time for the initial field-test shipment. They will be sent to you at a later
date. For tracking purposes, your serial number has been assigned and
has been sent to you by e-mail.
Attach the self-adhesive serial number label to the rear panel of
the heatsink in the space provided.
Write the serial number on the inside cover of your manual.
This completes assembly of your K2. To get the most out of all the
K2’s features, please turn to the Operation section.
80
K2 Manual 1/24/99 V.XC ©1999 Elecraft
81
8. Operation
BA ND A ND
M E MO R Y
S E L E C TIO N
MO D E
IND IC ATO R
A N NU NC IAT O R S
BA ND +
S1
+
RC L
F
BA N D -
EL EC RAFT K 2
DIS P L AY
5
NUM E R IC
K E Y PA D
(1- 9)
T R A N SC E I V E R
M O DE
9 + 20 40
+
R F /A L C
A NT 1/2
RF
3
5
7
10
ALC
+
NB
A N T 2 P R E A TT
A
B
R IT
A /B
1
A =B
2
3
VOX
RE V
S P L IT
P R E /AT T
AGC
X F IL
+
X IT
4
5
6
ST O RE
TU NE
SPO T
CW R V
A F IL
M E NU
NB
R IT
X IT
MSG
+
E DIT
+
LE V E L
PF1
KE Y E R
A F G A IN
PO W E R
8
7
PF2
R EC
0
R F G A IN
R A TE
+
-1
0
+1
ON
OFF
LO C K
V FO
MIC R O P HO N E
JA CK
9
K 2 F R O NT PA N E L
N UM E R IC
K E Y PA D (0)
R IT /X IT
O F FS E T
PO W E R
O N/O F F
K2 Manual 1/24/99 V.XC ©1999 Elecraft
82
INTERNAL BATTERY
DISABLE SWITCH
ATU OPTION
TRANS VERTER OPTION
HOST ADAPTER
AND AUX I/O
INT. BATTERY
OFF
EXT. SPKR
ON
ANT 1
UNBAL
ANT 2
GND
AUX. I/O
ANTENNA TUNER
IN XVTR OUT
ANTENNA
KEY
12VDC
RCV. ANT.
+
-
12V BATTERY OR
POWER SUPLY
50ž
MAIN ANTENNA
(DO NOT USE IF
ATU IS INSTALLED)
ELECRAFT K2
SER. NO.
SEPARATE RECEIVE
ANTENNA (PART OF
160M/RXANT. OPTION)
K2 REAR PANEL
KEYER PADDLE,
EXT. KEYER, OR
HANDKEY
K2 Manual 1/24/99 V.XC ©1999 Elecraft
This section of the manual explains how to set up and operate the K2.
The first four sections provide a quick overview, and can later be used
as a reference:
§
§
§
§
Connections
Controls and Display
Using the Menu
Calibration Functions
The remaining sections are more tutorial in nature and go into detail
regarding specific types of operation:
§
§
§
§
Basic K2 Operation
CW Operation
SSB Operation
Advanced Operating Features
We recommend that you try out the various controls and functions as
they're introduced.
Note: The synthesizer, crystal filters, and a few other circuits must be
calibrated before operation. This is normally done during assembly
and test. Refer back to the RF Board Alignment sections if necessary
(Parts I, II, and III).
Connections
Power Supply
The K2 was designed to operate from a wide range of supply voltages
to enhance reliability and stability under field conditions. Any 9-15V
DC supply can be used, although 12-14V is recommended for best
performance. It is possible to operate from as low as 8.5V if
necessary. (In fact, a 9V alkaline battery can power the receiver in a
pinch.) Below 8.5V, synthesizer performance will be degraded, and
transmitting is not recommended.
83
Typical peak transmit current requirements are on the order of 1 amp at 5
watts, and 2 amps at 10W, when working into a well-matched antenna.
3A or more may be needed at the highest power settings when working
into a high-SWR load. (You can use voltage/current display mode to
monitor transmitter performance.)
Receive-mode current drain averages only 100-200mA depending on
how various menu parameters are set up. See Advanced Operating
Features for details on minimizing current drain during battery operation.
A heavy-duty (5 amp) mating connector for the K2’s power input jack is
provided with the kit.
Internal Battery: An optional 12V, 3AH rechargeable battery can be
installed inside the K2. To recharge the battery, simply connect the K2 to
an external power supply via the power jack, J3. This power supply must
be set for 13.8-14.0VDC or battery life will be reduced. You can also
operate the radio from this supply while it is charging the battery if it
has a high enough current rating.
If you must temporarily connect an external battery or a power supply
that is not set to 13.8-14.0V, you should turn off the internal battery
using the BATTERY switch on the upper rear panel. This will prevent
the external supply from reducing the internal battery’s usable life due to
underchaging. (The BATTERY switch is included as part of the internal
battery kit.)
External Battery: If an external battery is used, the internal battery
should be disabled (see above). Otherwise, the external battery may
supply charging current to the internal battery at an inadequate (low)
voltage, reducing the internal battery’s life.
K2 Manual 1/24/99 V.XC ©1999 Elecraft
Alternative Energy Sources: Operation directly from a solar panel
or other alternative energy source is possible, but the source must be
well regulated and filtered. The alternative energy source could also
be used to charge a battery, which in turn is used to power the
transceiver. A small (300mA) solar panel can keep the K2's internal
battery recharged indefinitely for casual operation, completely
eliminating reliance on AC power. Note that the voltage regulator
must be designed to turn its output off completely if the input voltage
drops too low to maintain 13.8-14.0V at the output.
Antenna
A well-matched 50 ohm antenna or an antenna tuner should be used
with the K2. If the antenna is not close to 50 ohms, power output
readings shown on the K2 display will be inaccurate. Some high SWR
conditions may result in excessive current drain.
If for any reason you’re not sure how well your antenna is matched,
do not operate at higher than 5W output. You can use the K2’s
voltage/current display to check voltage and current on transmit.
Keying Devices
Any type of hand key, bug, or external keyer can be plugged into the
KEY jack, or you can use the K2's built-in memory keyer. In all
cases, you must use a stereo plug with the keying device (a suitable
plug is provided with the kit). Please refer to the CW Operation
section for details on selecting a keying device and using the internal
keyer.
Microphone
A standard 8-pin microphone jack is provided on the front panel. This
jack is not pre-wired. Instead, there is a dual 8-pin jumper block on
the bottom of the front panel PC board that can be used to configure
the mic jack for nearly any compatible microphone. (The jumper
84
block and other mic interface components are supplied with the SSB
adapter.) Selected control functions are supported for some
microphones, including UP, DOWN, and FUNCTION.
(Additional details will be provided in the next manual revision.)
Headphones
Any type of mono or stereo headphones at nearly any impedance will
work with the K2. However, for best results we recommend high-quality,
8 to 32 ohm stereo headphones.
While it is possible to use a 1/4” to 1/8” adapter to handle phones with a
1/4” plug, the adapter tends to get in the way. You may wish to stick with
headphones that have a standard 1/8” plug, which includes virtually all
portable-stereo headphones. A right-angle plug is particularly well suited
to this application since the bulk of the plug and cable will be kept out of
the way, below the panel.
External Speaker
The K2 has a built-in, high-sensitivity 4 ohm speaker. You can also plug
in an external 4 or 8 ohm speaker at the “EXT. SPKR” jack on the upper
rear panel. (Elecraft plans to offer a an external speaker kit at a later
date.)
Option Connectors
A number of mounting holes are provided on the back panel of the K2 for
specific option connectors. For details, refer to the Internal Options
section of the manual.
K2 Manual 1/24/99 V.XC ©1999 Elecraft
Controls and Display
This section explains the function of the K2’s switches,
potentiometers, LED bargraph, and LCD.
Power Switch
The power switch is located at the lower-right corner of the front
panel. Push once to turn on (IN) and push again to turn off (OUT).
Push-button Switches and the TAP/HOLD Rule
In addition to the power switch, there are 16 light-touch push-button
switches on the front panel of the K2. Each of these switches has two
labels, one above the switch in white ink, and one below it in yellow.
Thus each switch has two functions, making 32 functions immediately
accessible. Note: If you tap or hold a switch associated with a missing
option module, you'll see a "NOT INST" (not installed) message on
the LCD.
To access an upper (white) switch function, TAP the switch briefly.
To access a lower (yellow) function, HOLD the switch down for
about one-half second. When you HOLD a switch in, you can release
it any time after an action has taken place, usually indicated by an
LCD message.
85
functions as an S-meter on receive, and on transmit displays power
output. If you have installed the SSB adapter, you can switch to ALC
rather than RF display on transmit (see SSB operation).
Power-Up Messages: The LCD will display ELECRAFT for two
seconds on power-up if the self-test passed. You can tap any switch
during this time to check the firmware revision (see Advanced Operating
Features). After displaying ELECRAFT for two seconds, the display will
show the operating frequency and mode, as well as other indications (see
below).
If a problem is detected at power-up, the display will show INFO 100 or
a similar message. The numbers shown in INFO messages correspond to
the numbered paragraphs in the Troubleshooting section. Some INFO
messages indicate a serious problem that should be investigated before
continuing operation.
Mode Indicator: A lower-case letter at the right end of the display tells
you what operating mode the K2 is presently in: ‘C’ (CW), ‘L’ (LSB),
‘U’ (USB), or ‘R’ (RTTY). If a small bar appears above the letter C, it
means that the CW sideband is inverted. We refer to this as CW reverse
operation.
The mode indicator will also flash very slowly when the transceiver is in
a special operating mode:
§
Even though the TAP/HOLD distinction can be inferred from the
switch label, we’ll use the unambiguous words tap and hold rather
than press when referring to switches.
§
LCD and Bargraph Meter
The K2 has an eight-character backlit LCD, plus a 10-segment LED
bargraph. The LCD shows the operating frequency and other
information depending on selected display mode. The bargraph
When you're using CW, holding the VOX button alternates between
TEST and OPERATE. When TEST is selected, keying activity or
message playback activates the sidetone but does not transmit. The
mode letter (C) will flash as a reminder.
When you're using LSB or USB, holding VOX alternates between
PTT and SPEECH. When SPEECH (voice-activated transmit) is
selected, the mode letter (L or U) flashes.
K2 Manual 1/24/99 V.XC ©1999 Elecraft
86
Annunciators: In addition to the eight 7-segment characters, the LCD
provides eight Chevron-shaped annunciators, or status indicators.
Annunciators will be turned on or will flash slowly under certain
conditions. For each annunciator there is also a small text label on the
panel. The annunciators provide the following indications:
Potentiometers
NB
ANT2
PRE
ATTN
A
B
RIT
XIT
Turning this control CCW (counter-clockwise) decreases receiver RF
sensitivity. At the same time it increases the bargraph S-meter indication
to remind you that you’re not at full receive sensitivity. The farther CCW
the control is set, the stronger a signal must be before it results in a meter
deflection above the selected level.
noise blanker on (requires noise blanker option)
antenna 2 selected (requires ATU option)
pre-amp on
attenuator in (-10dB)
VFO A selected (flashes in SPLIT mode)
VFO B selected (flashes in SPLIT mode)
RIT turned on (flashes)
XIT turned on (flashes)
Decimal Points: The decimal point to the right of the 1kHz digit is
always on when the display is showing operating frequency. It will
flash slowly if the VFO is locked. The decimal point to the right of the
MHz digit is flashed during scanning, and the decimal point to the left
of the mode letter will flash slowly as a reminder if you turn off AGC.
(See Advanced Operating Features.)
AF GAIN
receiver audio level
RF GAIN
receiver RF level13
KEYER
keyer speed control14
When you turn this knob, keyer speed in words per minute (WPM) will
be displayed. The speed can be set from about 9 to 40WPM.
POWER
power output control
When you turn this knob, transmit power output will be displayed in 0.1
watt increments from 0.0 to about 12.0 watts. See Basic K2 Operation
for details on power output settings.
OFFSET
RIT/XIT offset
This control provides a range of +/- 1.2kHz in 10Hz steps when RIT
and/or XIT is enabled. (For wider splits, use SPLIT mode.) Varying
this control automatically selects the 10Hz/step tuning rate.
13
As in many transceivers, this control actually varies the I.F. gain.
The KEYER and POWER controls can be used when transmitting, but
setting resolution will be reduced to improve RF noise immunity.
14
K2 Manual 1/24/99 V.XC ©1999 Elecraft
87
Switch Functions
Switch functions are listed here in short form for reference, but you’ll
also find switch usage details in sections that follow. If a switch tap or
hold must be followed by a single-digit number, the range of valid
numbers is shown in parentheses.
A/B VFO
REV
TAP
HOLD
select A or B VFO
quick alternate VFO check
AGC
CW RV
TAP
HOLD
select FAST/SLOW AGC15
select normal/opp. CW RX
BAND +
RCL
TAP
HOLD
next higher band
recall memory (#0-9)
XIT
PF2
TAP
HOLD
turn on XIT
programmable function 2
BAND –
STORE
TAP
HOLD
next lower band
store memory (#0-9)
A=B
SPLIT
TAP
HOLD
both VFO’s set to current VFO
SPLIT/NORMAL xcv
MENU
EDIT
TAP
HOLD
enter the menu
edit parameter
XFIL
AFIL
TAP
HOLD
select xtal filter FL1-3
set audio filter mode
DISPLAY
RF/ALC
TAP
HOLD
select display mode
select TX bargraph mode
MSG
REC
TAP
HOLD
play CW message (#7-9)
record CW message (#7-9)
ANT1/2
TUNE
TAP
HOLD
select antenna 1/2
key transmitter
Numeric Keypad
NB
LEVEL
TAP
HOLD
noise blanker OFF/ON
select noise blanker mode
RATE
LOCK
TAP
HOLD
VFO 10/50/1000 Hz/step
lock/unlock VFO (DP flashes)
MODE
VOX
TAP
HOLD
select op mode (C,L,U,R)
VOX/PTT, OPER/TEST
PRE/ATTN
SPOT
TAP
HOLD
turn on preamp or atten.
CW audio spot signal on/off
RIT
PF1
TAP
HOLD
turn on RIT (ann. flashes)
programmable function 1
The ten switches to the right of the VFO serve as a numeric keypad for
frequency STORE/RCL, direct frequency entry, and CW message
record/playback. The RATE/LOCK switch is used for digit ‘0’, and the
other nine switches are used for digits ‘1’ through ‘9’ as labeled to the
right of each switch.
15
AGC can also be turned off; see Advanced Operating Features.
K2 Manual 1/24/99 V.XC ©1999 Elecraft
88
Using the Menu
Menu Functions
The K2 menu is used for settings that are not changed very often. To
access the menu, tap the MENU switch.
All menu functions are listed below for reference. Details on specific
functions can be found in the Calibration Functions, Basic K2 Operation,
CW Operation, and SSB Operation sections. Menu parameter settings
are stored in EEPROM so they will not be lost when you turn off the K2.
When you enter the menu, the display will show the menu entry last
used, with its name underlined. For example, you might see: LCD
DAY, indicating that the LCD is in “day” mode (i.e., backlight off).
You can select a different menu entry by turning the VFO knob or by
tapping the BAND+ and BAND- switches. This process of moving
through the menu entries is referred to as scrolling.
Once you’ve selected a menu entry to change, hold the EDIT switch
to modify the parameter. This will cause the parameter to be
underlined, rather than the menu entry name. In the case of LCD, the
parameter can be DAY or NITE. As with the menu entries
themselves, parameters can be changed with either the knob or the
BAND+/- switches.
When you’re finished with the parameter change, tap MENU to return
to scrolling. Another tap of MENU will return you to normal
operation.
The Edit Shortcut
If you know that the menu entry you want is the last one you
accessed, you can use the edit shortcut: just jump right into edit mode
by holding EDIT. You can change the parameter as usual, then exit
by holding EDIT once more. (Tapping MENU at this point will return
to menu scroll mode as usual.)
ST L
ST P
DLAY
INP
IAB
SSBA
SSBP
LCD
GRPH
OPT
TRN
ATU
RANT
CAL
PF1/PF2
sidetone level: 0-250 (sidetone volume)
sidetone pitch: 0.40 to 0.80kHz in 10Hz steps
QSK (break-in) delay: 0.00 to 1.50 seconds
(0.01 sec increments from 0.00-0.10,
0.10 sec increments from 0.10-1.50)
CW input selection:
PDLn (internal keyer, paddle normal)
PDLr (internal keyer, paddle reversed)
HAND (handkey or external keying device)
iambic mode: A or B
SSB audio level (mic gain): 0-31
SSB speech processor level: 0-31
DAY (backlight off, bargraph very bright) or
NITE (backlight on, bargraph normal brightness)
LED bargraph selection: OFF, DOT or BAR
(bargraph OFF applies only to receive mode;
see Advanced Operating Features)
receiver optimization: PERFormance or BATTery
(See Advanced Operating Features)
internal transverter control: OFF or ON
automatic antenna tuner control: OFF or ON
receive antenna switch: OFF or ON (per-band)
(See Advanced Operating Features)
calibration submenu (see Calibration Functions)
Programmable Function buttons
(see Advanced Operating Features)
K2 Manual 1/24/99 V.XC ©1999 Elecraft
89
Menu Defaults
Calibration Function Defaults
When you first power-up the K2, the following defaults are setup:
When you first power-up the K2, the following Calibration defaults are
setup:
Bargraph mode = DOT; sidetone level = 40; sidetone pitch = 0.60
(600Hz); iambic mode A; QSK delay = 0.02 (20ms); LCD = NITE
(backlight on, bargraph low brightness); input device = HAND; OPT
= PERF (optimization for performance rather than battery);
programmable functions: PF1 = ST L, PF2 = ST P.
Calibration Functions
The CAL menu entry, short for calibration, is actually a separate
menu in itself, providing functions that are used primarily for
alignment and test. However, you may use some of the CAL functions
more often. For example, CAL FIL is a powerful function that allows
you to customize filter selections for each operating mode.
To use CAL, enter the menu and change the CAL parameter from
OFF to one of the functions listed below. Hold EDIT a second time to
initiate the calibration function. Complete details on how to use each
CAL function are provided below.
CAL Functions - Quick Reference
OFF
FCTR
FIL
PLL
BIAS
S LO
S HI
-frequency counter
filter settings
VFO linearization
driver bias level
S-meter zero
S-meter sensitivity
BIAS = 144; S LO = 178; S HI = 27. Also see Filter Settings, below, for
crystal filter defaults.
Frequency Counter(CAL FCTR)
Before using the counter (CAL FCTR), you must connect the internal
frequency counter input to the signal to be counted. A short test cable is
provided for connecting the counter input to any of several internal K2
signals during alignment. Once you’ve connected the test cable, use the
menu to select the CAL FCTR function. Hold EDIT again to enable the
counter.
