The PFR-3A Three band “Portable Field Ready” QRP CW

The PFR-3A
Three band “Portable Field Ready” QRP CW Transceiver
40/30/20 meters
Hendricks Kits – www.qrpkits.com
KD1JV Designs
11/16/09
updated 3/1/10
PFR-3 shown with optional paddle installed.
Specifications:
Bands : 40 meters, 30 meters and 20 meters
Tuning range: Full band coverage
DDS VFO with 50 Hz slow tuning rate and 100 Hz fast tuning rate
Mode: CW only
Receiver MSD: 0.2 uV typical
Selectivity : 300 Hz
Four crystal IF filter and 600 Hz center frequency audio band pass filter
Receive current, no signal typical:
Active, 47 ma
Idle, 34 ma
Transmitter:
5 watts at 12.0 volts, all bands
Transmitter current: 650 ma (40 M) to 750 ma (20 M) typical at 5 watts.
Spurs: - 50 dBc maximum, all bands
5 to 40 wpm internal iambic keyer
Selectable A or B mode
Two (2) 63 character keyer memories.
Coax or balanced line output
Built in BLT (balanced line tuner)
Size: 7.2” wide X 4.2” deep X 1.5” high (less knob height).
Weight: 18 oz, no batteries installed.
Power supply voltage: 8 volts minimum, 12.5 volts maximum. 12 to 9 volts recommend.
External power or internal battery pack
1
Table of Contents
Parts placement overview. .....................................4 Tuning:.............................................................17
Group 1 assembly, Microprocessor and display:....6
Tuning limits:..............................................17
Modification:.....................................................7 RIT (receiver incremental tuning)........................18
Group 1 smoke test:...........................................7 DFE mode (direct frequency entry)......................18
Group 2 Assembly, receiver section:......................8 MENU switch (Keyer functions) : .....................18
Group 2 modifications:......................................9 Sending a Message:........................................18
Group 2 smoke test:.........................................10 Changing keyer code speed:............................18
DDS frequency calibration and precise BFO Tune Mode:...........................................................18
setting adjustment:......................................10 Storing a message:................................................18
Entering Calibration modes:.......................10 Selecting Iambic A or B modes............................19
Reference frequency calibration:................10 The difference between A and B modes:.........19
IF offset adjust and BFO trimmer set:.........10 Straight key mode:................................................19
BFO adjustment: ........................................11 Using the SWR bridge and BLT tuner:.................19
Group 3 assembly: Transmitter section................11 Using the BLT with end feed wire antennas or
Pretests:............................................................11 coax. ...............................................................20
Group 4, low pass filters:......................................12 Using a speaker instead of headphones:...............20
Group 5, SWR bridge and balanced line tuner:....13 Fuses: ..............................................................20
Winding T3:.....................................................13 Paddle wiring:.......................................................20
Final tests:.............................................................15 PFR front panel controls and rear panel connectors.
Power output....................................................15 ..............................................................................21
Mounting the board in the cabinet and final wiring: Troubleshooting:...................................................22
..............................................................................15 Bad parts:.........................................................22
Photo of back panel wiring..............................16 Troubleshooting steps: Divide and conquer....22
Battery holder mounting:.................................16
Group 1, the processor and display:............22
Operation:.............................................................17
Group 2, the receiver:..................................22