It is also possible to mount a connector of your choice on the rear panel
of the K2 and use the frequency counter externally (see Modifications).
Note: See Advanced Operating Features for suggestions on how to
accurately calibrate the frequency counter.
K2 Manual 1/24/99 V.XC ©1999 Elecraft
Filter Settings (CAL FIL)
CAL FIL is used to specify crystal filter bandwidths and BFO offsets
for each operating mode. In most cases you’ll start with the default
narrow/medium/wide filter settings and modify them slightly to
achieve the best filter sound. An alternative, discrete passband tuning
(DPT), is covered at the end of this section.
Note: This section applies to both CW and SSB reception using the
variable-bandpass crystal filter. However, if you have the SSB
adapter installed, chances are you’ll use the specialized filter supplied
with that module for SSB reception.
Figure 8-1 shows representative filters for CW-normal mode. (The
horizontal axis is frequency.) What you actually hear is the difference
between the carrier frequency and the BFO (beat frequency
oscillator). For example, if you were using FL2 or FL3 and were
tuned to the signal shown at 4913.0 kHz, you’d hear a 1000Hz signal.
But you would not hear this signal if you were using FL1, since its
upper cut-off frequency is below the signal.
FL1
BFO
1,2,3
FL2
Signal
(4913.0)
(4912.0)
Figure 8-1
FL3
90
K2 Manual 1/24/99 V.XC ©1999 Elecraft
91
In the previous example, the BFO was set for the same frequency for
all three filters. Figure 8-2 shows the same filters as used on CW
Reverse (opposite-sideband CW). In this case the BFO must be at a
frequency above each filter, so the BFOs settings are all different. The
K2 compensates for these changes in BFO setting, however, so when
you use CW reverse you’ll still hear the 1000Hz signal shown in
Figure 8-1, and the filters will function identically.
FL1
FL2
BFO
1
FL3
BFO
2
Figure 8-2
BFO
3
K2 Manual 1/24/99 V.XC ©1999 Elecraft
92
Filter Defaults (Narrow/Medium/Wide)
On initial power-up the filters will be set as shown below. These
values give you narrow/medium/wide filters (FL1/2/3) for each mode.
You will probably need to modify at least the BFO settings due to
unit-to-unit component variations.
Mode Filter Setting
FL1
CW Normal
40
CW Reverse
40
RTTY
40
LSB
180
USB
180
FL2
70
70
70
200
200
BFO Setting
FL3
BF1
150
159
150
187
150
150
230
159
230
205
BF2
159
190
150
159
215
BF3
159
202
150
159
230
Interpreting Filter Numbers: The numbers in the table above can
each have values from 0-255. For Filter Settings, the smaller the
value, the more narrow the bandwidth will be. (A filter setting of 70
corresponds to a moderately narrow CW bandwidth.) For BFO
Settings, smaller numbers place the BFO farther below the filter
passband. (A BFO setting of 159 puts the BFO just below the filter,
and is about the average setting you'd use for CW-Normal or LSB
operation.)
Modifying Filter Settings: The following example shows how to
change the BFO setting for the first CW filter (FL1). Before you
attempt to modify any filters, make sure the frequency counter test
cable is connected to the BFO test point (TP2). Also, connect an
antenna and adjust the AF gain so that you can hear some noise while
adjusting the settings.
1. Select CAL FIL in the menu; hold EDIT to confirm.
2. The display will now be similar to "FL1 040c". In this case it
shows that CW-normal filter FL1 is set to 40.
3. Tap BAND- to display the BFO setting rather than the filter
setting. The display will change to "BF1 159c". This shows that
the BFO setting for CW filter FL1 is 159. (Tapping BAND+ will
return to the filter setting.)
4. Sweep the BF1 value through the entire 0-255 range using the VFO
knob. You’ll hear the pitch of the noise change. At some point in the
adjustment range you’ll hear the pitch go very low and then to zero-this is where the BFO has passed through the center of the filter.
Note the value of this zero-pitch number (typically 170-180).
5. Set the BF1 value to a number that is lower than the zero-pitch
number (this is required for CW Normal mode). For CW normal
mode, a number between 150 and 165 is generally about right, but
you’ll have to set it “by ear” for the best sound. Ideally, you’ll want a
BFO setting that works best with your sidetone pitch. This may
require some experimentation.
6. Tap the MENU button to exit CAL FIL. The built-in frequency
counter will then measure, display, and record the new BFO
frequency for filter FL1 (roughly 4913kHz).
When you’re using CAL FIL you can modify more than one filter at a
time. For example, in step 6 above you could have tapped XFIL to switch
to BF2 rather than return to normal operation. Similarly, you can hold
CW REV to change to CW Reverse, and tap MODE to change to LSB,
USB, or RTTY.
Important notes on Filter Settings:
§
§
§
When setting up filters for CW Normal, LSB, and RTTY:
position the BFO below the zero-pitch number (see step 4, above).
Generally, you’ll use the same BFO setting for all three filters for
these modes as shown in Figure 8-1.
When setting up filters for CW Reverse and USB:
position the
BFO above the zero-pitch number. The BFO settings will generally
be different for all three filters in these modes, because the upper
edge of the filter passband changes as bandwidth changes. An
example was shown in Figure 8-2.
Since the K2 inverts the sideband, the LSB and USB filters are
swapped on 15 meters (21 MHz) and above. This has two
implications: (1) to avoid confusion, always do LSB and USB filter
K2 Manual 1/24/99 V.XC ©1999 Elecraft
93
adjustments on one of the lower bands (160-17m); (2) if you use
DPT (see below), you’ll have to set up both the LSB and USB
filters this way to maintain consistency on all bands.
Discrete Passband Tuning (DPT): An alternative to setting up
filters for narrow/medium/wide is to set them up for discrete
passband tuning (DPT). In this case, you'll set up the three filters for
a particular mode so that their bandwidths are all the same, but their
BFO settings are different. The filters can then be used in a manner
similar to "Passband Tuning" or "I.F. Shift", but with discrete steps
(FL1-3) instead of a continuous control.
Figure 8-3 shows the relationship between filter and BFO settings
when CW-Reverse is configured for DPT. The filters are all set for
the same bandwidth, but BFO 1, 2, and 3 are now at various distances
from the filters. Thus the center frequency of the passband shifts as
you move from one filter to the next.
FL1,2,3
BFO
1
BFO
2
Figure 8-3
BFO
3
To get a feeling for how DPT sounds, try using the following
configuration for the CW Reverse and LSB filters (your optimal settings
will be somewhat different). Keep the CW Normal and USB filters set up
as before for comparison. Remember, the LSB and USB filters are
swapped on 15m and above, so if you decide to use DPT for SSB
reception you should set up both the LSB and USB filters in this way.
Mode Filter Setting
FL1
CW Reverse
70
LSB
200
FL2
70
200
BFO Setting
FL3
BF1
70
194
200
162
BF2
198
159
BF3
203
155
94
Repeat steps 4-8 for each remaining band.
VFO Linearization (CAL PLL)
16
and must be used once on each band.
nonlinear on bands that are not yet calibrated. You can repeat CAL
(One reason you might re-run CAL PLL is after calibrating the
frequency counter to WWV; see Advanced Operating Features.)
CAL BIAS allows you to set the bias current in the driver stage (Q6) on
transmit. Normally you'll leave this setting at the default. (Alternative
revision of the manual.)
S-meter Zero Level (CAL S LO)
step at room temperature (approx. 20-25°
linearity will then be acceptable over a wide range of operating
temperatures.
1.
2.
3.
4.
1.
2.
3.
turned off
5. exit CAL mode by tapping MENU
test point (TP1).
4. Exit the menu if you were using it.
5. Switch to the band you wish to calibrate. (If you plan to calibrate
all bands, keep a checklist to avoid skipping any.)
Set the VFO to a frequency that is
a 100kHz boundary
near the middle of the desired tuning range (e.g., 7100.10).
Enter the menu and select CAL PLL; hold EDIT a second time to
8.
short alert tone and see the message "END" on the LCD. You can
then tap any button to return to normal operation. Note: If you
Troubleshooting.
16
What you're actually calibrating is the relationship between the PLL
Circuit Details for a complete explanation of how the frequency synthesizer
works.)
S-meter Sensitivity (CAL S HI)
1.
2.
3.
4.
barely turned off
5. exit CAL mode by tapping MENU
You may want to experiment with this setting to match the K2's S-meter
no absolute standard for S-units. S-meter indications are best used as a
relative indication of signal strength or signal-to-noise ratio.
K2 Manual 1/24/99 V.XC ©1999 Elecraft
Basic K2 Operation
Receiver Configuration
When using bands above 7 MHz (40 meters), you'll probably want to
use the preamp (about +12dB) to improve the overall signal-to-noise
ratio. The preamp is seldom needed at 7Mhz or below due to high
atmospheric noise. However, if you use an inefficient antenna on these
bands, such as a mobile whip, the additional gain may be needed.
If you experience very strong in-band interference, you can turn off
the preamp. If necessary, an additional 10dB of attenuation can be
switched in by turning on the attenuator.
95
active as well depending on installed options. If you have the host
interface adapter option installed, a time display mode will be available
that shows UTC.
In frequency display mode, the LCD will show the operating frequency,
mode indicator, and any annunciators that are enabled. This is the display
you’ll use most often.
In voltage/current display mode, the LCD will show supply voltage in
0.1V increments and supply current in 0.02A increments. Voltage/current
display is useful for monitoring battery condition and transmitter
performance. It can also be used in conjunction with a simple voltage
probe to check DC voltages inside the K2.
See Advanced Operating Features for details on additional receiver
configuration issues.
A two-position slide switch on the control board, S1, selects either 12V
monitoring or the voltage probe. If the voltage/current display shows 0.0
volts, it is likely that you have S1 in the probe position.
LCD and Bargraph Configuration
Frequency Selection
If you're operating outdoors, use the menu to select LCD DAY, which
turns off the LCD backlight and puts the LED bargraph into highbrightness mode. Indoors or at night, use LCD NITE, which turns the
backlight on and reduces the bargraph brightness.
The basic K2 kit covers the 80 through 10 meter bands. If you have the
160m/RXANT option installed, 160 meters will also be available. If you
have a transverter installed, it will be the next band above 10 meters. You
can also tune well above and below most bands, and can listen to WWV
at 10, 15, and 20Mhz.17
You have a choice of OFF, DOT, or BAR for the LED bargraph. If
you select DOT, just one bargraph segment representing the current
meter level will be illuminated. If you select BAR, all LED segments
to the left of the current level will also be illuminated, resulting in a
more visible display. OFF mode turns off the bargraph completely
during receive (see Advanced Operating Features).
Display Modes
Tapping the DISPLAY button alternates between frequency display
mode and voltage/current display mode. Other display modes may be
You can change bands in one of three ways:
§
17
tap BAND+ or BAND-
The receiver is not intended to be general coverage; narrow band-pass filters
are used at the front end to reject out-of-band signals. While it is possible to
tune continuously from one band to another using the VFO, band switching
will not take place as you cross into another band. If you attempt to tune too
far outside an available band, receiver sensitivity and transmit power will
greatly decrease, and at some point the synthesizer will lose lock. This
behavior will be modified in a subsequent firmware release.
96
§
§
hold RCL (memory recall); see below
use direct frequency entry; see below
K2 Manual 1/24/99 V.XC ©1999 Elecraft
Whenever you change bands or recall a frequency memory, your
current operating frequency, mode, and a number of other band-
number of the memory you wish to recall. In both cases you can cancel
the operation by tapping any non-numeric switch.
update also occurs periodically if you’ve moved the VFO (see Backup
Timer, below). The parameters that are saved on a per-band/per-
hold rather than
a numeric keypad digit when doing
either a store or recall, you will initiate scanning. See Advanced
§
§
§
§
§
§
§
Direct Frequency Entry: To do direct frequency entry,
both
BAND+ and BAND- simultaneously. When you see – – –
LCD, release the BAND switches, then enter the target frequency using
the numeric keypad. To enter a frequency in the 160 meter band, you
§
10Mhz, you need only enter 4 digits (e.g., 7040 requires no leading '0').
capability)
Receive antenna on/off (see Advanced Operating Features)
Default Frequency Memories:
band memory is preset as follows:
There are three possible results from using direct frequency entry, as
§
within the current band, only the current
§
§
§
§
VFO A is set to 100kHz above the band edge
VFO B is set to the CW QRP frequency for that band
Other defaults include: CW mode; VFO A; fast AGC; preamp
ON above 40 meters and OFF on 40m and below; noiseblanker
results, and the entire configuration for the target band will be
loaded, except that the current VFO will now be at the frequency you
§
you’ll be switched to the closest available band, and the frequency
will be set to the one last used on that band. For example, if you try
General memories #0-8 are preset to the same values as the 160-10
meter band memories, respectively.
Ten frequency memories are provided, numbered 0
through 9. Each memory stores the same information that is stored
To store the current setup in a frequency memory, hold STORE until
you see "ENT 0-9," then tap one of the numeric keypad switches. To
the K2 will switch to 40 meters and setup the VFOs as they last were
on this band.
K2 Manual 1/24/99 V.XC ©1999 Elecraft
98
Tuning Rates and VFO Lock
Filter Selection
Three VFO tuning rates are provided, selected by tapping the
RATE/LOCK switch. Tuning rates include 10Hz, 50Hz, and 1kHz
per step, which equate to 1kHz, 5kHz, and 100kHz per turn.
50Hz/step is ideal for casual "hunting," while 10Hz/step provides
very fine tuning. 1kHz/step is useful for quickly moving to another
part of the band.
Each operating mode provides three user-programmable filter settings:
FL1, FL2, and FL3. The filter number is selected with the XFIL switch.
Each time you tap XFIL, the next filter will be selected and the display
will flash the number of the new filter. Even though the filter number is
not continuously displayed, it won’t be long before you know just by
listening which filter is selected. The last filter selected for each mode is
stored in EEPROM.
The frequency display changes to remind you of the current tuning
rate. At 10Hz/step, two decimal places are shown (100Hz and 10Hz).
When you select 50Hz/step, the 10Hz digit is blanked. When you
select 1kHz/step, both decimal places are blanked.
The VFO can be locked (frequency change disabled) by holding the
RATE/LOCK switch until "LOC" is displayed on the LCD. The
decimal point will then flash slowly as a reminder. Holding the switch
again cancels lock and displays "NOR" (normal).
Mode Selection
Tap MODE to cycle through the four operating modes, noting the
change in the mode indicator letter. The last operating mode selected
for each band is stored in EEPROM.
Refer to CW Operation, SSB Operation and RTTY Operation for
more details on using each of these modes.
You can set up your filters in two different ways, depending on your
needs:
§
§
narrow/medium/wide
discrete passband tuning (DPT)
You can also use a combination of these settings. (See Calibration
Functions for more information on setting up filters.)
Using Narrow/Medium/Wide Filters: If you've set up your filters in
narrow/medium/wide format, which is the default, simply select a filter
that provides the desired level of interference rejection. Narrower
bandwidths will improve the signal-to-noise ratio. On a quiet band or
when searching over a wide range, try a wider bandwidth setting.
You can modify your filter settings even in the field by using the CAL
FIL function. For example, you might want to narrow all three filters
somewhat for contest operation.
Using Discrete Passband Tuning (DPT): If you have configured your
filters for DPT, you can select one of the three filters based not only on
interference rejection but also on overall sound of the filter passband.
This is especially useful for SSB reception, where you can shift the filter
up or down in relation to the received signal to improve speech
intelligibility.
99
Power Control
Note: When you first power-up the K2, VFO B on each band will be prerange of the control is about 0 to 12 watts in 0.1–watt steps. After
adjusting the POWER control, you can send a few CW characters or
new level.
The POWER control sets only the
power, which may
exceed the
power that the transmitter can achieve for a given
supply voltage, SWR, etc. To see
power output, use the TUNE
switch. During TUNE, the display always shows the actual power
Split and Reverse Operation
Split
This is useful for DX work, since many DX stations will ask you to call
them above or below their carrier frequency to avoid interference. To
LCD. Holding SPLIT in again will display "NOR" (normal). The active
VFO annunciator (A or B) will flash slowly when you’re in SPLIT mode
power displayed will be accurate to within about 10% if the load at
the antenna is matched (50 ohms).
transmit frequencies are different. Also, each time you transmit when in
SPLIT mode, the transmit frequency is displayed for a minimum of 1/2
recommended. Current drain may be excessive, and the CW keying
waveform may change. To be safe, reduce the power setting if you’re
When you're using split, you can switch between your transmit and
receive frequencies by tapping A/B. However, there are times when you
or if the voltage/current display shows that the current drain is too
high.
In this case you can hold in the REV switch (reverse), which temporarily
swaps the VFOs. When you release REV, the LCD will return
inserted between the K2 and the antenna. (The optional receive
antenna switch may be helpful in this case; see Advanced Operating
VFO Selection
There are two VFOs, A and B, which are maintained on a per-band
annunciator will be turned on. To set the unused VFO equal in
frequency to the current VFO, tap A=B. The currently-selected VFO
running SPLIT (see below).
operators can simultaneously hold in the REV switch and adjust the VFO
knob--all with one hand--to quickly find a clear spot to transmit.
K2 Manual 1/24/99 V.XC ©1999 Elecraft
100
RIT and XIT
current operating frequency in EEPROM. As long as you stay on a
particular frequency, no further updates will be done.
You can turn on RIT (receive incremental tuning) by tapping the RIT
switch. The RIT annunciator turns on and flashes slowly to remind
you that transmit and receive frequencies are different. The knob
below RIT and XIT controls the receive offset (+/- 1.2kHz). The front
panel labeling shows the approximate offset, but the exact offset can
be determined by comparing the frequency displays with RIT on and
off.18
By backing up the frequency data only when you move and then stop for
at least 30 seconds, the last significant frequency that you were on is
saved--i.e., the last one where you may have had a QSO or listened for a
while. This is similar in concept to the “last channel recall” button on a
TV remote control.
When XIT is turned on it works similarly, except that the transmit
frequency is varied with the offset control. This can be useful for
small-split operation (for example, when a DX station you're listening
to says to call "UP 1" kHz), or to adjust your transmitted frequency at
the request of another station. Transmitted frequency is not displayed
at all times, so if you need to determine the exact setting of the offset
control when using XIT, you can briefly turn on RIT.
It's OK to have both XIT and RIT on at the same time. In this case
the offset control can be thought of as an extension to the main tuning
knob, but covering only a small frequency range.
As with SPLIT, if you have RIT or XIT enabled, the transmit
frequency will be displayed when you transmit and the receive
frequency will be restored a minimum of 1/2 second later.
Backup Timer
While you're moving the VFO, a 30-second data backup timer is
being continuously re-started. Once you have completely stopped
tuning the VFO for at least 30 seconds, the K2 will then save your
18
We did not include detent on the offset knob because experience has
shown that knob detent mechanisms degrade over time, making it difficult
to adjust the offset near the zero point. However, you can always return the
offset knob to the zero point by simply matching the RIT-on and RIT-off
frequency displays.
The K2's frequency backup method is quite different from the way many
other radios operate. Typically, a battery-backed-up RAM is used, and
your current operating frequency is updated continuously. However, we
chose to use a high-reliability EEPROM memory instead (good for over 1
million writes, so you can't wear it out). The advantage to this method is
that the backup battery is eliminated. This is a very high failure-rate item
in many devices, particularly if a battery socket is used.
CW Operation
The K2 provides a number of features specifically for the CW operator:
§
§
§
§
§
§
§
§
§
fast I.F.-derived AGC with fast/slow/off control
full break-in operation with no relays
accurate control of CW speed, sidetone volume, and sidetone
pitch/receive offset
built-in memory keyer with Iambic modes A and B, plus three
programmable message buffers and auto-repeat
"smart" scanning (see Advanced Operating Features)
software-selectable paddle selection (normal or reverse)
multiple, user-configurable crystal filter bandwidths and CW reverse
(opposite sideband CW)
dedicated SPOT switch for accurate matching of received signals
optional low-noise analog audio filter
This section explains how to get the most out of the K2's CW features.
K2 Manual 1/24/99 V.XC ©1999 Elecraft
The SPOT Switch
Keying Device Selection
The SPOT switch can be used to zero-in on received signals or to test
A single connector in the back is provided for your keyer paddle, hand
the menu.
menu entry as explained in the MENU section. You must use a
STEREO plug, even if you use a handkey or external keyer. This
When you use SPOT, the receiver audio will not be muted. This allows
middle contact on the plug (often called the “ring” contact) is only
used with keyer paddles.
that of the sidetone, which guarantees that you’ll be very close to the
station’s frequency if you call. (Exception: If you’re using RIT, XIT, or
just the normal transmit/receive offset.)
plug’s “tip” contact, and DASH to the “ring” contact. If your paddle
is already wired backwards from this, or if you’re left-handed, use the
needed.
Unfortunately, matching audio pitch is a little tricky for some operators.
hearing seems to “disappear” under the sidetone--that is, until you can’t
hear any difference between the two. When this happens, you’ll know the
Basic CW Setup
indicator changes to 'C'. You may also want to select one of the three
filter settings at this time using the XFIL switch. FL1 is typically
If you want to try out the keying without actually transmitting, hold
the VOX switch until the display shows TEST. The ‘C’ on the LCD
VOX switch in again returns to OPERATE.
Key the rig in TEST mode and listen to the sidetone volume and pitch.
The pitch can be changed using the ST P entry (sidetone pitch).
These functions are performed often, so you might want to assign
Some first-time SPOT users end up tuning the received signal to a
harmonic of the sidetone pitch, or vice-versa. But if you keep the
K2 Manual 1/24/99 V.XC ©1999 Elecraft
Using the Internal Keyer
In addition to sidetone level and pitch, three menu entries are provided
to set up the keyer:
§
§
§
IAB allows you to select Iambic mode A or B (mode A is similar
to Curtis mode A; mode B is similar to Super CMOS Keyer III
mode B)
INP selects paddle normal (PDLn), paddle reverse (PDLr), or
handkey/ext. keyer (HAND)
dLAY allows you to set fast or slow break-in delay (a setting of
0.05 is excellent for casual full-break-in operation)
All of these settings are stored in EEPROM, so you won’t lose them
when you turn power off.
Use the KEYER control to select the desired CW speed. The display
shows the speed in WPM as soon as you start turning the knob. You
can even adjust the speed while transmitting.
Message Memories
To record a message: hold REC, and when prompted tap a numbered
switch (7, 8 or 9) to select one of the three message buffers. (You can
cancel message record before it starts by tapping any non-numeric
switch.) The display will then show REC 084, indicating that 84
bytes of storage are available. This number will count down towards
0 as soon as you start sending. Tap REC immediately upon
completing the message to exit record mode.
To play back a message, tap MSG, then tap a single digit (7, 8 or 9).
Use TEST mode (via the VOX switch) if you want to listen to the
message without transmitting. Message play can be canceled at any
time by hitting another switch or by tapping the key or keyer paddle.
102
Auto-Repeat: Any of the three message memories can be auto-repeated
when played. To initiate auto-repeat, tap MSG as usual, but HOLD the
numeric switch (7, 8 or 9) rather than TAPping it. The message will then
play back continuously until you tap any switch or hit your key or
paddle.
The length of the pause between messages during auto-repeat is set
during message record. For example, if you want a 3-second delay, wait
3 seconds after completing the message before you stop recording. The
delay time is also proportional to the CW speed setting. If you included a
3-second delay and recorded your message at 20WPM, the delay will be
only 1.5 seconds if you play it back at 40WPM.
CW Reverse
CW Reverse capability--that is, the ability to listen to CW using the
opposite sideband--has two primary uses:
10. allows you to choose whether signals increase or decrease in pitch as
you tune up the band19
11. provides you with an additional three CW filter settings that can be
used in various ways to reduce interference (see Calibration
Functions)
To switch to the opposite sideband, hold the CW RV (CW reverse)
switch. A bar will appear above the mode character (‘C’) on the LCD.
You can then use XFIL to select one of the filters configured in CAL FIL
for CW reverse.
19
The single-conversion mixing scheme used in the K2 causes sideband
inversion on 15-10 meters, resulting in the following idiosyncrasy: on 160-17
meters in CW normal mode, the pitch of signals goes up as you tune higher in
frequency, while on 15-10 meters in normal mode, the pitch goes down. (CW
reverse mode inverts this characteristic.) However, we chose not to
automatically switch to CW reverse on 15-10m, since the CW reverse filters
"sound" slightly different due to passband asymmetry.
K2 Manual 1/24/99 V.XC ©1999 Elecraft
103
§
Whenever you change the sidetone pitch using the ST P menu entry,
you’re also changing the CW receive offset. The two always match
stations at same pitch as the sidetone, your transmitted signal will be
right on that station’s frequency. This is especially important when
Use the CAL FIL menu function to setup three filter bandwidths for
LSB and 3 for USB. For instructions and recommended settings see
§
Nearly all SSB operation on 14MHz and above is on USB, while
LSB is used on 7MHz and below. For AM reception you can use
symmetrical at wide bandwidths so you may find that one sideband
sounds somewhat better than the other.
To see how the receive offset tracks the sidetone pitch, try this
experiment. First, use the SPOT switch to tune in a station at your
Operating Features).
use the ST P entry to change the pitch. As soon as you exit the menu,
you’ll notice that the station you were listening to has also been
Note that changing the sidetone pitch does not shift the BFO in
relation to the crystal filter. This will not be a problem if you're using
SSB Transceive
Note: If you transmit using LSB or USB modes with the basic (CW-only)
K2, keep in mind the following:
using a very narrow filter, then change your sidetone pitch by a large
amount, you may want to use CAL FIL to shift the BFO so that the
If you select LSB or USB mode and hit the DOT paddle or a hand
SSB Operation
receive offset will be set to zero. (The key jack’s DOT line doubles
as the mic jack’s push-to-talk line when the SSB adapter is installed.)
When you hold the TUNE button, the K2 switches internally to CW
Even if you have not installed the SSB adapter, you'll find this section
with any mode selected.
on a CW-only K2, as well as SSB and RTTY transceive operation.
SSB and AM Receive
by using a wide-band setting of the variable-bandwidth crystal filter.
K2 Manual 1/24/99 V.XC ©1999 Elecraft
104
RTTY (Radio Teletype) Operation
Scanning
An “R” (RTTY) mode setting is provided so that the variable crystal
filter can be set up specifically for receiving RTTY. This may be
useful if you wish to connect a TU (Terminal Unit) to the K2’s audio
output to decode and display RTTY signals. To set up filters and
BFO offsets for receiving RTTY, refer to the Calibration Functions
section.
The K2's scanning feature lets the K2 tune any band segment
continuously, keeping the receiver audio squelched until signals of
interest are found. Scanning works for both CW and SSB signals, and
when properly set up will not respond to carriers (key-down signals with
no modulation). It is especially useful for automating "hunt and pounce"
(starting at one end of a band and working up) and for monitoring your
favorite band.
Typically, AFSK (audio frequency shift keying) is used to generate
RTTY signals. To transmit AFSK you'll need the SSB adapter. (More
details next manual revision.)
To use scanning:
§
FSK (using directly modulation of the carrier frequency in CW mode)
may be supported in a future release of the K2 firmware.
RTTY-Mode Controls
§
§
RTTY mode is identical to SSB modes for control purposes. See SSB
Transceive.
Advanced Operating Features
§
Once you've mastered the basics of operating the K2, you may wish to
explore some of the more specialized features and techniques
described in this section. These include:
§
§
§
§
§
§
§
scanning
reducing current drain for portable operation
using a separate receive antenna
programmable function keys (PF1/PF2)
AGC on/off control
firmware version number display
VFO frequency calibration techniques
§
Setup VFOs A and B for the two ends of the band of interest. VFO A
must be set for a frequency lower than VFO B.
Setup the desired operating mode, preamp/attenuator selection, filter
selection, tuning rate, and AGC speed (slow or fast); see scanning
tips below.
Store this setting in any memory (using the STORE switch), but
instead of tapping the switch for the desired memory (0-9), hold the
numbered switch to initiate scanning. You can also initiate scanning
when you recall a stored memory; hold RCL, then hold the numbered
switch as with STORE. This allows you to keep up to 10 of your
favorite scan ranges around for instant recall.
If the scan routine finds a station but you'd like to listen to it at a
different pitch or move past the signal manually, you can turn the
VFO knob without exiting scan mode. This is absolutely necessary
when scanning for SSB signals, since the scan routine is based on
envelope detection only and cannot auto-tune a signal.20
You can exit scan mode at any time by tapping a switch or hitting
your key or paddle.
Once scanning is initiated, the receiver will be squelched and the VFO
will start tuning up the band looking for signals. When the frequency set
up in VFO B is reached, VFO A's frequency will be re-loaded. During
20
It is possible to auto-tune to SSB signals, but the required fast audio
sampling and DSP are beyond the present capabilities of the K2.
K2 Manual 1/24/99 V.XC ©1999 Elecraft
scanning, the MHz decimal point flashes quickly. When the scanning
routine finds a signal, this decimal point is flashed more slowly. Once
a signal has disappeared, the frequency will be incremented by 300Hz
and scan resumed. (This usually prevents CW signals from locking in
a second time.)
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106
§
the scanning routine will stop scanning and "examine" each carrier for
about 1 second to see if it is varying in amplitude. The receiver will
Tips for successful scanning:
§
§
use a narrow filter if the band is even moderately noisy--otherwise
the scanning routine will stop too often on noise
use SLOW AGC if you wish to have scanning resume after a few
locked onto stations indefinitely
scan at 10Hz/step or 50Hz/step unless you're trying to cover a
very broad frequency range; if you use 1kHz/step you'll need to
post-mixer amplifier current by about 50mA and automatically
forces the bargraph to use DOT mode if set for BAR. Receiver
§
very strong in-band stations nearby.
Set GRPH to OFF; this completely disables the S-meter and forces
DOT mode for transmit power display.
Set LCD to DAY to turn off the LCD backlight. This is most
segment that is turned on in DAY mode uses about 18mA. (Each
segment uses only 6mA in NITE mode.)
each setting. All of these settings are stored in EEPROM so they will be
in effect whenever you turn the K2 on.
§
tailor the lock rate by backing down the RF gain control, even
while scanning is in progress
If you have installed the 160m/RXANT option, you'll be able to use a
separate receiving antenna. This capability is included with the 160m
If you're operating from a battery and wish to extend battery life, you
can use the menu to configure the K2 for minimum current drain.
headphones (preamp off; OPT BATT; GRPH OFF; LCD DAY).
Driving a speaker to high volume levels will increase current drain.
However, the receive antenna switch can be used on any band, and is
configured on a per-band basis. Your receive antenna must be connected
To enable the receive antenna, you must first switch to the desired band.
Next, use the menu to change the RANT option to ON. This will affect
current drain. These will have only a small effect on transmit current
drain, however. Reduce power output to the lowest effective level if
receive antennas often, you can program one of the two programmable
function buttons for RANT (see below).
§
§
§
external transmit attenuator for very low power operation (QRPp). You
can use one or two antennas. If two antennas are used, the setup is
antenna. If you wish to use a single antenna, you can use a BNC "Y"
K2 Manual 1/24/99 V.XC ©1999 Elecraft
adapter on the RCV ANT jack. Connect the antenna to one side of the
"Y," then run a small coaxial cable from the other side of the "Y" to
the transmit attenuator output. Note that this configuration will result
in a small (approx. 3dB) loss in receive signal strength due to the
extra load that the attenuator presents to the receiver.
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K2 Manual 1/24/99 V.XC ©1999 Elecraft
Programmable Function Keys (PF1/PF2)
The PF1 and PF2 switches (below RIT and XIT, respectively) can be
programmed as direct edit shortcuts to any two menu entries of your
choice. (See Edit Shortcut in the Menu section.)
To program PF1 or PF2, enter the menu and scroll to PF1 or PF2,
then change the parameter to the desired entry. To use PF1 or PF2,
simply HOLD that switch, then change the parameter (which will be
flashing) using the knob or BAND+/- switches. To return to normal
operation, TAP the PF1 or PF2 switch again.
AGC On/Off Control
Some operators prefer to turn AGC off and use manual gain control
under certain weak-signal conditions, since AGC has the effect of
"compressing" signals--that is, making all signals have relatively
constant amplitude at the audio output.
To turn off AGC, hold both the AGC and PRE/ATTN switches
simultaneously. Release the switches when you see the message
"OFF" flashed on the LCD. To remind you that AGC is off, the
decimal point to the left of the mode indicator will flash slowly.
When you turn off AGC, received signals will no longer affect the Smeter level. Turning the RF GAIN control counter-clockwise will still
cause the reading to change, however, giving you a visual
confirmation that you've reduced gain manually.
Firmware Version Number Display
You can check the K2's firmware version by holding in any switch on
power-up. Two numbers will then be displayed briefly. For example,
you might see:
"1.02 1.00"
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K2 Manual 1/24/99 V.XC ©1999 Elecraft
The first number is the main processor's firmware revision. The
second number is the I/O controller's firmware revision. Both numbers
should be reported when contacting Elecraft with questions about the
K2.
Frequency Calibration Techniques
The VFO is only as accurate as the built-in frequency counter, which
in turn is only as accurate as the 4.000 MHz oscillator on the control
board. This oscillator can be fine-tuned using C22.
C22 can be set more accurately using one of the following methods.
The first method is more direct. The second method can only be used
if you have already run CAL PLL one time, and even then it will be
somewhat less accurate. In either case, if you change C22 you’ll
have to re-run CAL PLL and CAL FIL to realize any benefit in VFO
accuracy.
§
§
The simplest way to set the 4.000 MHz oscillator frequency is to
connect both the internal counter and a known-calibrated external
counter to the same arbitrary signal. Adjust C22 until they read
the same. (This is more accurate than simply measuring the 4.000
MHz oscillator with the external counter, since nearly any
external counter probe will load down the crystal oscillator,
resulting in a reading error.)
If you have a calibrated signal source (or can receive WWV), you
can use the K2’s receiver to zero-beat a known signal to
determine how far off the VFO is, then compensate. (Use LSB or
USB since these modes don’t introduce a receive offset.) For
example, suppose you zero-beat WWV, then find that the K2 dial
is set for 10000.30 kHz. To compensate, connect the internal
counter to the VCO test point and adjust C22 until the VCO
reading is 0.30 kHz higher.
Don’t forget to re-run CAL PLL and CAL FIL after setting C22.
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110
9. Modifications
It is Elecraft's policy to encourage kit owners to experiment with their own
(careful) modifications to kits. You can build in your own accessories and
make changes to the circuitry if desired. However, this policy has one firm
limitation: If your modification damages the kit or alters normal operation, it
may not be repairable by Elecraft should you have difficulty.
All modifications should be done in such a way that they can be easily
disabled (turned off, unplugged, etc.). This will allow us to test and
repair your kit if it becomes necessary. Note that repair charges will be
higher if our technician has to un-modify your modification for any
reason.
Improving Transmitter Efficiency at Low Power Levels
The K2 is capable of 10W PEP output on 160-10 meter SSB. Of
necessity, this means that the transmitter driver and PA stages are
biased much closer to class A than they would be if the K2 were a CWonly rig. Also, a push-pull final amplifier stage is typically less efficient
than a single-ended stage. The result is that the K2 transmitter is most
efficient at 10W output, whether on CW or SSB, with efficiency
decreasing as power decreases.
If you plan to operate exclusively at or near the 5W PEP/CW level, you
can wind the driver and PA transformers differently to improve
efficiency at this level. You can remove one turn from the 3–4 winding
on T4 to immediately improve current drain by some 25 to 30% at 5
watts. A related driver transformer change was still in the experimental
phase at the time of this writing and will be posted to our web site
[TBD].
Other Suggested Modifications
§
§
§
§
§
§
The side panels are quite strong (.080 aluminum), so a carrying
handle could be added.
A transmit attenuator could be built into the top cover, with its own
BNC connectors; you could use this to experiment with QRPp
(very low power) operation.
You can install your own internal battery, rechargeable or not.
Avoid batteries that may leak or outgas when overheated.
The internal frequency counter can be used to count external
signals if you run a coaxial cable from its input to the rear panel.
Avoid routing cables near the synthesizer, crystal filters, I.F.
amplifier, or PA transistors.
The space in the top cover could be used to build a manual antenna
tuner, assuming you don't mind putting holes in the top. Several
BNC-size holes are available on the upper rear panel for connecting
antennas.
A low-level audio signal is available at J5 on the RF board (Aux.
AF). This signal could be used to drive an external audio
filter/amplifier, RTTY terminal unit, etc. You'll need to supply your
own connector to get at this signal (3 pin, 0.1" spacing). At present
the holes in the upper rear panel are not covered (unless you put in
some accessories). Field Testers are invited to help us come up with
an economical way to cover the holes.
111
10. Theory of Operation
Before reading this section you should become familiar with the schematics
System Overview
The K2’s modular design allows flexibility in configuration and provides for
accommodated in the future. The front panel and its PC board can easily be
unplugged from the front of the unit by removing just four screws, and is
The block diagram (Appendix C) shows overall signal flow in the K2.