Power supply:..................................................17
Still no luck getting the rig to work? ..........23
Power switch:..............................................17 Schematics:...........................................................25
Power save mode:.......................................17 Receiver audio.................................................25
Selecting operating band:.................................17 CPU, DDS, Tx ................................................26
2
Parts check list:
QTY
VALUE
QTY
VALUE
1
10 ohms
Brown, black, black, gold
3
4.7 p or 5p NPO
Disk, brown, black dot on top edge
1
51 ohms
Green, brown, black, gold
3
22 p NPO
Disk, brown, black dot on top edge
5
270 ohms
Red, Violet, brown, gold
3
47 p C0G
Disk, brown, black dot on top edge
1
470 ohms
Yellow,violet,brown,gold
5
1K
Brown, black, red, gold
1
68 p NPO
Disk, brown, black dot on top edge
14
2.2 K
Red, red, red, gold
9
100 p C0G
Mono, yellow or NPO disk
3
4.7 K
Yellow, violet, red, gold
3
150 p C0G
Mono, yellow
3
10 K
Brown, black, orange, gold
2
220 p C0G
Mono, yellow
4
22 K
Red, red, orange, gold
3
330 p C0G
Mono, yellow
1
47 K
Yellow, black, orange, gold
1
560 p C0G
Mono, yellow
2
100 K
Brown, black, yellow, gold
1
680 p C0G
Mono, yellow
2
220 K
Red, red, yellow, gold
2
470 K
Yellow, violet, yellow, gold
2
470 p DISK
Disk, brown
3
1 MEG
Brown, black, green, gold
4
.001 ufd disk
Disk, brown
1
50K audio
Vertical PCB mount
3
51 ohm 2W
Green, brown, black, gold
21
0.1 ufd X7R
Mono, yellow
2
SA612AN
8 pin DIP IC
3
0.01 ufd film
Film, green
1
LM358N
8 pin DIP IC
1
30 p trimmer
Green
1
LM386N
8 pin DIP IC
3
poly-variable
Variable capacitor, dual section
1
74AC02N
14 pin DIP IC (74HC02 may be supplied)
1
0.47 ufd / 50V
Aluminum electrolytic
1
ATMEGA48
28 pin DIP IC
2
10 ufd /16V or 25V
Aluminum electrolytic
1
78L05
TO-92 plastic
3
100 ufd /16V or 25V
Aluminum electrolytic
2
2N3904
NPN TO-92 plastic
1
330 ufd /16V or 25V
Aluminum electrolytic
1
1N5817
Plastic diode shottky rectifier, 1A
4
8 pin DIP sockets
1
1N4756A
Larger glass diode, 47V 1W zener
1
14 pin DIP socket
4
1N4148
Glass diode
1
28 pin DIP socket
1
FQPF7P06
TO-220 plastic P MOSFET
2
FT37-43
Ferrite core, gray or black
1
2N3819
N-jfet
6
T37-2 Red
Powdered iron core
3
2N7000
TO-92 plastic N MOSFET
2
T37-6 Yellow
Powdered iron core
3
BS170
TO-92 plastic N MOSFET
1
T100-2 Red
Powdered iron core
1
4 dig LED
4 digit multiplexed display module, hi eff
4
6mmx13mm tack
Push button switch
2
10 uhy rfc
Brown, black, black, gold
6
DP3T slide switch
2
2.2 uhy RFC
Red,red,gold,glod
2
Stereo jacks
1
Super bright
LED clear
4
Knobs
5
4.9152 MHz
Crystals HU-49US
1
Brass shaft adapter
1
Power jack
2.5 mm pin
1
Red filter
1
BNC jack
1
PC board
2
Binding posts
4
1/4” 4-40 screw
#30, #28, #24
3
1 Red, 1 Black
3
Sets of vari-cap mounting hardware
4
#4 lock washers
Magnet wire, #24 hook up wire
These parts are premounted
1
22 p
0805 NPO chip resistor
1
AD9834BRUZ
DDS
4
0.01 ufd
0805 X7R chip capacitor
1
50.00 MHz clk
Clock oscillator
1
0.1 ufd
0805 X7R chip capacitor
1
10 uhy
1206 Choke inductor
1
270 ohms
0805 chip resistor
1
815C35UA
3.5V low drop out regulator
1
3.9 K
0805 chip resistor
Parts placement overview.
Print this page out for handy reference while building. SMT parts are preassembled.
4
Construction hints:
1. Presort the parts into types like resistors, capacitors of different types and values. This will save you time
looking for a particular part later.
2. Some the the yellow, monolithic caps may be supplied with the leads formed for 0.2” lead spacing, while
all the holes on this board are designed for 0.1” lead spacing. It is a simple matter to remove the kink
from the leads with your needle nose pliers to the part will fit into the holes. This may also be true of
some of the ceramic disk capacitors. While the leads are not kinked, the come out of the coating at a
slight angle and can be straightened out so they fit the holes better. This only takes a few seconds to do
and make for a much cleaner looking assembly.
3. Try to make sure the parts sit flush to the board and don't stand up in the air. This is done by slightly
kinking the leads over after you put them in the holes so they don't fall out when you flip the board over
to solder.