Transmit and receive paths are shown for sideband operation. For CW
circuit boards:
Front Panel
Control Board
MCU, DC control, AGC, and AF amplifier
All RF circuitry, relays, and I/O controller (IOC)
The K2 receiver is a single-conversion superhet, utilizing double-tuned
band-pass filters on each band and down-conversion to a low I.F (4.915
This functional division allows related circuits to be grouped together, but
low I.F. is compatible with narrow, variable-bandwidth CW crystal filtering
and allows the use of fast I.F.-derived AGC. An I.F. of 4.915 MHz also
sections of the transceiver. The RF board serves as a “mother board,” while
the front panel and control boards plug into the RF board at its front edge.
controlled to allow upper and lower sideband reception on any band, as well
as CW on either sideband. AM signals can be received in SSB modes thanks
ground-plane layers forming a partial enclosure that helps minimize radiated
digital noise.
improved intermodul transmit is not currently supported.
ation performance when compared to up-conversion designs that use only a
with a unique 2-D fastener used at each joint and also for PCB support. This
design provides a rugged but light-weight enclosure that is ideal for field or
The top cover, which includes the upper portion of the rear panel, can
support a variety of built-in options such as an internal battery, automatic
with a 100W power amplifier module, converting the K2 into a mediumpower station.
conversion also requires the use of a second I.F. to obtain good CW
performance, increasing cost and producing additional spurious signals. (An
filter. While this results in minimal parts count, it was not considered since
the resulting CW and AGC performance would have been poor.)
to generate an output at the operating frequency, which is filtered by the
band-pass and low-pass filters. A highly stable power amplifier chain
K2 Manual 1/24/99 V.XC ©1999 Elecraft
provides 10 watts output or more on all bands, and the output level can be set
accurately in 0.2W increments. The transmit strip is conservatively rated to
provide excellent reliability and immunity to high SWR. The same push-pull
final amp design could be pushed to over 40W on the lower bands. Highisolation PIN-diode T-R switching is used to provide silent, no-relays QSK.
(Please refer to the RF Board section for further details.)
Coverage of 160-10 meters is provided by a single wide-range VCO
(voltage-controlled oscillator). High-side and low-side injection are both
used, depending on the band, so the overall VCO range is limited to about 6
to 24 MHz. Only one VCO is needed, with a single high-Q inductor and
three small DPDT relays configured to select one or more fixed capacitors.
The VCO is driven by a PLL synthesizer. 5 kHz frequency steps are used at
the PLL, while 10Hz increments are provided by a 12-bit DAC driving an 11
MHz VCXO (PLL reference oscillator).
Microcontroller (MCU)
The K2’s microprocessor is an integral part of all transceiver operations.
Firmware is used to advantage to provide many functions traditionally
provided by discrete control logic. For example, the VCXO (PLL reference
oscillator) is linearized on each band by a firmware auto-calibration routine,
with resulting tables stored in EEPROM. Another example is firmware ALC,
which is used on CW to maintain the user-specified power level across all
bands. The SSB adapter, when installed, provides its own optimized
hardware ALC.
Extensive use of firmware also results in many useful operating features not
usually found on transceivers in this price class. These features include builtin test equipment (frequency counter and digital voltmeter), auto-calibration,
dual VFOs, memories, split operation, RIT/XIT, and a versatile keyer.
Provisions have also been made in firmware to support a wide range of
option modules. (See full feature list elsewhere on the web site.)
Latching Relays
Latching relays are used for all filter, VCO, and option switching, so there is
no relay current drawn during normal operation. This, combined with
careful power control at all stages in the transceiver, results in receive-mode
current drain as low as 100mA. The latching relays are all controlled by a
112
single device, the I/O Controller (see below), which also handles other
miscellaneous I/O tasks on the RF board. DPDT relays are used for all filter
switching, reducing the number of relays needed by a factor of two. 50-ohm
switching is used for all filters, and this combined with careful layout and
guard-banding of the relays results in excellent filter input/output isolation.
113
Co-Processors and the AuxBus
switching is handled by co-processors. There is only one co-processor in the
basic K2, the I/O Controller (IOC). Some option modules, such as the SSB
allows future modifications to be made to option boards without changing
the transceiver itself. It also reduces cost of the basic K2, since fewer main-
The IOC, as well as all co-processors on option modules, go into “sleep”
mode with their own 4 MHz clocks suspended during normal operation. For
receiver EMI.
When the operator performs an operation that changes relay states, the main
them a configuration command. These commands are transmitted on a onewire network called the AuxBus. The AuxBus network line sits at a logic
receiver is muted during commands, so the operator never hears any digital
noise due to AuxBus activity.
be turned off when ambient lighting is sufficient (“DAY” mode) because the
LCD is transflective, i.e. it can either reflect or transmit light. The LCD
annunciators which indicate the settings of various controls.
A 10-segment LED bargraph, DS2, is used to display received and
select OFF, DOT or BAR mode for the bargraph, with OFF or DOT modes
typically used to save current during battery operation. U3 and U4 are 8things. Q1 and Q2 form a brightness control. When the NIGHT(low) control
line is pulled to ground by U3, the bargraph supply voltage drops to 2.7V,
case. When NIGHT(low) is left high for daytime use, each LED draws about
18mA, and the LCD backlight is OFF.
tuning steps of 10, 50, or 1000 Hz per increment are used, resulting in 1, 5
and 100 kHz per turn, respectively. The encoder is also used to modify
under certain operating conditions.
S1-S16 are pushbutton switches. Switch data is read by U2, an 8-bit parallel-
change. However, the AuxBus may also be used during transmit to relay
numeric data such as SWR or ALC from a coprocessor to the main
transmitted signal.
Front Panel
into the RF board via a 20-pin single-row connector, P1. The Front Panel is
made up of a number of user-interface elements as detailed below.
corresponds to a TAP (short press) and the bottom label corresponds to a
HOLD (long press, ~0.5s). Switch combinations are also supported, although
frequency entry mode, and AGC with PRE/ATTN turns AGC on or off).
Potentiometers R1, R2 and R5 (Keyer Speed, Power Out, and RIT/XIT
“VPOTS” line, so their position can be read. Firmware hysteresis is used for
these controls to prevent noise from interfering with the readings, with more
leads go directly to the input of the AF amp on the Control Board. (The
entire path from product detector to AF amp is balanced to prevent common-
backplanes (triplexed). Its driver, U1, receives display commands via an I2
interface. The LCD backlight LEDs, D2 and D3, are used to provide enough
brightness to handle low-lighting situations (“NITE” mode in the menu),
modern transceivers, the RF Gain control actually controls the receiver’s IF
gain; it varies the DC control voltage on pin 5 of U12 (RF Board).
K2 Manual 1/24/99 V.XC ©1999 Elecraft
The circuitry associated with J2, the mic jack, is only present if the SSB
option is installed. P1 is a configuration header that the user can wire as
needed to support any of several industry-standard microphones with an 8pin circular connector. Q3 and its associated resistors are used to multiplex
the UP, DOWN, and FUNCTION lines from P1 onto the VPOTS line to
allow the mic to send commands to the MCU. The PTT line from the MIC
activates the DOT-PTT line to initiate transmit. The MICAF line, mic audio
output, is amplified and processed by circuitry on the SSB adapter (see
Option Modules).
Control Board
The control board plugs into the RF board via connectors P1, P2, and P3
(along the bottom edge of the schematic). P1 handles for AGC signals while
P2 provide miscellaneous I/O. Redundant connections are provided for
ground, supply voltages, low-impedance signals (such as audio output) and a
few other critical signals.
U6 is a PIC16C77 microcontroller (MCU), with 8K of EPROM, 300+ bytes
RAM, serial I/O, parallel I/O, and A-to-D inputs. It is self-contained with
the exception of its 4MHz crystal oscillator, X2. Even when running at
4MHz, the PIC processor is very efficient: it only draws a few milliamps at
5V. Also, since the program and data memories are located on-chip, there is
very little noise radiation from the MCU.
To get the most out of the available I/O on the MCU, much of the
communication from MCU to the rest of the K2 is done via serial interfaces:
§
§
§
§
§
RS232: Used for communicating with a host computer via P4 (Aux I/O)
I2C: Display driver data
SPI: The serial peripheral interface is used to access various
peripherals, including the PLL and DACs.
AuxBus: 1-wire data network for co-processor control
Shift register I/O: serial-to-parallel shift registers are used to access
MOSFET LED drivers on the front panel; a parallel-to-serial shift
register on the front panel is used for reading pushbuttons.
114
In addition to the microcontroller the control board provides a number of
specialized hardware interfaces. Circuitry is described moving from left to
right, top to bottom on the schematic.
U10A and associated circuitry are used to accurately control power output as
well as provide CW waveform shaping.
Q9 and Q10 form a two-stage amplifier, supplying a square wave signal to
the MCU when the frequency counter is enabled and a probe is connected to
P6. The counter amp is turned off at all times except when one of the
calibration routines is being used.
The four outputs from the quad DAC (U8) provide: audio tones (via U10B),
BFO frequency control (U10D), and crystal filter bandwidth control (U10C).
Audio tone pitch, amplitude, and wave shape are controlled in firmware to
yield clean sidetone from 400-800 Hz, as well as general-purpose tones. The
bandwidth control line doubles as the transmitter driver bias control on
transmit.
Note: The sidetone signal is actually generated at pin 25 of the
microprocessor, while sidetone volume is set by the DAC using Q5 as a
variable-drain-voltage saturated switch. The DAC cannot be used to generate
sidetone directly because the 60dB channel-to-channel isolation is not
adequate to prevent slight modulation of the VBFO and BVIAS lines on
transmit.
U7 provides 2K bytes of non-volatile configuration data storage. This
memory is used for VCO lookup tables, CW messages, frequency memories
and other variables that must be permanently saved. The EEPROM can be
written millions of times without loss of data. During normal operation on a
single frequency (such as when in a QSO), the EEPROM is not accessed at
all. However, whenever the VFO is moved, a 30-second timer is triggered.
Once the VFO has stopped moving for 30 seconds, the EEPROM is updated
with the latest VFO frequency. In this way, the K2 always saves the most
recent “important” frequency. (The EEPROM update also takes place any
time you change bands or operating modes, etc., so you don’t have to wait
for 30 seconds to record an important configuration change.) An alternative
strategy used by many rigs is to use battery-backed-up RAM, continuously
recording the operating frequency. However, we preferred to eliminate the
K2 Manual 1/24/99 V.XC ©1999 Elecraft
backup battery, which often has a high failure rate and must be periodically
replaced.
The control board provides a built-in voltmeter and ammeter: Using S1, the
operator can monitor either the internal 12V supply voltage or the voltage
from a test probe plugged into P5. U3B buffers the DC signal from the probe,
and also is used in conjunction with Q11 to provide supply current
monitoring. The current sense resistor, which has a value of 50 milliohms, is
located on the RF board (R115).
U4 is a low-dropout 8V regulator, which is stable with a K2 input DC
voltage as low as 8.2V. Since all signal-generating and signal monitoring
stages in the K2 run from this 8V supply, the transceiver will function
normally even when running from very depleted batteries; most transceivers
use a higher regulated voltage for these stages and in some cases will not
operate reliably even at a battery voltage of 11V. (Transmit power will be
scaled back and a warning message displayed if the battery voltage drops
below a critical value or if current drain is excessive.) U5 provides 5V for
logic circuits on the front panel and control board, but this signal does not
appear on the RF board, so noise is minimized.
8V Switching: Q1 and Q2 provide stable +8V sources on transmit (8T) and
receive (8R). (Also note that Q23 on the RF board is used to guarantee that
8R goes to 0V on receive to maintain proper reverse voltage on T-R switch
diodes.)
An optional audio filter module can be mounted on the bottom of the control
board. This filter will provide analog and/or digital signal processing
functions. The audio filter module has its own co-processor so that it can be
enhanced in the future.
Q6 and Q7 disconnect the AF amplifier from the product detector on
transmit, which is necessary for clean QSK. U9 is an LM380 audio amp IC,
supplying approximately 1W of audio drive to a 4-ohm speaker in the cover
of the K2. Sidetone is injected post-volume control so that sidetone and
receiver audio volume can be controlled independently.
The AGC circuit is the only RF stage located on the control board.
Mixer/oscillator U1 generates a low-level signal at about 5.068MHz, then
mixes it with the 4.915Mhz I.F. signal from the RF board to produce a new
115
auxiliary I.F. of about 150 kHz. This auxiliary I.F. signal is then amplified
by U2B and detected by D1 to create a positive-going AGC voltage, which is
then routed back to the RF board to control the I.F. amp (U12). While it is
possible to generate the same AGC voltage by simply amplifying and
detecting the 4.915 MHz signal itself, this technique often necessitates
shielding of the AGC RF amplifier stages to prevent radiation of the I.F. or
BFO signals back into the receiver I.F. strip. We obtain all of the gain at 150
kHz instead, so the 4.915 MHz signal is not re-radiated. 150 kHz is high
enough to obtain fast AGC response—two orders of magnitude faster than is
possible when audio-derived AGC is employed.
K2 Manual 1/24/99 V.XC ©1999 Elecraft
RF Board
The RF board is the largest of the three K2 boards, and serves as a structural
element that the chassis and the other boards attach to. This board contains
all of the RF circuits (amplifiers, oscillators, filters, etc.). Refer to the RF
board schematic (Appendix B).
Sheet 1: Synthesizer
The K2 uses a PLL (phase-locked-loop) synthesizer IC (U4) in conjunction
with a wide-range, band-switched VCO (Q18). The synthesizer provides
approximately +7dBm output from 6 to 24 MHz, which is then injected at
the transmit and receive mixers (sheet 2). Phase noise performance of the
synthesizer is very good despite its low parts count and absence of shielding.
U4 provides coarse tuning (5 kHz steps). Fine steps are achieved using a 12bit DAC (U5) to tune a voltage-controlled crystal oscillator (Q19), which is
the PLL reference oscillator. The reference oscillator range needed on each
band varies in proportion to the VCO output frequency. To cover exactly 5
kHz in 10 Hz steps on each band, an automatic calibration routine is
provided in firmware. The DAC is swept from its highest output voltage
down, and the DAC word needed to select each 100 Hz step is recorded in
EEPROM on a per-band basis. 10 Hz steps are then interpolated based on
the 100 Hz table data. Crystals X1 and X2 in the PLL reference oscillator
have carefully controlled characteristics. They de-Q each other to increase
the tuning range of the VCXO to about 10-12 kHz, which is required in
order to tune the full 5 kHz on the lowest band (160m), but still provides
better than 10 Hz resolution on the highest bands.
The synthesizer design is unique in that three inexpensive DPDT latching
relays are used to select one of eight VCO ranges, thus requiring only a
single high-Q VCO inductor (T5). The relays are optimally interconnected to
allow for maximum coverage of the nine HF bands, plus a large out-of-band
tuning range. Computer simulation was used to find a relay topology that
allowed for the use of standard 5% fixed capacitors along with the smallest
practical varactor diode capacitance. As a result, the VCO exhibits low noise
on all bands and has a low max/min tuning ratio on each band.
116
In order to provide some allowance for unit-to-unit variance in T5, a much
higher value slug-tuned inductor (L30) is placed across T5’s high-impedance
winding. L30 has only a small effect on the Q of T5, but provides about a
20% tuning range. The combined parallel inductance is very small (only
1uH), resulting in a very large C/L ratio on the lowest bands.
U3 buffers the VCO signal. Q16/Q17 provide stable ALC to keep the VCO
voltage fairly constant over the entire frequency range despite variations in
the VCO transistor, Q18.
(Next revision: include VCO tuning range table [TBD])
Sheet 2: Receiver and Low-Level Transmitter Circuits
The receiver is a single-conversion superhet with an I.F. (intermediate
frequency) of 4.915 MHz. The preamp and attenuator are switched in using
latching relays so that no current is required except when switching them on
or off. The mixer is a diode ring type, providing good dynamic range (Z6),
and is followed by a strong post-mixer amplifier, Q22. The current drain in
Q22 can be reduced by the operator using a menu option that turns off Q12.
A 5-pole variable-bandwidth crystal filter is used on CW (X7-X11). This
filter is optimized for use at low bandwidths (~200 to 500 Hz), but can be set
both narrower and wider as needed with only a small additional loss. The
shape factor and passband ripple content are optimized at around 300 Hz.
(On SSB, a separate fixed filter is switched in; this filter is located on the
SSB adapter.)
AGC is derived from the output of the I.F. amp by using an auxiliary, lowfrequency I.F. of about 150 kHz (see Control Board). The AGC signal is then
applied to pin 5 of the I.F. amp (U12).
A second crystal filter (X6/X5) follows the I.F. amp. This filter is also
tunable, but over a smaller bandwidth range. Varactor diode D39’s
capacitance is increased during CW use, but on SSB is quite broad. The
product detector is a Gilbert-cell mixer/oscillator (U11). Due to the loss in
the second crystal filter, the input voltage to U11 never exceeds the range
that the device can handle.
K2 Manual 1/24/99 V.XC ©1999 Elecraft
U11 also provides the BFO signal, which is tunable over about a 4 to 5kHz
range by varactor diodes D37 and D38. X3 and X4 have carefully-controlled
characteristics and are well matched. As in the PLL VCXO (Q19, sheet 1),
the two crystals de-Q each other to increase the tuning range of the BFO.
On transmit, BFO buffer/attenuator is turned on. Q24’s drain voltage is
controlled by the microprocessor, providing BFO amplitude control. PIN
diode D36 provides additional reduction in low-level signal leakage when
Q24 is turned off. U10 mixes the VCO with the BFO on transmit, and video
amplifier U9 increases the signal level while providing a low-impedance
output to drive the bandpass filters (sheet 3).
Sheet 3: Filters and I/O Controller
The band-pass and low-pass filters are switched with latching relays to
minimize loss and current drain. Only five band-pass filters and seven
DPDT relays are required to cover nine bands (160-10m). This is
accomplished by switching fixed capacitors in or out using two additional
relays. For example, on 160 meters, relay K3 places C13 and C14 into the
80m band-pass filter. But relay K3 also used to switch the 30meter band-pass
filter to 20 meters by shorting C21 and C23 to ground. A similar technique
is used for the 10/12 and 15/17 meter filters. The band-pass response is a
compromise on 80 and 160 meters but on all other bands is similar to what
would be obtained with separate filters.
The low-pass filters also serve double-duty in most cases; five filters cover 8
bands (80-10m). The 30/20m filter uses three pi-sections to provide good
roll-off of the 20 MHz second harmonic when operating on 30 meters. Most
of the filters are elliptic, aiding attenuation of specific harmonics. But
elliptic filters are not needed on 40 and 80 meters since these each cover
only one band. The 2nd harmonic attenuation provided by the push-pull
power amplifier is quite good even pre-filter (sheet 4).
DPDT relays are used for the low-pass and band-pass filters rather than the
traditional SPDT approach which requires twice as many relays. This is
possible by virtue of careful guard-banding techniques on both top and
bottom of the PC board in the filter areas. Isolation between input and output
of each filter is excellent across the entire frequency range.