4. Once you solder the leads, clip them reasonably flush to the solder pad. Not clipping the leads very short
can lead to them bending over and shorting to things they shouldn't touch.
5. Good soldering skills are paramount to having this or any other kit work properly when you first turn it on.
Nearly all problems with a non-working kit can be tracked down to soldering issues.
6. Proper soldering techniques: Don't use a low wattage iron! 25 to 35 watts is good. You want to be able to
heat a junction quickly. Low wattage irons can't do this and leads to cold solder joints or the solder only
sticking to the part lead and not to the solder pad on the board. You should place the tip of your iron at
the junction of the part lead and solder pad on the board. Then flow the solder in from the opposite side
from the iron. If the junction is hot enough, the solder will flow around the lead and into the hole of the
solder pad. Don't use too much solder! This is a common mistake. You only need to fill the hole, not
make a big pool of solder. Using 0.02” solder instead of the more common 0.032” allows for better
control over how much solder you use. Clean the tip of the iron frequently, but make sure to put some
solder on it if you leave it in the holder for a while. This will keep the tip from tarnishing and become next
to useless. This is very important for iron plated tips.
The photo below illustrates how a well assembled board should look like when it is done:
Okay, now you can start building !
5
Group 1 assembly, Microprocessor and display:
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R42, R44, R46 – 1 K (BRN/BLK/RED/GLD)
R16 to R23 and R43, R45, R47, R53 - 2.2K (RED/RED/RED/GLD)
R24, R52 – 22 K (RED/RED/ORG/GLD) – be careful not to mix up the 2.2 K and 22 K !
R25 to R27 – 4.7 K (YEL/VOL/RED/GLD)
R28, R29, R40, R41 - 270 ohms (RED/VOL/BRN/GLD)
R37, 100 K (BRN/BLK/YEL/GLD)
L4, L5 – 2.2 uHy (RED, RED, GOLD, GOLD)
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C48, C50, C51, C33, C55 - 0.1 ufd (104, mono, yellow)
C49, C52, C53 0.001 ufd (102, Disk, tan)
C45, C46 – 5 pfd or 4.7 pfd (5, 4.7 Disk, tan)
C42, C44 – 47 pfd (47, Disk, tan)
C43, C47 – 100 pfd (101, Disk, tan)
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C30, C24 - 100 ufd / 16V (or 25V) Long lead is plus. Bend leads at right angle to part and lay part flat to board along
extended outline. (You will do this with all the other electrolytic caps on the board too)
C35 10 ufd/16V (or 25V)
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28 pin dip socket at U7 When installing sockets, make sure all the pins are sticking out the holes in the board before
soldering. If one or more pins happens to fold over under the socket as you insert it, it will be very difficult to remove
the socket to fix this once you start soldering pins! Also make sure the notch is facing the right way.
14 pin dip socket at U8
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LED display module. This will only go in one way due to the missing pins on the display and corresponding missing
holes on board. Space the display slightly from board so that the pins only stick out 1/32” from bottom of board.
Solder two corner pins first, then double check to make sure the display is evenly spaced from the board and not
tilted. Re-heating one pin will allow you to make adjustments.
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S1, S2, S3, S4 - Four (4) TACT switches. These have the long actuators.
Phones and Paddle stereo phone jacks. A little side pressure is needed to get the front edge of the jack to be
parallel to the front edge of the board.
DP3T slide switch. (ON/OFF) – make sure switch is flush and square to the board before soldering more than one
lead or mounting tab.
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6
U5, 78L05. Read part number carefully so it isn't mixed up with the other parts in the same T0-92 package. Make
sure flat side of part package lines up with flat side of part outline on the board.
D5, 1N5817 This is the diode in the black body package. Observe polarity, white line on package faces line on part
outline.
Modification:
Due to an error on the circuit board layout, a jumper needs to be added to the bottom of the board at the display
to connect one of the segment leads to the correct pad, as shown below: The jumper will connect the two center
pins on the bottom row of pins of the display. Use a resistor or capacitor lead clipping for the jumper wire.
Group 1 smoke test:
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7
Install the ATMEGA48 microprocessor chip into the U7 socket.