117
The T-R switch (D1-D5) provides very high isolation using low-cost silicon
diodes with a PIN characteristic (1N4007). Q2 is a very high-voltage
MOSFET that provides a ground path on receive for D3 and D4, but on
transmit this transistor can easily handle the high voltages present on the
power amplifier collectors.
U1, a low-cost 28-pin PIC microprocessor (16C72), drives all of the latching
relays and a few other I/O lines. U1 is referred to it as the I/O controller
(IOC) because it handles nearly all I/O functions for the main processor. It
also has the job of determining whether the 160m/RXANT option board is
installed by sensing the presence or absence of the two relays on the module.
Finally, the IOC contains all of the per-band and per-memory initialization
data in ROM, which is sent to the main processor as needed to initialize
EEPROM data tables. A number of different regional band plans and other
customized parameters can be accommodated in U1’s data tables.
The latching relays are wired with a single common drive line so that when
one relay needs to be turned on or off, the others are pulled in the opposite
direction. This arrangement requires no drivers of any kind. U1’s I/O lines
are protected from relay transients by its own internal shottky clamping
diodes to 6V and ground. Measured transients are well within the current
rating of the clamping diodes. Transients are reduced in amplitude by the
series resistance of the other non-switched relays and U1’s own MOSFET
driver impedance. The relays are rated at 5V nominal (250ohm coils). The
actual impressed voltage is in the 5V to 6V range, depending on ambient
temperature, reflecting the best and worst-case sink/source current limits of
the 16C72.
The IOC communicates with the main processor over the 1-wire AuxBus.
U1’s 4 MHz clock is turned off and the device is in sleep mode at all times,
except when it is processing an AuxBus message, so there is no digital noise
on receive. Note that the main processor runs from a 5V supply while the
IOC runs from 6V. The AuxBus is designed to accommodate devices
running at both voltage levels.
Sheet 4: Transmitter Amplifier
Q5 and Q6 are class-A pre-driver and driver stages, respectively. Q5’s bias is
provided directly by the 8V transmit line (8T), while Q6’s bias is switched
on by the 8T line but is gated by Q10. This is necessary because the DAC
K2 Manual 1/24/99 V.XC ©1999 Elecraft
output that supplies the bias voltage for the driver is used as the crystal filter
bandwidth control voltage on receive. The bias to Q6 can be varied under
firmware control to optimize efficiency for CW vs. SSB and at different
output levels. This is useful in maintaining high overall efficiency during
battery operation.
Q7 and Q8 form a conservatively-rated push-pull power amplifier that can
easily supply 10 watts output on all bands. Q11 and Q13 are used as a bias
voltage regulator. The bias regulator is effectively out of the circuit on CW
because of the large size of resistor R62, resulting in approximately a class-B
bias level. On SSB, resistor R63 is grounded by the I/O controller, causing
much more current flow through Q13 and stabilizing the bias for class AB
operation. R60 is adjusted for the desired class AB standing current using
voltage/current monitor mode on the LCD.
118
K2 Manual 1/24/99 V.XC ©1999 Elecraft
11.
This section provides detailed troubleshooting tables that will help you find
and correct problems with the K2. There are five tables (listed below).
Your troubleshooting experience may be helpful to future K2 builders. Feel
free to contact us to report the problem and how you solved it (e-mail
shown. In most cases you’ll know which table to look in based on the
symptoms you observe. If in doubt, start with the General Troubleshooting
Table Conventions: When referring to components on the various K2
“RF/U11,” which means U11 on the RF board.
General Troubleshooting
Receiver
Transmitter
000-049
050-099
NOTE: This table will be expanded when the manual is next revised.
150-199
200-249
INFO Messages:
conditions. If this happens you’ll see a message such as “INFO 100” on the
LCD. The 3-digit number in the INFO message tells you which
Note: INFO messages can be cleared by pressing any switch. However, the
cause of these messages should be investigated before continuing to operate
Problem
Unit appears to
be completely dead
Troubleshooting Steps
Make sure your power supply or battery is
§
turned on (no display,
no audio)
§
§
Troubleshooting Tips: When you locate your problem in the table, follow
§
If you have a problem that isn’t addressed specifically, you can often locate
the cause using a combination of signal tracing, DC voltage and resistance
important to keep in mind that actual component failures are fairly rare. In
most cases you’ll find that a broken interface cable, cold solder joint,
005 No display, but
applicable
Examine power cable for shorts or opens
Verify control board is plugged in and that
its connectors are fully seated
Check for 12VDC at the power jack
Make sure speaker, battery, and other
backwards
Measure the +5V and +8V regulated power
supplies. If either is incorrect, check the
§
§
front panel connector is properly mated with
the RF board
K2 Manual 1/24/99 V.XC ©1999 Elecraft
§
010 Battery voltage
too low for proper
voltage regulation
§
§
If the front panel is plugged in correctly but
the problem still persists, check all LCD
voltages and control lines (060)
If you saw INFO 010 on the LCD, your
battery voltage is too low (< 8.5V). This
usually happens on transmit when your
battery is weak. Disconnect the battery from
the K2 and measure its voltage; if the battery
voltage quickly rises back to 11 or 12V, the
K2 may be loading the battery down. But if
the battery stays stabilizes at under about
10V when measured outside of the K2, it has
become fully discharged or may be defective.
If you suspect the K2 is pulling the voltage
down, tap any button to clear the INFO
message then use DISPLAY to show the
voltage and current drain. If the current
drain is > 200mA with no signal and the
bargraph OFF, something is shorting either
the 12V line or one of the regulators (050).
Make sure that a working antenna is
connected; check antenna switch, tuner,
SWR bridge, etc.
See Receiver Troubleshooting (100)
Front panel or control board may not be
plugged in correctly
Check the MCU (075)
Check all regulated supply voltages (050)
§
Check receive-mode current drain (140)
§
Connect the K2 to a known 50 ohm load
(preferably a dummy load); if current drain
returns to normal, you probably have a
mismatched antenna and will have to
improve the match or reduce output power
If you have set the power level control
significantly above the level that the
transmitter is capable of, current may
increase significantly; try reducing the power
§
§
011 No audio, but
display is OK
012 Display, VFO
knob, switches, or
potentiometers do not
function correctly or
are intermittent
015 Current drain
excessive on receive
016 Current drain
excessive on transmit
§
§
§
§
120
§
§
018 Supply voltage
drops when K2 is
turned on
§
§
019 Supply voltage
drops too low when
transmitter is keyed
§
§
025 Battery won’t
charge up to the
correct voltage, or
discharges too quickly
§
§
§
030 VFO frequency
“jumps” or drifts, or
operating frequency
§
setting
Use voltage/current monitor mode to see if
the power supply voltage drops below 11V
on transmit; if so, you may be exceeding the
capability of your power supply or battery
(025)
If the power supply voltage and antenna
impedance are correct, the driver or PA
transistors may not be operating efficiently
(150)
Use voltage/current monitor mode to see if
the receive-mode current drain is too high
(015)
If voltage drops but current drain is normal,
you probably have a power supply problem
or a battery that is not fully charged (025);
review power supply requirements
(Specifications)
Use voltage/current monitor mode to see if
transmit-mode current drain is too high
(016)
If voltage drops but current drain on transmit
is normal, you probably have a weak battery
or inadequate power supply (025)
Batteries must be charged using the right
voltage or their usable life will be greatly
reduced; if you have the K2 internal battery
option, refer to the charging instructions in
the option manual
Battery life can be extended by reducing
power output and by turning off selected
features using the menu; see Operation
Always disable the K2’s internal battery
using the rear-panel battery on-off switch if
you plan to use an external battery OR
reduced-voltage power supply that is
inadequate for charging purposes
You must align both the VFO and BFO
using the CAL PLL and CAL FIL before
operating the K2; otherwise the VFO cannot
121
Remove the microprocessor to see if it is
appears to be incorrect
not be locked (see Operation as well as RF
board Alignment and Test, Part II)
Make sure the supply voltage is above 8.5V
§
function correctly.
If you used CAL FIL to change the BFO
settings, make sure you placed the BFO on
§
if the voltage is still too low, replace the
regulator.
Trace and inspect the entire 8V path on the
+8V too low (<
7.5V)
§
each operating mode (see Operation, Filter
Settings)
If you tune beyond the lock range of the
§
easily break the 8V line to eliminate parts of
the circuit in your search for the problem.
may “hunt” near the end of this range. If you
are in a range that the VCO should be
§
components or shorts.
Unsolder the output pin of the 8V regulator
and measure its voltage to see if the
you lift one end of this inductor it will
disconnect the entire synthesizer from the
(see RF board Alignment and Test, Part II)
For VFO and BFO troubleshooting, see
Control Circuits (TBD)
§
with the 8V line, for example R112 in series
with the I.F. amplifier (U12). If you measure
Problem
Regulated
voltage(s) incorrect
may find a circuit that is drawing high
current or is shorted. Example: If you
Troubleshooting Steps
Remove all option boards, since any one of
§
§
§
+5V too low (<
4.5V)
§
the other, it would indicate that U12 had a
current drain of 180mA, which is much too
regulated supply line
Make sure that the DC input voltage at J3 is
> 8.5 (the minimum voltage needed by the
052
If +8V is too low (< 7.5V) go to 053
Remove the front panel to see if it is was
060
LCD
§
§
is likely to be on the control board.
Pull the control board out and inspect the
entire 5V line looking for heat-damaged
used to identify all components on the 5V
line.
chart)
If the bar-graph is also not working, check
the 5V regulator (
)
Remove the front panel hardware and panel
from the front panel PC board and inspect
components. You may have LCD driver U1
in backwards or it may have a bent pin.
Check the values of R15 and R16 on the
§
voltage for the LCD itself.
Re-install the front panel board and turn on
K2 Manual 1/24/99 V.XC ©1999 Elecraft
075 Possible MCU
problem
§
§
§
080 Possible IOC
Problem
§
§
§
§
§
the K2. Using a voltmeter, measure the
voltages on pins 16 and 17 of front panel
connector J1 (ICLK and IDAT). These lines
should show DC voltages between 0 and 5V
due to data transmission from the
microprocessor to the LCD driver. If the
voltages are fixed at either 0V or 5V rather
than being somewhere in-between, the MCU
may not be functioning (075)
Measure the voltage on pin 31 of the MCU
(U6, control board). If it is not 5V, check the
5V regulator (052).
Remove the control board and carefully
inspect the microprocessor. Make sure it is
not installed backwards, has no bent pins,
and is seated firmly in its socket.
Verify that the MCU oscillator components
all have the correct values and are soldered
properly, with no shorts (X2, C21, C22).
If you saw the message INFO 080, the I/O
controller (IOC, RF/U1) did not respond to
messages from the main processor (MCU).
Turn power OFF and back ON; if you hear
some relays switching on power-up, the IOC
may be OK, and the problem is likely to be
with the AuxBus (081)
If you do not hear any relays switching on
power-up, your IOC (RF/U1) may be
defective. Inspect U1 carefully to see if you
have installed it backwards or if any pins are
bent.
Pull U1 out, check its pins, then re-install it,
making sure all pins make good contact with
the IC socket.
Remove the bottom cover and verify that all
pins of U1’s socket are soldered, as well as
those of the 6V regulator (RF/U2), and U1’s
4 MHz oscillator (RF/Z5).
With power ON, check all voltages
associated with U1. You should see 6V at
122
081 AuxBus problem
§
§
§
090 EEPROM test #1
failed
§
091 EEPROM test #2
failed
§
§
pins 1 and 20 at all times, even when the
IOC is sleeping (not being accessed by the
MCU).
Check the voltage at pin 28 of the IOC
(RF/U1). It should be between 5 and 6V. If it
is zero volts, you probably have a short
somewhere on the AuxBus line. Turn power
OFF, then measure pin 28 of U1 to ground.
If it is a short, pull the control board out to
see if the short is on that board.
If the voltage at pin 28 is between 5V and
6V, try pressing the BAND+ button a
number of times while watching the voltage
carefully (use an oscilloscope if possible).
The voltage should drop below 5V briefly if
the MCU (CTRL/U6) is sending a message
to the IOC. If the voltage does not change at
all, the MCU itself may not be sending
AuxBus messages.
Check the AuxBus signal at the MCU, pin
40 (CTRL/U6). If you don’t see this voltage
drop below 5V briefly when the band is
changed, the MCU may not be functioning
(075).
If you saw the message INFO 090 or INFO
091 on the LCD, one of the EEPROM write
tests has failed.
Check all voltages on the EEPROM
(CTRL/U7).
Remove the control board and inspect U7
and surrounding traces. Verify that U7 is
properly soldered.
Receiver (100-149)
Problem
100 No audio output
from receiver
§
Troubleshooting Steps
If you hear normal audio output on some
bands but not all of them, check the band-
K2 Manual 1/24/99 V.XC ©1999 Elecraft
§
§
§
§
§
§
§
§
§
§
110 AF amp not
working
§
pass and low-pass filters and T-R switch
(120)
Make sure you have headphones or speaker
connected and do not have the AF gain set at
minimum (counter-clockwise)
Check the key or key jack for a short to
ground
Make sure the RF gain control is not set for
minimum gain
If you have the 160m/RXANT option board
installed, you may have menu entry rANT
turned ON but no receive antenna connected
Peak the band-pass filters if you have not
already done so
Turn the AF gain to maximum (clockwise).
If you don’t hear any “hiss” at the receiver
output, troubleshoot the AF amplifier (110)
Check the 8V regulated supply voltage and
troubleshoot if necessary (053)
Measure the 8R line (+8V receive) at the
anode of D6 on the RF board. It should be
8V +/- 0.5V. If not, look for a problem in the
8V switching circuitry (control board).
Use a 3’ long piece of hookup wire to do
“signal injection,” working backwards from
the audio amplifier stage. Start by touching
the wire to pin 4 of RF/U11 (product
detector). If you don’t hear a hum when you
touch the wire to this pin, the AF amp input
may be shorted or open on the control board.
Next, touch the wire to pin 1 on RF/U11. If
you don’t hear an increase in noise, look for
a problem in the product detector circuit.
Continue tracing backwards until you find
where the signal is getting lost.
Try using signal injection if the problem is
occurring in an earlier stage of the receiver.
Use the menu to set a sidetone level of 60
(ST L 060). Press SPOT. If you hear a strong
tone, the A.F. amplifier itself is probably
123
§
120 Signal loss only
on some bands
§
§
§
§
§
140 Receiver current
drain is too high
§
§
working; check the mute circuit (CTRL/Q6
and Q7) and trace the volume control lines
back to the product detector (RF/U11)
Remove the control board and inspect the
entire A.F. amplifier and mute circuit for
mis-installed components, shorts, and opens
If you have the 160m/RXANT option
installed, make sure you have menu entry
rANT set to OFF, or if it is ON that you have
a receive antenna connected
Try peaking the band-pass filters on the
affected bands
Inspect all components in the T-R switch
area, and check all T-R switch voltages
Trace the signal from band-pass filters back
all the way to the antenna using an RF signal
generator
Make sure the VCO is oscillating on affected
bands by using the frequency counter
If you saw the message INFO 140, your
receive-mode current drain was measured at
over 400mA during normal operation.
Continue with the checks below.
Use DISPLAY to show voltage and current
on the LCD. If the current shown is >
300mA with no incoming signal or >
200mA with the bargraph turned OFF and
no signal, you may have a short or excessive
load on the 8V or 8R lines (053).
K2 Manual 1/24/99 V.XC ©1999 Elecraft
124
Transmitter (150-199)
Problem
150 General
Transmitter problem
§
§
§
§
§
155 Power output is
too low
§
§
§
§
§
§
§
160 Power output
fluctuates
§
Troubleshooting Steps
If power output is too low, go to 155
If power output slowly increases during keydown, go to 160
If current drain on transmit is too high for
the given power level, go to 175
If the transmitter output power seems to be
unstable go to 160
If the transmitter stops transmitting by itself
go to 170
Check power output when using a 50
dummy load; if the output is correct on a
dummy load but not when using an antenna,
your antenna is probably not matched
Check all component values on the top side
of the RF board
Examine transformers T1-T4 carefully; these
must be wound as indicated in part III of the
RF board assembly section (see this section
for drawings)
Check all DC voltages in the transmitter
area (TBD: voltage chart)
Make an RF probe (see any ARRL
Handbook) and signal-trace through the
transmitter to find where the signal is getting
lost
Check for any components getting too hot
during transmit
Turn the K2 OFF and remove the heat sink;
visually inspect all parts and check for shorts
or opens
If you stay in key-down (TUNE) mode for
several seconds, it is normal to see some
increase in power; this is due to slow
junction heating in the final amplifier
transistors. It is not indicative of a problem
unless current drain is too high for the given
§
§
170 Output power
drops to zero when
transmitting
§
175 Current drain too
high on transmit
§
§
§
power output.
If power goes up and down significantly
during normal keying, you may have a
poorly-matched antenna OR you may have
power set too high for your battery or power
supply to handle; try reducing power to see if
it stabilizes
If the transmitter is truly unstable
(oscillating) even when connected to a 50
load, you may have an incorrect component
value or a toroid-winding error; go through
the checks at 155
If you have transmit power set too high for
your battery or power supply, the supply
voltage may drop so low on transmit that it
resets the MCU (CTRL/U6) or the I/O
controller (RF/U1). Reduce power.
You may have power set higher than the
final amplifier can achieve, resulting in
overdrive of all transmitter stages. Try
reducing power to see if normal current
drain is observed at lower power levels
(TBD: power vs. current chart)
Use the menu to check the setting of CAL
BIAS. It should be 144 (TBD) for normal
operation. If it is too high, the driver current
may be excessive (RF/Q6). If it is too low,
the driver gain will be reduced and it may
not drive the PA transistors effectively.
Damaged PA transistors or other
components could cause inefficiency in any
stage of the transmitter. Check all DC
voltages and components, and signal trace if
necessarily (155)
K2 Manual 1/24/99 V.XC ©1999 Elecraft
Operation and Alignment (200-249)
Problem
201 EEPROM
§
not a problem indication. You will see INFO
201 one time on power-up. The only other
install a new version of the firmware that
requires a reformat of EEPROM. (In most
EEPROM reformat, however.)
INFO 230 is displayed if you try to use CAL
230
connected to frequency
counter
231
connected to frequency
counter
counter cable to the BFO test point (RF/TP2)
INFO 231 is displayed if you try to use CAL
counter cable to the VCO test point
(RF/TP1)
INFO 235 is displayed if CAL PLL cannot
PLL ref.
oscillator range error
band due to inadequate PLL reference
oscillator range (RF/Q19).
This is most likely to happen on 160m, but
§
problem with this oscillator.