Connect a 9 to 12 volt power supply to the power input pads next to the on/off switch. A 9 volt radio battery would
be adequate for this test, but make sure its a fresh one.
Apply power to the board and turn on power switch if it is not already on.
The LED display should light up with four “8”s for a second. This is the display test. Then the display should display
“40” for another couple of seconds (indicating the band), then 030.0 (this is the frequency)
Clicking closed the Tune UP or Tune DN switches should make the display increment or decrement.
Clicking the RIT switch should make the left most decimal point on the display light up.
The DDS chip should also be working at this point. This can be tested with a frequency counter connected to the
R39/C41 junction at U6 (pin 20,upper right hand corner of the chip) or general coverage receiver tuned to about
11.9452 MHz (+/- 1 kHz) with a short pick up lead for an antenna placed near the DDS chip (U6)
Group 2 Assembly, receiver section:
R15
10 ohm
BRN/BLK/BLK
C3
4.7 p or 5p
NPO, DISK
BROWN
R1
51 ohm
GRN/BRN/BLK
C4, C27
22 p
NPO, DISK
BROWN
R36
270 ohm
RED/VOL/BRN
C7,8,9,10,11,13,14 100 p (101)
NPO, DISK
BROWN
R3
470 ohm
YEL/VOL/BRN
C79
150 p (151)
C0G, mono
yellow
R9, R12
2.2 K
RED/RED/RED
C21
470 p (471)
DISK
BROWN
R4, R5
10 K
BRN/BLK/ORG
C77
.001 u (102)
DISK
BROWN
R8
22K
RED/RED/ORG
C22, C23
0.01 u (103)
FILM
GREEN
R35
47 K
YEL/VOL/ORG
C5,6,12,15,19, 20
0.1 u (104)
MONO
YELLOW
R34
100 K
BRN/BLK/YEL
C25, 26, 28, 32,78
0.1 u (104)
MONO
YELLOW
R10, R13
220 K
RED/RED/YEL
C34
0.47 ufd / 50V
LAY FLAT
ELECTRO
R6, R7
470 K
YEL/VOL/YEL
C31
10 u/16V or 25V LAY FLAT
ELECTRO
R2,R11, R14
1 MEG
BRN/BLK/GRN
C29
100 u /16V
LAY FLAT
ELECTRO
L2,L3
10 uHy
BRN/BLK/BLK/GLD
Q2, Q5
2N7000
MOSFET
TO-92
D1, D2, D6
Glass diode
1N4148
Q3, Q4
2N3904
NPN
TO-92
C17/C18
Not used
Q10
2N3819
N-JFET
TO-92
NOTE: Some kits may have been supplied with green film caps C22 and C23 too tall to allow the board to mount correctly in the top of the
case. If these caps are about 1/2” tall, they will need to be mounted on the bottom of the board and laid down parallel to the board, but
spaced so they clear part leads under them.
L2/L3 look like resistors, but the body is a little shorter and fatter than a resistor. Do not mix up with 10 ohm resistor. Also, be careful not to
mix up 51 ohm resistor with 1 MEG, as colors used are the same, just in a different order.
8
X1,2,3,4,5
Crystals
Tack solder case to solder pads next to crystal case for X1 to X4
C16
30 p trimmer (Green)
Make sure flat side of trimmer faces line on outline. Mount on bottom side of board for
easier access once board is wired into cabinet.
U1,2,3,4
8 pin sockets
Make sure all the pins come through the board holes! Note pin 1 direction for U3 and U4,
they face “down”.
V1
50 K variable resistor
Clip off mounting tabs from frame. (board holes are too small for tabs to go into). Solder
side of frame to pads for mounting tabs.
The following parts
mount on Bottom of board
C1/2
Poly-varicap
Mounts on bottom of board. Secure with short screws (If you have some nylon washers
with the hardware, these used to be used to space the cap from the board, but are no
longer needed and can be discarded.)
L1
T37-2 (red core)
40 turns, 24” of # 30 wire (mount bottom side of board)
T1
T37-2 (red core)
40 turns (#30) secondary, 5 turns primary see below for winding details
T1 winding: Wind with # 30 wire. T1 must be wound in a specific way so that the “hot” end
of each winding will end up on the same side of the core and line up with the proper holes
in the board. Wind the core in a counter clockwise direction, passing the wire down into the
hole from the top side of the core as you hold it. At the end of 40 turns, make a 1” loop and
continue winding five (5) more turns. When your finished winding, snip the loop to form the
two winding, the secondary 40 turn winding and the 5 turn link winding.