Re-test the PLL reference oscillator using the
procedure described under “PLL Reference
§
Alignment and Test section.
If the PLL reference oscillator range is found
to be inadequate, check X1 and X2 for
component values in the area of Q19. Look
for unsoldered pins, incorrect capacitor
K2 Manual 1/24/99 V.XC ©1999 Elecraft
126
12. Internal Options
The K2 can be customized using a variety of internal options, which are
briefly described in this section. For more details, please refer to the
assembly and operation instructions that come with each option kit.
The options described here can only be installed inside the K2 cabinet. Most
option modules include their own dedicated microcontroller that is accessed
via the Elecraft AuxBus. This method of control allows for future expansion
without replacement of the main processor. Option microcontrollers are
turned off at all times during receive, so there's no added digital noise.
SSB Adapter: The SSB adapter allows the K2 to transmit and receive LSB
and USB on all bands. Peak envelope power (PEP) is approximately 10
watts.
This adapter includes its own crystal filter that is optimized for SSB transmit
and receive. Space is also provided for a second filter that can be custom
built by the user or purchased from Elecraft. Either filter can be a fixedbandwidth CW or RTTY filter if desired.
When the SSB adapter is installed, the user can configure the mic gain and
speech processing level using two menu entries. An on-board
microcontroller handles commands from the AuxBus as well as optimized
ALC, filter configuration, and BFO control.
Noise Blanker: The noise blanker is a very small module that fits just above
the I.F. post amp. It is effective on a wide range of noise sources, and
includes multiple programmable gain settings. The noiseblanker is
controlled using two dedicated front-panel functions, NB and LEVEL.
Automatic Antenna Tuner (ATU): The automatic antenna tuner is
extremely compact--less than 1.5 x 1.5 x 5 inches (38 x 38 x 127mm)--and
fits into the top cover between the internal battery bracket and rear panel.
The ATU itself is intended to match unbalanced lines, but an external balun
is included for versatility. The ATU includes an integral A/B antenna
switch, SWR bridge, and dual-configuration L-network to handle a wide
range of impedances. The antenna switch is controlled by the front-panel
"ANT2" button.
All relays are of the latching type, resulting in nearly zero current drain
except when an antenna is being tuned.
Note: If you install the PA (Power Amp) option, you cannot install the ATU
option.
Antenna Switch/SWR Bridge: This option is a low-cost subset of the ATU
option. It includes only the dual antenna switch and forward/reflected power
metering. (Availability for this option has not yet been determined.)
Note: If you install the PA (Power Amp) option, you cannot install the
Antenna Switch/SWR Bridge option. However, the PA may include its own
antenna switch and/or SWR bridge (to be determined).
Host Interface and Aux. I/O: The host interface adapter fits into the top
cover, and can be installed even if the battery and ATU (or PA) are present.
A DB9 connector is used to receive commands from a compatible computer
or terminal, with adjustable baud rate. A real-time-clock option is also
planned for the host interface adapter, which would allow time (UTC) to be
displayed on the K2's LCD.
In addition to the RS232 interface, the host adapter’s connector provides a
number of control lines that can be used with external equipment. These
include 8V signals for transmit and receive.
K2 Manual 1/24/99 V.XC ©1999 Elecraft
Internal 12V Battery: The internal battery is a 12V, 3A-hour gel cell that
ATU and/or host adapter is present. Recharging requires an external 13.814.0V regulated power supply.
aluminum battery bracket; gold-plated connectors; ultra-low-drop reversepolarity protection diode; and a heavy-duty 10A on/off switch that is
Note: If you install the PA (Power Amp) option, you cannot install the
Power Amp (PA): A complete description of the PA module will appear in
Note: If you have installed the ATU, Antenna Switch, or internal battery
160M/RX ANT Switch: The 160 meter module kit includes: (1) low-pass
switch (DPDT relay); (3) receive antenna jack (BNC); and (4) VCO and
band-pass filter components for 160 meters. The receive antenna switch can
operators frequently use a low-noise receiving antenna such as a Beverage.
Audio Filter:
the next revision of the manual.
Transverter Interface:
transverter (internal or external) that requires a 0dBm input signal on
transmit. (Some transverters use a higher-power input signal, and can
Six Meter Transverter: A complete description of the 6m transverter option
under consideration.
Appendix A
K2 Front Panel Board Parts List
Picture
Ref.
Bumpers; rubber,
adhesive
Value
1/4"d x 1/16"
Description
Qty
For front Panel Mounting
1
C1, C3
.047
Red Monolithic Ceramic Caps
2
C2, C4, C5, C6, C7, C8,
C9
.01
Red Monolithic Ceramic Caps; C4-C8 are for SSB
OPTION
2
D2, D3
D4, D5, D6
backlight LEDs +
diffuser
1N5817
LCD Backlights mounted in Diffuser
2
3
DS1
VIM-838-DP
7 Segment LCD Display
1
DS2
10LED array
Hi-eff. Green LED Bargraph
1
bivar spacers
for LCD LED Backlights
4
#4, lockwasher
4-40 , screw. 3/8 BLK
4-40, screw
4-40, screw; 3/16" BLK
4-40, standoff
4-40, standoff
20p female
internal tooth
machine, phillips, Pan-head 3/8" long Black
3/16”, flathead phillips, 82 deg, 0.21 dia head
machine, phillips, Pan-head 3/16" long Black
threaded hex 0.5" x 0.25" dia.
1/4 L x 3/16 D, threaded, round, Al
FP to RF Board 20 pin x 1 Socket
5
2
1
3
2
3
1
8p male
rectangular, black
Mic Jack; Male; PCB Mount
1
13
HW
Note: All 4-40 HW
is in Misc. bag. HW
HW
HW
HW
HW
HW
J1
J2
Keycap
Appendix A
K2 Front Panel Board Parts List
Picture
Ref.
Value
Description
Qty
Keycap
Keycap
rectangular, gray
square, black
Band up/down; S1, S3
Rate / Lock Key; S7
2
1
KN11
Knob, 1.6" diam
Main Tuning Knob, Black, 6mm bushings
1
KN2, KN3, KN4, KN5,
KN6
Misc
P1
Knob, 0.5"
diam
Lexan
display
panel
cover
8x2,male
Black,Bezel
Smallfor
Knobs,
6mm bushings
Clear
LCD Cover
(Screws are in Misc
Bag)
dual-row 8-pin low-profile header, SSB option
5
1
0
Q1, Q2
Q3
PN2222A
2N3906
R1, R2, R4, R5
10K POT
SSB option
Keyer Speed, Power Out, I.F. Gain, RIT/XIT Offset
Pots
R3
R10
R11
R12
R13
R14
R15
R16
R6, R7
R9
5K POT
33
470
120
68K
100K
10K
15K
4.7K
220
Audio taper Pot - Volume Control
1/4w resistor
1/4w resistor
1/4w resistor
1%, SSB option
1/4w resistor
1/4w resistor
1/4w resistor
1/4w resistor
1/4w resistor
1
1
1
1
0
1
1
1
2
1
RP1
RP2
100K SIP; 10A1-104G
120 SIP; 770101121
SIP Resistor pack, 10pin, 9r, Yellow
SIP Resistor pack, 10pin , 9r, Blue
1
1
2
0
4
Appendix A
K2 Front Panel Board Parts List
Picture
Ref.
Description
SIP Resistor Pack 8pin , 4r, ISO; SSB option
Qty
0
S1, S2, S3, S4, S5, S6,
S7, S8, S9, S10, S11,
S12, S13, S14, S15, S16 switch, push button
Socket
40 pin DIP socket
Front Panel push button switches
For LCD driver
16
1
U1
U2
PCF8566PN
74HC165N
LCD Driver, 40 Pin
8-bit PISO SR
1
1
U3, U4
TPIC6B595N
8-bit SIPO SR w/DMOS fet O.D. outputs
2
RP3
In Misc. Bag
Value
10K SIP
Washer, Felt
Z1
1" x 1/16" Felt Washer for Main Tuning Dial
Shaft Encoder
Shaft Encoder; straight pins
1
Appendix A
Picture
K2 Control Board Parts List
Designators
Value
Description
QTY
C22
C1, C33
var,8-50pF
2.2µF
Ceramic trimmer
Electrolytic
1
2
C10, C11 C17, C18, C23, C3,
C35, C37, C39, C40, C41, C5, C9
C13, C32
C14, C16, C19, C30, C6
C15
C2, C12, C20, C34
C21
C24, C36
C25, C26,C31
C27
C28, C29
C38
C4
C7
C8
D1, D2
D3
.01
22µF
.047
100µF
.001
33
.0027
0.1
.022
220µF
680
0.47uF
330
39
1N4148
1N5817
Red Monolithic Ceramic Caps
Electrolytic
Red Monolithic Ceramic Caps
Electrolytic
Red Monolithic Ceramic Caps
NPO Ceramic
13
2
5
1
4
1
2
2
1
2
1
1
1
1
2
1
4-40,screw
#4,lockwasher
4-40,nut
5p Female
3/8". Pan-head phillips, Black
Lockwasher, Internal Tooth
Note: All 4-40
HW is in Misc.
bag.
HW
HW
HW
J1
Red Monolithic Ceramic Caps
Electrolytic
NPO
Monolithic
NPO
NPO Ceramic
Audio Filter OPTION
4
2
2
0
Appendix A
Picture
K2 Control Board Parts List
Designators
J2
Value
3p Female
Description
Audio Filter OPTION
QTY
0
Appendix A
Picture
K2 Control Board Parts List
Designators
P1
Value
6P male
P2
18x2 male
P3
P4
P5, P6
R1
R10
R16
R17
R18, R19
R2
R20
R21
R3, R5
R6
R7
R8
R9
RP1
RP2, RP4
RP3
RP5
RP6
RP7
10x2 male
5x2 male
2p male
100K
196K
10
10M
1.5K
3.3M
2.7 ohm
10K
33K
470
1.96k
100
806K
S1
Description
To RF Board, J6
QTY
1
1
33K SIP; 8A3-333G
1%
1%
1%
SIP; ,5R ISO, 10 pins, Blue
SIP; 4R ISO, 8 pins, Blue
SIP; 5R ISO, 10 pins, Yellow
SIP; 5R ISO, 10 pins, Yellow
Sip ; 5R ISO, 10 pins, Yellow
SIP; 4R ISO, 8 pins , Yellow
1
1
2
1
1
1
1
2
1
1
1
2
1
1
1
1
1
2
1
1
1
1
SPDT
Slide Switch; voltage probe
1
3.9K SIP; 770103392
82K SIP; 77083823
47K SIP; 10A3-473G
470 SIP; 10A3-471G
10K SIP; 10A3-103G
0.1 centers.
Volt Meter, Freq. Counter Inputs
1%
Appendix A
Picture
K2 Control Board Parts List
Designators
Socket
U1
U2
U3
Value
40 pin socket
SA602AN
LM833N
LMC6482AIN
Description
Socket for Pic16C77 uP
AGC Mixer
U4
LM2930T-8
8V Regulator, TO-220 package
1
U5
78M05
5V Regulator; TO-220 package
1
U6
U7
U8
U9
U10
Q1, Q2
Q3, Q4, Q5
Q6, Q7
Q8, Q11, Q12
Q9,Q10
X1
X2
PIC16C77-04/SP
25LC160
MAX534
LM380N-8
LMC660
2N3906
2N7000
J310
PN2222A
MPS5179
5.068Mhz
4.000MHz
MCU, Programmed
EEPROM
Quad, 8-bit DAC
Audio Amplifier
1
1
1
1
1
2
3
2
3
2
1
1
Frequency Probe Amplifier
low-profile crystal for IF AGC Mixer
low-profile crystal for PIC uP
QTY
1
1
1
1
Appendix A
Picture
K2 RF Board Parts List
Designators
Value
Description
QTY
C1, C2, C9, C17, C26, C27, C37, C38,
C39, C49, C57, C64, C77, C79, C80,
C81, C82, C89, C100, C140, C167,
C195, C204, C207, C208, C216, C223
C103
C104, C214
C105, C106, C111
C11, C16, C191
C12, C15
.001
220uF
68
2.2uF
1800
560
Red Monolithic Ceramic Caps
Electrolytic
NPO 100v
Electrolytic
NPO, 80/160m BPF
NPO, 80/160m BPF
C125
22uF
Electrolytic
1
C126
47uF
Electrolytic
1
C127, C128
680
NPO
2
C13, C14,C190, C192
C144, C5, C7, C197, C222
C153, C221
C169
C180
C182
C19, C25, C30, C36, C150
1200
100
39
390
22
180
330
NPO, 80M BPF, C190, C192 160m
OPTION
NPO; TX injection, 40m BPF
NPO
NPO
NPO
NPO
NPO, TX Vid Amp Shaping, 15/17m BPF
2
5
2
1
1
1
5
27
1
2
3
2
2
Appendix A
Picture
K2 RF Board Parts List
Designators
Value
Description
QTY
C198
27
NPO 100v
1
C20, C24, C73, C203
C200, C212, C218
47
150
NPO
NPO 100v
4
3
C21, C23
C219
C22
C31, C35, C122
C33
C4, C8, C226
C42, C48, C173,C199, C201, C220
C43, C47,C116, C213
var,8-50pF
12
3pf
56
3pf
820
220
33
ceramic trimmer; RED Ink on side
NPO 100v
NPO, 20/30m BPF
NPO, 15/17m BPF
NPO
NPO, 40m BPF
NPO, 10/12m BPF
NPO
2
1
1
3
1
3
6
4
C44, C46, C32, C34
C45
var,5-30pF
2pf
ceramic trimmer
NPO, 10/12m BPF
4
1
C52, C53, C54, C55, C58, C61, C62,
C63, C87, C95, C107, C108, C109,
C110, C113, C114, C115, C118, C119,
C120, C121, C129, C133, C141, C142,
C143, C145, C146 C155, C158, C159,
C160, C161, C162, C163, C164, C165,
C168, C170, C172, C175, C181, C183,
C184
.01
Red Monolithic Ceramic Caps
44
Appendix A
Picture
K2 RF Board Parts List
Designators
Value
Description
QTY
C59, C65, C67, C86, C124, C130, C131,
C135, C139, C151, C176, C178, C185
C6, C68, C70
C60, C137
C71, C174, C210
C72, C154
C74
C75, C225, C227
C76, C211
C84, C85, C202
0.1
5pf
100uF
82
270
20
470
10
120
Red Monolithic Ceramic Caps
NPO, 40m BPF; other
Electrolytic
NPO
NPO
NPO
NPO 100v (C75 for 160m OPTION)
NPO 100v
NPO 100v
C90, C94, C117, C138, C156, C157,
C162, C166, C196
C92, C177
C93
C96
D1, D2, D3, D4, D5, D6, D7, D36
.047
.022
10uF
1uF
1N4007
Red Monolithic Ceramic Caps
D10
D11, D13, D18
1N5821
1N4148
D16, D23, D24, D25, D26, D39
D17, D21, D22, D29, D30, D31, D32,
D33, D34, D37, D38
MV209
Varactor Diode. 2 pins
6
MVAM108
Varactor Diode. 2 pins
11
Electrolytic
Mono.(5kHz trap)
13
3
2
3
2
1
2
2
3
9
2
1
1
8
1
3
Appendix A
Picture
K2 RF Board Parts List
Designators
D9
1N34A
Description
Germanium. RF Power Detector; 1N270
Also OK; Glass Body
Heatsink
Heatsink TO5 Flush
crown Heatsink; 0.75" diameter
In Misc. Bag
HW
2-D,fastener
9
In Misc. Bag
HW
standoff, 0.158" x 1/4" D; Grey Plastic round Standoffs for PA
self retaining
transistors
2
HW
thermal insulator,
TO220
3
Note: All 4-40
Metal HW is in
HW
Misc. bag.
HW
HW
HW
HW
Value
#4 lock washers
4-40 nut
4-40 screw x 1/2”
4-40 screw x 3/16”
4-40 standoff
Adhesive; Grey-Blue;
internal tooth
for PA, Driver mounting
pan-head phillips, black ; for PA Trans.
Mounting
pan-head phillips, black
0.187”x 0.25”long threaded; round
QTY
1
1
14
3
2
32
2
Appendix A
Picture
K2 RF Board Parts List
Designators
HW
Description
washer, nylon, 0.5" diameter; Mounting for
T5 - VCO
#4, washer, nylon
nut, nylon; Mounting for T5 - VCO
4-40, nut, nylon
screw, panhead, nylon; Mounting for T5 4-40,screw, nylon x 1/2" VCO
J1
J10
J11
J12
J13
J14
Stereo Jack
3p,Female
12p,female
8p,Female
8p,Female
16p,female
Keyer Jack, Threaded; Vertical Orientation
SSB OPTION
SSB OPTION
NB OPTION
XVTR OPTION
160m OPTION
1
0
0
0
0
0
J2
Stereo+iso sw.
Headphone Jack; Horizontal Orientation
1
J3
J4
2.1mm jack
BNC
1
1
J5
J6
J7
3p,Female
6p,female
18x2,female
12V Power Jack; 2.1 mm Barrel, 5A
Antenna Jack
(opt for low-level AF output; usersupplied)
RF to Control board
RF to control board
J8
10x2,female
RF to control board
1
HW
HW
Value
QTY
2
2
1
0
1
1
Appendix A
Picture
K2 RF Board Parts List
Designators
J9
Packed in
K1, K2, K3, K4, K5, K6, K7, K8, K9,
Tube in Main K10, K11, K12, K13, K14, K15, K16,
K17
Box
keycap on/off switch
Value
3p,Female
Description
SSB OPTION
Latching Relay, 5V
OMRON Relays; Black; G6HU-2
Power Switch Cap; rectangular
L10, L11, L12, L13
Var,1uh; T1050
L16, L17, L18, L19, L20, L25, L26
T44-2 Toroid
L21, L22, L23, L24
T44-10 Toroid
L30, L1, L2, L3, L4, L8, L9, L34
Var,4.7µH; T1005
L31
L33
L5
12µH
39uH
33µH
P1
20p,male, RA
P3, P6
2p,male 0.156
TOKO Variable Can, 15/17m BPF, 10/12m
BPF; Small adjustment slot
80m LPF(2.66uH); 20/30m LPF(.579uH,
.435uH, .371uH); 1.36uH, 40M LPF; 0.44"
Diameter, Red
12/10m LPF(.32uH, .26uH);
17/15mLPF(.45uH); ; 0.44" Diameter,
Black
TOKO Variable Can, VCO, IF, 40m BPF,
80/160m BPF, 20/30m BPF; Large
Adjustment slot
solenoidal, shielded (PLL ref osc.),
DELEVAN; Black
solenoidal, shielded, DELEVAN; Black
solenoidal, Green; RFC (80/160m BPF)
To Front Panel, J1 (gold)
locking ramp; 12V Aux in; Battery, ATU
OPT
QTY
0
17
1
4
7
4
8
1
1
1
1
0
Appendix A
Picture
K2 RF Board Parts List
Designators
P5
Q10, Q12, Q17, Q20, Q23
Q11, Q13, Q16
Q18, Q19, Q24
Q2
Value
2p,male
2N7000
PN2222A
J310
ZVN4424A
Description
For Speaker; 0.1"; Locking Ramp; Brown
TO92
TO92
TO92
TO92a
Q5, Q21, Q22
Q6
2N5109
2SC2166
Pre-Amp, Post Amp, Pre-Driver; TO5
Driver; TO-220
3
1
Q7, Q8
R115
R1, R2, R10, R38, R39
R11, R12, R41
R111
R13, R14, R16, R31, R32, R65, R101
R15, R55, R56, R92, R97
R20, R46
R22
R28
R30, R48, R49, R61, R98
R33
R35, R36, R94, R113
R4
R40, R64, R72, R88, R90, R99
R42, R83
R43, R78, R112
R45, R47, R74
R5, R24, R25, R34, R44, R62, R66,
R73, R95, R96
2SC1969
0.05 ohm
1K
560
5.6K
10K
33
270
3.3M
27K
120
15K
82
1.3K
470
4.7
22
47
Push Pull PA Finals; TO-220
1%, 3W Current Sense Resistor; Black
2
1
5
3
1
7
5
2
1
1
5
1
4
0
6
2
3
3
2.7K
160m OPTION
QTY
1
5
3
3
1
10
Appendix A
Picture
K2 RF Board Parts List
Designators
R50
Value
1.5 ohm
Description
Driver Emitter Resistor
QTY
1
Appendix A
Picture
K2 RF Board Parts List
Designators
R53, R54
R58
R59
R6, R8, R89
4.7 ohm
180
4.7K
100
R60
R63, R77
R67
R68
R7
R75, R80
R76
R79, R81
R82, R84
R85
R9, R17, R37, R69, R107
R91, R93, R100
100, POT - Trimmer
220
1.5k
237
68
680
10
1.8K
18
150
100K
820
PA Bias Adj.
RFC1, RFC2, RFC11, RFC12, RFC13,
RFC16
RFC10
RFC14
100µH
1mH
FT37-43 Toroid
Soleniodal inductor; Green
5kHz trap, Green
100µH, 16T; Grey; 0.37" Diameter
6
1
1
RFC3
FT37-43 Toroid
60uH, 10T; T-R Input Choke; Grey; 0.37"
Diameter
1
RFC4, RFC5, RFC8, RFC9
10uH
RFC6
0.68µH
Value
Description
1/2W
1%
1%
Soleniodal inductor; Green
Solenoidal inductor; Driver Freq.
Compensation
QTY
2
1
1
2
1
2
1
1
1
1
1
2
2
1
5
3
4
1
Appendix A
Picture
K2 RF Board Parts List
Designators
RFC7
Value
15uH
Description
Soleniodal inductor; Green
QTY
1
Appendix A
Picture
K2 RF Board Parts List
Designators
RP2, RP6
Value
100K SIP; 8A3-104G
Description
8 Pin SIP,4R ISO, Yellow
QTY
2
RP3
RP4,RP5
10K SIP; 8A3-103G
100K SIP; 6A3-104G
8 Pin SIP,4R ISO, Yellow
6 Pin SIP,3R ISO, Yellow
1
2
S1
Socket
DPDT
28 pin socket
1
1
T1
FT37-43 Toroid
T2
FT37-43 Toroid
T3
FT50-43 Toroid
Power On/Off Switch
Skinny DIP socket for 16C72 uP
9:3 ; Pre-Driver to Driver; Grey; 0.37"
Diameter
12:8; Driver to PA Transformer; Grey;
0.37"" Diameter
10T bifilar; PA Collector Feed; Grey; 0.5"
Diameter
T4
Multi Ap Core
T5
T50-6 Toroid
T6
T7
TP1, TP2, TP3
FT37-43 Toroid
FT37-43 Toroid
test point, female
3:3:1:1, 2 Hole Balun Core; PA Output;
Grey
1.3uH, 16:4 ; 90% of core for primary; VCO;
-0.5" Yellow
10T bifilar,; RF preamp; Grey; 0.37"
Diameter
3:11 ; xfil to IF amp; Grey; 0.37" Diameter
VFO, BFO, PLL ref.
U1
U10, U11
U12
16C72
NE602AN
MC1350P
Relay Driver PIC; I/O Controller; OTP
programmed
TX Mixer; Prod. Detector
IF Amp / AGC
1
1
1
1
1
1
1
3
1
2
1
Appendix A
Picture
In Main Box
In Main Box
K2 RF Board Parts List
Designators
Value
Description
QTY
U2
U3, U9
U4
U5
U6
78L06AWC
LT1252
MC145170P1
LTC1451
LMC662
6v Reg. For relays
VFO Buffer; TX Buffer
PLL
12-Bit DAC for Reference Freq. Of PLL
(rail-to-rail out); PLL Loop filter
1
2
1
1
1
U8
78L05
1
W1, W2, W3, W5, W6
Wire
Wire
X1, X2
1" bare wire
#24
#28
12.096MHz
5-volt reg. (100mA); TO-92
Use Component Leads from resistors and
capacitors
For Toroids, Green and Red
For Toroids, Green and Red
HC-49 Crystal
X3, X4, X5, X6, X7, X8, X9, X10, X11
4.915Mhz
HC-49 Crystal
9
Z1, Z2
Ferrite Beads
2 ferrite beads ea. on bare wire (see text)
4
Z5
4.000MHz
Ceramic resonator w/caps; 3 pin; Blue
1
0
1
1
2
Appendix A
Picture
K2 RF Board Parts List
Designators
Z6
Value
TUF-1 Mixer
Description
Mini-circuits Mixer; 4 Pin metal rectangular
can.
QTY
1
Appendix A
Picture
K2 Misc. Items
Designators
Value
Cx
10pf
Cx
Heatshrink
.01
0.25" x 6"
HW
HW
HW
HW
2-56,screw x 1/8"
2-D,fastener
#4 lockwasher
4-40 nut
HW
4-40 x 3/8”
HW
HW
HW
HW
Jx
Misc
Misc
4-40,3/16”
shoulder washers, nylon
Tie wrap - Small
Tilt stand with 4 feet
mono 1/8” phone jack
green plastic filter
male pin
Description
For Freq. Probe
Red Monolithic Ceramic Cap; Bypass for external
speaker jack.
for Test Probes
fillister head, stainless, 2-56 x 1/8”,slotted; for front
Lexan bezel mount
(+ 9 from RF bill of materials)
speaker mounting; feet
pan-head phillips screw, black anodized ; spkr; FPctrl bd; feet; top 2 hole plugs.
pan-head phillips screw, black anodized (includes 4
spares)
For PA transistor mounting. Black.
For ext speaker wire
(Tilt Stand, Left Front/ Right Feet; Rear Feet)
w/switch, panel mount (ext. speaker jack)
For bar graph LED array;(In envelope.)
For Freq. Probe (In envelope.)
QTY
1
1
4
2
12
10
14
14
2
3
1
1
1
1
Appendix A
Picture
K2 Misc. Items
Designators
Misc
Value
female crimp pins
Description
for speaker to RF board connector (larger pins for
brown shell)
QTY
2
Misc
female crimp pins
Misc
Misc
wire, 2 conductor
plastic tuning tool
Misc
Misc
Other
Other
Allen wrench
Allen wrench
TO-5 Insulative spacer
Crystal Ins. Spacer
for test cable connectors (smaller pins for white
shell. In envelope.)
(24”) speaker wire, dual conductor#22 AWG
stranded
for VCO and BPF slug-tuned inductors
long-handled for large knobs and for Control board
removal;(In envelope.)
short-handled for small knob; (In envelope.)
Only needed for Rev. XC
Only needed for Rev. XC
Px
2p female conn. Housing
0.1” spacing; locking ramp.; brown; for speaker
1
Px
Px
Px
Wire
Wire
2p female conn. Housing
2.1mm male conn.
stereo 1/8” phone plug
Coax, RG-174
Green hook-up, solid
0.1” spacing, white (for test probes)
2.1mm male; Mates with DC power jack)
(for key/keyer/paddle input)
For Freq. Probe (In envelope.)
General use
1
1
1
8"
2'
3
1
1
1
1
3+
11+
Appendix A
Designators
K2 Box Contents
Value
Bag, Front Panel Parts
Bag, Control Parts
Bag, RF Parts
Bag, Misc. Parts
Description
QTY
Includes H/W for all Boards
1
1
1
1
B1
B2
B3
left side
right side
front panel
K2 enclosure
K2 enclosure
K2 enclosure
1
1
1
B4
B5
B6
rear panel / heatsink K2 enclosure
top cover
K2 enclosure
bottom cover
K2 enclosure
1
1
1
K1, K2, K3, K4, K5,
K6, K7, K8, K9, K10,
K11, K12, K13, K14,
K15, K16, K17
Manual, K2
PCB
PCB
PCB
SP1
Wire, Enameled
Wire, Enameled
Wire, Enameled
Wire, Enameled
Wire, Teflon
Latching Relay
Front Panel
Control
RF
Speaker
Red #24
Green #24
Red #28
Green #28
White, #22
5V, OMRON; Black; G6HU-2; Used on
RF Board; Packed on plastic tube.
K2 Assembly, Operations Manual
4 ohm
For LPF's, RFC's and Transformers
For LPF's, RFC's and Transformers
For pre-amp transformer
For pre-amp transformer
For PA output transformer
17
1
1
1
1
1
1
1
1
1
1
20
15
S23
S22
S21
S20
S19
S18
S17
S16
S15
S14
S13
S12
S11
S10
S9
S8
S7
S6
25
/BANK1
1B,C,DP
1A,G,D
1F,E,AN
2B,C,DP
2A,G,D
2F,E,AN
3B,C,DP
3A,G,D
BAND+
RECALL
F. ENTRY
S1
7
10
3F,E,AN
4B,C,DP
4A,G,D
4F,E,AN
5B,C,DP
5A,G,D
5F,E,AN
6B,C,DP
6A,G,D
6F,E,AN
7A,G,D
7F,E,AN
8B,C,DP
8A,G,D
8F,E,AN
DS1
S5
S4
S3
S1
30
7B,C,DP
Backlight
LEDs
S2
S0
5A
3
4
5
R9
R11
470
40
35
6
ANT1/2
TUNE
S4
STORE
F. ENTRY
D6
S11
D1
S5
S0
S1
S2
S3
S6
15
S4
S7
BP2
BP3
BP0
BP1
S10
VLCD
S8
S11
10
MENU
EDIT
S5
NB
LEVEL
S6
D7
RATE
LOCK
#0
S7
D0
D3
5
3
4
2
C9
1
/MIC RD
/BANK2
/BANK1
/SPD RD
8
11 12 13 14 15 16 17 18 19 20
R15
10K
5A
7
DS2
6
R16
15K
.01
LED Array
5
6
S0
9 10
8
4
7
7
D6
S14
RIT
PF1
#7
XIT
PF2
#8
S15
S16
MSG
REC
#9
D0
D7
First switch label corresponds to switch TAP,
Second label corresponds to switch HOLD.
Third labels are special cases:
1. S1 and S2 are pressed simultaneously
to enable direct frequency entry.
2. S7-S16 are used as a numeric keypad
(#0 through #9) for direct frequency
entry, memory recall, etc.
3
8
6
D2
XFIL
AFIL
#6
Pushbutton Switches
2
9
10
5
S13
100K
2V
R12
120
4
AGC
CW REV
#5
S12
D1
RP1
D0 D1 D2 D3 D4 D5 D6 D7
IDAT ICLK
3
PRE/ATTN
SPOT
#4
20
1
2
D3
D4
D5
21
S9
S12
A2
VSS
A1
SA0
S15
A0
S13
S16
OSC
5
25
S14
S17
CLK
S18
S20
SCL
/SYNC
1
VDD
S21
SDA
4.0V DAY (18mA/LED)
2.7V NIGHT (6mA/LED)
(based on LED Vf=1.9V)
120
D4
BAND-
U1
PCF8566
30
S19
S22
S23
PN2222A
RP2
A=B
SPLIT
#3
(S0 through S23 connected to DS1; only S0 and S23 shown)
Q2
C1
.047
S10
S23
/NIGHT
Q1
S9
/BANK2
R10
33
LCD Driver
A/B
REV
#2
/BANK1
D5
S3
220
S8
COM1
VIM-838-DP 8-DIGIT LCD
COM2
2
COM3
1
COM3
COM1
D3
COM2
D2
Bargraph
Brightness
Control
DISPLAY
RF/ALC
S2
D2
5A
/BANK2
MODE
VOX
#1
(spare)
9 10
ENC A
ENC B
11
10
3
19
13
8
12
9
2
10
3
19
11
13
8
12
9
2
5
4
3
14
13
6
H
G
F
E
D
C
R1
8
16
7
9
10
/SPD RD
D4
R2
SR CK
SR DOUT
5A
U3
SR WRT
C2
.01
cw
ccw
C3
.047
/SR RD SR CK SR DIN 5A
U4
TPIC6B595N
10K
Keyer Speed
GND
VCC
/QH
QH
SER
CLK
12
15
5A
5A
U2
74HC165
2
11
1
B
A
SH/LD
2
1
3
CLK INH
18
17
/Q7
SOUT
GND
GND
16
15
/Q4
/Q6
/Q5
SIN
SRCK
GND
14
6
5
7
/SRCLR /Q3
/Q2
RCK
4
/Q0
/Q1
/G
VCC
17
16
15
18
SOUT
GND
/Q7
GND
/Q6
/Q5
SIN
GND
7
6
5
14
/Q4
SRCK
/SRCLR /Q3
/Q2
RCK
/Q0
/Q1
/G
4
V+
B
A
V-
VCC
Z1
Shaft Encoder
1
4
/ENC RD
10K
Power Out
TPIC6B595N
/BANK1
cw
ccw
To RF Board, P1
D5
J1
5A
7
GND
8
8
GND
13
14
15
16
17
18
19
R5
R4
20
V POTS
10K
RIT/XIT Offset
R.F. Gain
/DOT-PTT
/BANK2
cw
5A
ccw
cw
ccw
D6
1N5817
Q3
C8
5
RP3
10K
2N3906
V POTS
2
4
R13
68.1K, 1%
R7
4.7K
V POTS
RP3
10K
.01
C4 C5 C6 C7
.01 .01 .01 .01
P1
Mic Config.
12
5A
R14
R3
R6
RP3
cw
100K
5A
AF Gain
1
ccw
3
/MIC RD
4.7K
IDAT
6
5V
7
11
ICLK
5
6
10
MIC AF
6
FUNC
5
9
/SR RD
4
UP
8
ENC A
DN
7
SR CK
3
3
4
6
SR DIN
PTT
5
10K
RP3
10K
7
4
SR WRT
2
2
8
3
SR DOUT
AF
2
AUXBUS (NC)
1
1
1
ENC B
J2
Mic
5K (audio taper)
These components are supplied with option K2-SSB.
See manual for mic configuration.
Elecraft
K2
Front Panel Board
By W. Burdick Rev.
E. Swartz
=
X C
Date
Sht.
1/25/99
On bottom of PC board.
Appendix B
©1999 Elecraft
1 of 1
3
1
P4
2
2
2
1
3
4
D3
1N5817
HOST
8T
R21
10K
1
-
C31
0.1
AUXBUS
Q8
PN2222A
+
1
40
5A
MCLR
V SMTR
6
5
V ALC
.001
I SENSE
8
7
3
9
10
4
2
1
RB5
IDAT
RB4
/SR RD
.01
RB3
RA4
RB2
SR CK
V POTS
RA5
RB1
SR WRT
ENC A
RE0
RB0
SR DIN
/SLOW AGC
RP3
47K
RP2
82K
RA3
V SENSE
8R
C5
RA1
/AGC OFF
RE1
VDD
RE2
VSS
1
V PWR
V RFDET
3
4
RP7
33K
5A
4
RP4
5
C39
.01
RP5
470
4.000MHz
RP5
470
RP4
82K
3
82K
5A
X2
C21
33
6
15
3
2
1
C37
.01
2
Q9
MPS5179
MPS5179
/DOT-PTT
RD5
RX
OSC2
RD4
TX
RC0
RC7
RC1
RC6
25
RC2
RC5
SCK
RC3
RC4
/DAC2CS
RD0
RD3
RD1
RD2
VDD
PDE
DGND
SCLK
DOUT
/CS
2
1
2
/DAC1CS
3
RP7
33K
4
/CS
VCC
SDO
/HOLD
/WP
SCK
VSS
7
2
-
1%
7
5A
6
A u d i o
F i l t e r
PD2
SCK
5
SDI
SDO
AUXBUS
1
2
R19
1.5K
J2
Q11
(20mA res.)
SCK
/DAC2CS
/DOT-PTT
PD2
AUXBUS
V ALC
V BIAS-XFIL
8T
EXT ALC
8R
12V IN
V POTS
IDAT
12
14
16
18
20
22
24
26
28
30
32
34
36
2
4
6
8
10
12
14
16
18
5
20
5
7
9
11
13
15
17
19
21
23
25
27
29
31
33
35
1
3
5
7
9
11
13
15
17
8
7
3
4
5
P2
6
P1
To RF Board, J6
To RF Board, J7
P3
To RF Board, J8
SDO
/DASH
VOL1
/PLLCS
AF OUT
PD1
V BFO
8T
8
8R
2
8R
ENC B
10K
SR WRT
RP6
SR DIN
12V 5A 8A
V AGC
ICLK
C3
.01
R16
10
On bottom of PC board.
12V
220µF
C28
220µF
7
AF Amp
C41
.01
Elecraft
K2
Control Board
By W. Burdick Rev.
=
10
C29
AF OUT
10K
1
6
RP4
82K
19
9
+
3
+
22µF
+
10
C32
8
8
8
NC BYPASS
6
1
RP5
470
R20
2.7
R.F. GAIN
6
X1
5.068MHz
I.F. OUT
RP4
82K
C30
.047
1
RP6
1
4
7
3
5
2
LM380N-8
U2A
LM833
R1
C7
330
2
6
4
VOL1
7
U9
5A
4
R2
3.3M
8A
100K
VOL2
v+
C8
39
12V 5A 8A
IN1
8R
10K
7
C10
.01
9
1
2
nc
6
8
+
C2
.001
RP6
2
3
.001
5
3
RP6
10K
D1
1N4148
5
V-
RX
V RFDET
10
8A
7
U2B
.022
C27
OUT
1
+
5
2
VOL2
GND
R3
33K
-
4
8
Q4
Q12
PN2222A
33K
6
V+
7
IN2
8
1
C26
0.1
GND
R5
C25
0.1
2N7000
6
RP1
3.9K
C11
C9
.01
5
D
C23
.01
V SMTR
2
8A
U1
NE602
+
/SLOW AGC
.047
D
10
Q7
J310
G
3
C6
.047
C19
.047
Q2
2N3906
G
RP1
3.9K
8R
5A
S
Q6
4
D2
1N4148
OUT
GND
C14
10M
/MUTE
J310
Q3
C4
0.47µH
RP6
10K
3
S
TX
9
78M05
IN
1.96k, 1%
AGC
Mute
U5
R7
I SENSE
C1
2.2µF
1
2
5V Reg.