The pads for T1 are labeled like this on the bottom of the board:
G o o S (secondary) 40 turn winding
G o o L (Link) 5 turn winding.
If the toroid was wound correctly as shown in the diagram, the start of the 40 turn winding will line up with the pad labeled “S”
and and the start of the 5 turn link winding will line up with the pad labeled “L”. The pads labeled “G” are the ground end of
the windings. If not wound correctly, the windings will line up properly only when the core is at right angles to the outline on
the board. This isn't a big deal, so long as the windings wind up in the proper holes.
Group 2 modifications:
These modifications eliminate display multiplexing noise from the receiver audio.
1.
Install 0.1 ufd mono cap between pins 4 and 5 of U2. The leads of this cap go into the outer most holes of the C17
and C18 locations as shown below:
2.
Install a 470 pfd disk cap (471) between pins 3 and 4 of U3 on bottom of board as shown below:
On the schematic, the new .1 ufd cap installed across pins 4 and 5 of U2 is labeled C18 and the new 470 pfd cap added is
labeled C17, reusing the numbers these caps replaced.
9
Group 2 smoke test:
Install U1 and U2 (SA612A) into sockets
Install U3, LM358 NOTE : U3 and U4 pin 1 faces “down”, the opposite direction of U1 and U2
Install U4, LM386
The receiver section is now done and should now be functional. Give the BFO trimmer (C16) about a ¼ turn from its factory
setting. If you look closely in the trimmer hole, you will see an arrow at one end of the screwdriver slot. When the arrow
points towards the flat side of the body, it is a maximum capacitance. When it points to the round end opposite the flat end, it
is at minimum. Using leads connected to the BNC connector, you can tack these wires across R1 in order to connect up an
antenna (make the connections on the bottom of the board). The end of R1 near Q2 is the signal side of the resistor. Apply
power to the board and you will be receiving in the 40 meter band. Adjust the Rx tuning cap (C1/2) for best band noise or
signal. The peak should occur near full counterclockwise rotation. Plugging in a paddle to the paddle jack and then operating
the paddle should result in hearing the side tone sending dits and dahs. The MENU function switch annunciations can now
also be heard.
DDS frequency calibration and precise BFO setting adjustment:
If you have an accurate frequency counter, the DDS frequency can be calibrated. Without calibration, the operating frequency
maybe off as much as +/- 200 or 300 Hz on the 20 meter band and to lesser extent on the lower bands. This is due to
variations in the reference clock oscillator for the DDS chip. Calibration is done at 10.000,000 MHz, so it could be possible to
zero beat WWV, but it is better left alone if an accurate frequency counter is not available. It is also possible to tweak the IF
offset frequency so that it is centered in the passband of the crystal filter. This adjustment is done with the aid of an
Oscilloscope, which could be a virtual one running on PC, as all you need to see is audio frequencies. The IF offset adjust
mode is also used to set the BFO trimmer to match the side tone of the rig and this can be done by ear.
NOTE: If you do not have the equipment to do the frequency and offset calibration, these steps may be skipped, leaving the
default values in place. You will however need to “click through” to the BFO setting part of the calibration to set the BFO
trimmer cap. This is done by first entering the calibration mode as described below and clicking the MENU switch once to get
to the Offset and BFO adjustment step.
Entering Calibration modes:
While holding the DOT paddle and MENU switch closed, turn power on to the board. The LED display will read [CAL.r].
Reference frequency calibration:
A frequency counter connected to the TP1 test point near the DDS chip will now read about 10 MHz. Use the Tune up and
Tune down switches to adjust the frequency to be exactly 10.000,000 MHz. Once this is done, store by clicking the KEYER
switch. Or you can skip this adjustment by clicking the KEYER switch. This will store the default values and advance to the
offset adjustment.