PN2222A
0.00-5.10A
2
R17
3
V SENSE
U3B
/AGC OFF
4
RP1
3.9K
SR CK
196K, 1%
.047
AF OUT
7
5
Q1
2N3906
LMC6482AIN
-
4
J1
C16
ENC A
+
6
3
R18
C15
R10
PD1
12V
1.5K
8V Switching
100µF
4
/SR RD
5
U3A
+
47K
8T
C13
22µF
1
3
0-25.5V
(0.1V res.)
SR DOUT
C17
.01
10
9
RP3
8
U7
25LC160
+
R9
806K, 1%
+
100
Voltage Sense
8
EEPROM
8A
OUT
GND
V BIAS-XFIL
-
U10C
RP2
1
IN
47K
+
U4
8
U10D
7
RP3
9
8
/EECS
LM2930T-8
R8
25V max.
8
6
82K
8V Low-Dropout Reg.
1
RP2
5
10
2
12V
Note: Current sense resistor
is R115 on the RF board.
11
11
9
5A
INT (12V)
14
-
10
/CLR
MCU
S1
V BFO
+
13
5A
HOST
21
Current Sense
EXT.
8A
4
12
U8
MAX534
16C77
P5
.01
C40
.001
U6
12V IN
2.2µF
U10B
12
8
1
Volt Meter Input
- +
C36
.0027
5A
13
DIN
+
7
-
C35
.01
7
82K
20
/PLLCS
AGND
UPO
7
C20
TONE
C33
6
14
REF
/LDAC
4
/DASH
OSC1
/MUTE
COUNT
P6
RD6
ENC B
C22
8-50
Q10
100kHz-40MHz
RD7
VSS
30
4
C38
680
1
Freq. Ctr
Input
VDD
5
6
5V FCTR
LMC660
5
6
5
15
OUTD
OUTA
3
10
EXT ALC
2
4
16
OUTC
OUTB
5A
3
RP7
33K
Q5
2N7000
Quad, 8-bit DAC
SR DOUT
35
8
.0027
TONE
5
ALC
12V
C12
.001
RA2
RP3
47K
+
6
5
ICLK
RB6
RP3
47K
C24
AUXBUS
RB7
RA0
C34
R6
470
TONEVOL
Aux I/O
RP7
33K
.01
8A
LMC660
82K
RP2
SIDETONE
C18
U10A
V PWR
E. Swartz
X C
Date
1/25/99
Sht.
1 of 1
Appendix B
©1999 Elecraft
PLL Reference
Oscillator (VCXO)
12.096MHz
Q19
J310
X1
D18
1N4148
PLL Synthesizer
C89
5B
8B
TP3
1
OSCIN
G
5
X2
C86
0.1
S
C84
120
RP2
100K
3
R22
3.3M
PDOUT
DIN
VSS
RP2
D17
MV209
100K
R25
12
6
2.7K
R30
7
/PLLCS
LD
CLK
FV
DOUT
FR
10
7
8
+
C92
.022
9
5
K15
1
SCK
3
/DAC2CS
8B
8A
CLK
VCC
DIN
VOUT
LD /CS
REF
DOUT
GND
4
8
IN
8
7
3
6
2
+
1
-
6
RX VFO
4
R14
10K
C61
.01
R33
15K
nc
R11
560
R12
560
8
8B
8B
3
C63
.01
2
9
nc
D21
Q17
2N7000
D22
MVAM108
8
C76
10
C74
20
VFO ALC
G
D11
1N4148
S
3
K13
1.6Vpp
R9
100K
D
C60
100µF
OUT
U6A
LMC662
T5
1.2µH
3
-
4
C58
.01
R10
1K
2
4
5
12-Bit DAC
9
7
C90
.047
C103
220µF
C175
.01
1
2
C73
47
RP3
10K
RP3
10K
C70 C71
5pF 82
R16
10K
C59
0.1
8
3
(Vout = 0 to 4.096V)
+
9
7
+
2
SDO
RFC16
100µH
7
3
+
U5
LTC1451
5B
U8
78L05
U3
LT1252
TX VFO
C64
.001
TP1
2
7
8B
Buffer
2
4
5B
D13
1N4148
3
Relays are shown in RESET
position. See relay table (sheet K14
3).
8
R13
10K
4
D26
1
VFO Range Selection
7
D25
4
RP2
100K
R17
100K
10K
R32
10K
RP3
10K
C93
10µF
Q18
J310
S
2
U6B
LMC662
6
U4
MC145170
D
G
R31
120
R20
270
C100
.001
D23
5
2.7K
11
/ENB
C65
0.1
33
D24
-
6
RFC14
100µH
3
D16
MV209
FIN
RFC10
10mH
27K
+
4
R24
13
SCK
2
PH R
REFOUT
R15
8B
C68
5
7
14
C67
0.1
VFO
R28
RP3
10K
15
4
SDO
C87
.01
C85
120
1
16
VDD
PH V
OSCOUT
L30
4.7µH
C96
1µF
.01
C94
.047
8
5
6
RP2
100K
8B
.001
D
2
L31
12µH
C95
C75
470
C62
.01
Q16
PN2222A
C72
270
4
Key/Keyer/Paddle
J3
2
4
6
8
10
12
SCK
/DAC2CS
/DOT-PTT
AF OUT
PD2
V ALC
AUXBUS
8T
EXT ALC
12V IN
8R
V POTS
ENC A
SR DOUT
16
18
20
22
24
26
28
30
32
34
2
36
C196
.047
6
8
10
12
14
16
18
9
11
12V 5A 8A
13
15
17
19
21
SR DIN
23
25
27
29
31
33
1
35
3
VOL1
5
7
9
11
13
15
17
+
-
19
SDO
7
/DASH
5
/PLLCS
3
R115
F r o n t
C106
2.2µF
P a n e l
8R
B o a r d
OFF
18
19
R113
82
20
R.F. GAIN
17
5A
16
IDAT
15
ICLK
14
V POTS
13
ENC A
12
/SR RD
11
SR CK
10
SR DIN
9
SR WRT
8
SR DOUT
7
AUXBUS
6
ENC B
5
S1
Power
Q23
2N7000
8T
+
P5
4
MIC AF
2
3
/DOT-PTT
2
VOL1
1
J2
Elecraft
Speaker
C111
2.2µF
=
©1999 Elecraft
(See control board)
P1
1
Phones
ON
0.05 , 1%, 3W
Current Sense
+
2
12V IN
12V
R36
82
+
D10
1N5821
P3
Aux. 12V
20
1
AF OUT
V AGC
R.F. GAIN
I.F. OUT
1
8R
4
J8
6
PD1
5
V BFO
4
ENC B
3
8T
2
VOL2
C105
2.2µF
14
8R
/DOT-PTT
1
AF OUT
R35
82
12V DC
VOL2
J7
C1
.001
/DASH
C2
.001
V BIAS-XFIL
J6
SR WRT
1K
SR CK
1K
12V 5A 8A
ICLK
R1
/SR RD
R2
IDAT
C o n t r o l
B o a r d
V RFDET
J1
On bottom of PC board.
K2
By W. Burdick Rev.
E. Swartz
X C
RF Board
Date
Sht.
1/25/99
Appendix B
1 of 4
C165
8R
12V
C52
.01
R72
470
R73
2.7K
K16
C142 .01
.01
R82
C160
.01
C143
.01
9
2
C141
.01
9
2
C53
.01
RFC12
100µH
R78
22
RX VFO
18
N o i s e
B l a n k e r
C158
+7dBm
R74
47
7
4
7
K17
4
J12
8
3
8
3
.01
R81
C159
.01
4
RFC11
100µH
C163
1.8K
1
2
3
4
5
6
R7
68
R6
100
R8
100
Z6
C145
.01
T6
4
1
12V
2
C161
.01
3
TUF-1
Q21
2N5109
BPF
Attenuator
R5
R75
680
-10dB
2.7K
-6dB, Z= 150
R89
2N5109
680
R83
4.7
R79
1.8K
100
W5
NB Bypass
R88
470
R84
18
R90
470
+14dB
C164
.01
C146
.01
R77
220
Buffer
.047
8R
Q22
R80
RF Preamp
R76
10
D7
1N4007
C170
3
Rcv. Mixer
(Sh. 3)
AUXBUS
D6
1N4007
1
8
.01
12V
2
7
C162
.01
8R
R85
150
HI IP
Q12
2N7000
Post-Mixer Amp.
R97
33
12V
C151
U9
LT1252
0.1
7
R96
2.7K
Variable-Bandwidth Crystal Filter
3
+
6
2
C54
.01
IF Amp
V BIAS-XFIL
-
R92
4
33
R95
R93
820
R101
10K
2.7K
RFC13
100µH
RP4, RP5:
V XFIL2
C185
Product Det.
and BFO
8R
C166
100K
R112
22
0.1
U12
RP4
R94
82
RP4
3
1
RP5
3
RP5
5 .047
5
C150
W2
X7
X10
X9
2
1
T7
6 D34
4
2
X8
3
RP5
3
1
C157
.047
8T
D29
RP4
5.6K
1
MC1350
4
C55
.01
4
2
2N7000
6
W3
X11
5
330
6
7
8
C178
R107
100K
X6
820
0.1
D31
D29-D34:
4
MVAM108
3
J9
2
3
4
5
6
7
8
9
10
11
22
D39
MV209
S S B
2nd Xtal Filter
6
MIC AF
V RFDET
8T
/DOT-PTT
AUXBUS
PD1
7
C174
V BFO
82
1
R98
120
8A
EXT ALC
X3
C168
RP6
C173
220
XFIL Out
8R
8T
C177
.022
V3
V AGC
C183
.01
PD2
5
12
XFIL In
C156
.047
1
J10
1
Xmit Mixer
2
C176
0.1 2
C180
C184
.01
3
1
V+
C181
.01
SSB Control
J11
2
2
1
C182
180
I.F. OUT
1
3
NE602
8
D33
D32
Aux. AF
U11
X5
4
D30
R91
820
R100
8A
L34
4.7uH
AGC
2
J5
V XFIL2
R111
Q20
100K
8
.01
2
X4
7
RP6
100K
D38
MVAM108
V ALC
L33
Q24
J310
A d a p t e r
39µH
D
D37
G
TP2
4
3
8
5
4
V+
1
C153
39
*
U10
NE602
.001
2
5
C169
390
C167
R99
470
V3
6
7
C154
270
D36
1N4007
6
C172
.01
RP6
100K
C155
.01
* Remove C167 when SSB Adapter is installed.
TX VFO
RP6
100K
MVAM108
S
C144
100pF
BFO Buffer/Attenuator
Elecraft
K2
By W. Burdick Rev.
E.Swartz
=
X C
RF Board
Date
Sht.
1/25/99
On bottom of PC board.
Appendix B
©1999 Elecraft
2 of 4
4
3
L1
C7
100
5
C6
C4
820
2
L2
40m
X v e r t e r
I n t e r f a c e
8
C8
820
4.7µH
4.7µH
1
2
20m/160m
3
L3
4.7µH
K3
8
K2A
R4
820
80/160m
2
3
4
5
6
7
8
RFC2
100µH
D2
1N4007
C114
.01
1N4007
D3
D4
C24
47
4.7µH
C21
C23
8-50pF
R39
1K
R37
D5
R38
1K
XVTR
Bypass
7
8-50pF
9
8
8
2
K9A
C109
.01
Q2
T-R
Switch
(Sh. 4)
8
3
K6
8
2
C211
10
Low-Pass Filters
C210
82
K10A
C46
5-30pF
K7B
IN
12V
OUT
AUXBUS
C139
9
U1
160RY
RXRY
1
28
RA1
RB5
K3
RB4
K1
RA2
K14
RA3
RB3
K4
RA4
RB2
K5
RA5
RB1
K7
VSS
RB0
K6
OSC1
VDD
/CLASS AB
160m-K1
K3
K8
K12
K4
K9
K9
K11
K11
K6
K7
K10
K10
K13
K13,
K14,
K13,
K13,
K15
K13,
K13,
1
C39
20
OSC2
VSS
RC0
RC7
RC1
RC6
RC2
RC5
K11
RC3
RC4
K12
10
.001
HI IP
14
10
8
3
2
C225
C226
470
820
K10
C227
470
9
K12A
K12B
RF Output Detector
R67
1.5K
D9
V RFDET
1N34A
2.7K
1%
R68
237
1%
C77
R69
100K
.001
K9
ALL RELAY BYPASS CAPACITORS ARE .001µF
C207
LPF
Relays
C17, C27, C195, C204, C207, C216
C216
RY COM
C223
C57
.001
Elecraft
C208
.001
=
©1999 Elecraft
7
L26
40m
K8
C195
All relays are single-coil latching type
and are shown in the RESET position.
Relay pins 5 and 6 are not connected internally.
K11B
15
K17
C204
NOTE:
1
10
Pre/Attn.
Relays
K16
K14, K15
K15
L25
R66
C82
.001
K14
K15
K14, K15
K15
25
C17
K2
K2,
K1
K3,
K4
K5
K5,
K6,
K7
Z5
4.0MHz
VCO
9
C222
100
C220
220
4
K2
10
SET Relays
160m
80m
40m
30m
20m
17m
15m
12m
10m
1
RB6
5
LPF
10
RA0
K13
K15
C218
150
C221
39
RB7
1
VCO Relays
8
C219
12
K11A
BPF Relays
MCLR
L24
3
C140
.001
PIC16C72
C81
C79
Band-Pass Filters
C80
0.1
C9
C48
220
C26
1µH
C27
10/12m
C37
1µH
BPF
K10B
7
L23
R64
470
6V
8
L13
6V
C49
L12
C42
220
C214
68
C212
2
U2
78L06
C47
33
2
C38
C45
BPF
(Sh. 2)
Band
17/15m
I/O Controller
7
C43
33
2
9
C213
33
7
4
5-30pF
4
3
L22
3
12/10m
C104
68
C203
47
7
L21
(Sh. 4)
K5B
K9B
C201
220
C199
220
C197
100
ZVN4424A
9
C202
120
C200
150
C198
27
LPF
PRE-DRIVER
9
7
L20
L19
3
4
K7A
9
1200
150
12m/15m
C44
C192
C191
1800
L18
30/20m
4
C107
.01
RFC7
15µH
8
C36
330
10m/17m
K5A
7
K8B
C113
.01
100µH
D1
1N4007
C35
56
L11
1µH
2
L17
C190
1200
2
G
8T
15/17m
L10
1µH
R65
10K
16
3
RX Ant.
Bypass
7
2
C30
330
15
L16
D
9
C34
5-30pF
14
4
4
R34
2.7K
S
4
5-30pF
13
100µH
RFC1
K4B
3
C33
C32
12
80m
RFC3
100K
1N4007
8
C25
330
K4A
3
11
160RY
W1
8R
2
10
8R
L9
C19
C31
56
9
9
K2B
L4
4.7µH
20/30m
2
8
1
7
4
L8
4.7µH
330
7
AUXBUS
W6
C22
3
C20
3
6
8R
8
C16
1800
C110
.01
47
5
K8A
30m/80m
4
4
RXRY RY COM
6V
8T
3
P6
Aux. RF
C108
.01
7
C15
560
1200
C11
1800
2
C14
2
8R
9
3
1
33µH
C13
C12
560
1 6 0 m /
R X
A n t.
J13
K1B
L5
6V
J14
9
K1A
4
J4
Ant.
7
C5
100
On bottom of PC board.
K2
By W. Burdick Rev.
E. Swartz
X C
RF Board
Date
1/25/99
Sht.
3 of 4
Appendix B
12V
RFC4
10µH
+
C119
.01
C126
47µF
C133
.01
R45
47
C135
0.1
Z1
C127
RFC5
T2
10µH
12:8, FT37-43
680
Q7
2SC1969
2
3
LPF
C122
56
C115
.01
1
RFC8
10µH
R53
4.7
4
R55
33
(Sh. 3)
C129
.01
5
6
C
A
1
3
R58
2
4
1/2W
T3
2
RFC6
R54
4.7
R49
3
C116
33
8T
C120
.01
C121
.01
120
R56
33
RFC9
10µH
D
C130
0.1
180
7
8
0.68µH
4
Q8
1
T4
2:3:1:1
2SC1969
T1
9:3, FT37-43
R44
2.7K
B
C128
680
Q6
2SC2166
R40
C118
470
.01
R48
120
Z2
R47
47
C131
0.1
R50
Q5
2N5109
PRE-DRIVER
Power Amplifier (PA)
1.5
(Sh. 3)
+
C124
C125
22µF
0.1
R42
Driver
4.7
R41
560
S
C117
R43
22
Q10
2N7000
0.047
8T
PA Bias
G
D
8T
R46
270
R59
4.7K
Pre-Driver
R61
120
Q13
PN2222A
V BIAS-XFIL
Q11
PN2222A
+
2N3906,
PN2222A,
2N5109
MPS5179
2N7000
R60
100
J310
C137
100µF
C138
PA Bias Set
.047
CCW = MIN BIAS
S
G
D
E
B
C
D
S
G
C
B
E
/CLASS AB
R63
220
R62
2.7K
Elecraft
K2
By W. Burdick Rev.
E.Swartz
=
X C
RF Board
Date
Sht.
1/25/99
On bottom of PC board.
Appendix B
4 of 4
T-R
BANDPASS
FILTERS
T-R
T-R
POWER
AMP
(10W)
DRIVER
LOW-PASS
FILTERS
AGC
4.915MHz
ATTEN.
AND
PREAMP
POSTMIXER
AMP
RCV
MIXER
NOISE
BLANKER
XMIT
MIXER
BUFFER
PLL
SYNTH.
VCO
6 - 24MHz
KEY
Common
Transmit
Receive
T-R
MCUAND
SUPPORT
CIRCUITS
CRYSTAL
FILTERS
T-R
BAL.
MOD.
I.F. AMP
PROD.
DETECTOR
BFO
4.915MHz
AFAMP
DISPLAY
ANDCONTROLS
ELECRAFT K2 BLOCK DIAGRAM
W. Burdick/E. Swartz
K2 Appendix C © 1999 Elecraft. All rights reserved.
Rev. XC