Beating to WWV
Zero beating to WWV is very hard to do accurately by ear. For one thing, the audio response of your receiver probably
doesn't go down to 0 Hz, which it would have to do to get an exact zero beat. If you have a PC with a PSK31 program, the
best way to do this would be to set the receiver for CW reception and produce an audio beat note with the WWV carrier of
say around 1 kHz. Using the PSK31 program to look at the audio spectrum of the receiver, adjust the beat note produced by
the DDS to exactly match the carrier on the PSK waterfall screen.
IF offset adjust and BFO trimmer set:
Once the MENU switch has been clicked, the LED display will now read [CAL.o]. Connect an Oscilloscope to Pin 7 of U3.
You will see the audio product detector beat note on this pin. If you do not have an Oscilloscope, do not make any
adjustments to the IF offset frequency and just go do the BFO adjustment.
Tune through the pass band of the crystal filter using the tuning switches. You will likely see the amplitude of the signal peak
a little at the edge of the pass band, just before the amplitude rolls of sharply. Tune to one end of the pass band, the point the
amplitude of the signal starts to roll off. Count how many clicks of the tuning switch it takes to get to the other end of the pass
band. Divide that number by 2 and tune back up or down depending on which way you went initially by that number of clicks
to center the frequency in the pass band of the filter.
10
BFO adjustment:
Plug headphones into phones jack and you will hear the side tone and BFO beat note. Adjust the volume control until they
have about the same volume. Adjust the BFO trimmer until both tones are the same. The tones will wobble when they get
close to being equal and seem to merge when they are. This can also be seen on an Oscilloscope. Once you match the
tones, store the adjusted IF offset or leave the default values in place by clicking the MENU switch The rig will now reset.
Group 3 assembly: Transmitter section.
NOTE: Leads may need to be reformed for Q7
to Q9 to fit properly on board. Leads for C54
may also need to be bent inwards to fit holes.
D7
1N4756A
Glass diode, large
C54
0.01 ufd (103)
Film, green
C57, 58, 59
0.1 ufd (104)
MONO, Yellow
C56
330 ufd/16V or 25V Electro lay flat
Q1
2N7000
TO-92
Q7,8,9
BS170
TO-92
Q6
FQPF7P06
TO-220
DO NOT
MOUNT L7 YET
Do pretests first
L7
8 T on FT37-43
8” #28 black core
If C54 is 1/2” long, mount on bottom of board.
Pretests:
Before installing L7, we need to make a few tests first.
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11
Install U8, 74HC02
Put rig in straight key mode by applying power with dash paddle closed or use straight key. If using
paddle, dot paddle will now key the transmitter.
Measure the voltage (to ground) on pins 1 and 13 of U8. They should read 0 volts.
Key the transmitter and measure the voltage (to ground) on the L7 pad to the right, next to C57.
The voltage should be about the same as the supply voltage to the board. If not, check the
connections and proper values of R34 and R35. Also check Q5.
With the transmitter keyed, check the voltage on pins 1 and 13 of U8 again. These should now read
about 2.5 volts. Since these pins now have a square wave at the transmitter frequency on them,
exactly how a DVM responds to this signal may depend on the particular DVM used.
If all these tests are OK, it is now safe to install L7.
Group 4, low pass filters:
L8 to L13 mount on bottom of board. Coil outline is shown on bottom of board.
R30
1K (BRN/BLK/RED)
R31
10 K (BRN/BLK/ORG)
R32
22 K (RED/RED/ORG)
C76
0.1 ufd (104, mono)
C68,C71
150 pfd (151, mono)
C67,C64
220 pfd (221, mono)
C69,C63,C60
330 pfd (331, mono)
C65
560 pfd (561, mono)
C61
680 pfd (681, mono)
C62
68 pfd (68, disk)
C66
47 pfd (47, disk)
C70
22 pfd (22, disk)
Low pass filter
Coils mount from bottom
Of board!
L8
17 turns on T37-2
Red core 10” #28
L9
19 turns on T37-2
Red core 10” #28
L10 (labeled L12 on
13 turns on T37-2
Red core 8” #28
L11
15 turns on T37-2
Red core 8” #28
L12
14 turns on T37-6
Yellow core 8” #28
L13
18 turns on T37-6
Yellow core 10” #28
S5, S6, S7
DP3T slide switch
(a cap marked 680 is 68p, not
680 pfd!)
bottom of board)
Be sure to count the turns on L8 to L13 properly! Count the turns on the inside of the core, not the outside.
Remember, one turn is each time the wire passes through the center of the core. Having just one extra turn will reduce power
output! Also, wind the wire snug to the core. The spacing of the turns will have to be adjusted slightly to produce optimum
power output. If the core is wound too loosely, it will be difficult to make these adjustments and they will not stay in position.
Initially, space the turns evenly around the core. Finally, when the coil is soldered to the board, pull it snug to the bottom of
the board and make sure the wire ends are properly tined. Tinning of the magnet wire is best done before the wire is placed
in the board.
12
Group 5, SWR bridge and balanced line tuner:
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R48, 470 ohm (YEL/VOL/BRN)
R49, R50, R51 - 51 ohm, 2 watt (GRN/BRN/BLK)
D3 – 1N4148, small glass diode. Note polarity.
D4 – clear LED – Align flat side of LED with flat on part outline. Long lead goes into hole opposite the flat. Space
bottom of LED 5/16” from top of circuit board.
S8 - DP3T slide switch
S9 – DP3T slide switch – this mounts above T3. Cut pins flush to board after soldering.
T2 – Black FT43-37 core. Use # 28 wire and wind 25 turns as secondary and 5 turn primary in middle between ends
of the secondary turns. Secondary ends go to into the two outside holes and the primary goes into the two middle
holes.
C72/73 and C74/75 Poly-variable capacitors. Mount on bottom of board. Adjust the trimmers on the bottom of
C74/75 to be fully meshed. (so that they look like a half moon)
T3 mounts on bottom of board, under S9. Coil outline and wire labels are on bottom of board.
Winding T3:
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13
Cut a 24” (2 foot) length of the # 24 wire.
Wind 12 turns on the T100-2 core (this is the large red core)
Start the winding of the core by passing the starting end of the wire into the hole from the bottom of core. Wind the
rest of the turns in a counter clock wise direction, passing the long end of the wire down into the core from the top.
Winding the core in this fashion will make the ends of the wire more or less line up with the staggered holes in the
board. Try to wind the wire fairly flat to sides of the core. Space the turns so that they cover about ½ of the core.
See illustration next page.
Pull the 6th turn on the outside of the core (counting from the left hand starting end) slightly away from the middle,
outside edge of the core.
Scrape away the insulation on the wire of this 6th turn, near the middle of the core.
Cut a 2” length of the # 24 wire and tin one end.
Attach this wire to the 6 th turn on the core. Make a small, half loop on the end of the wire and lightly crimp to wire on
core, then solder.
Cut a 18” length of the # 24 wire and wind 6 turns inter-weaved between the first winding and centered around the
tap you just made, so there are 3 turns on either side of the tap. It is easiest the start the winding of these turns from
the center tap of the first winding.
Now cut a 8” length of the # 24 wire and wind 1 turns on either side of the tap, for a total of 2 turns. This winding will
also be inter-weaved between the other two windings.
Push the windings together so they are close to each other and not spaced around the core.
Before mounting T3 to the board, solder in the wires which will connect to the binding posts into the holes labeled
“BP”. (4.5” long) These wire will pass through the center of the core. If the wires are not installed now, it is difficult to
do once T3 is mounted in place.
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The core is mounted to the bottom of the board and the wires are soldered from the top. Suspend the core slightly
off the bottom of the board so that the wires do not touch the ends of the switch mounted above it. The thick magnet
wire can be difficult to tin properly, so verify connections have been made with an ohm meter.
Illustration 1: Primay winding of T3
with center tap
14
T3 with HI-Z and LOW-Z
winding
Final tests:
The board is now complete and the only thing left to test is the transmitter. Connect the BNC jack to the COAX terminals on
the board by S6. Now connect a watt meter and dummy load to the jack. Make sure both BAND switches are set to the same
band, you might as well start with 40 meters. Set the Tune / Operate switch to the operate position and the COAX / BLT
switch to the coax position. Apply power to the board and send some dots. There should be some power output showing on
the watt meter. If not, remove power and start looking for missing solder connections, that the insulation on the toroid coils
has been soldered through and that both band switches are in the same position. If you see power output, go on and check
the other two bands.
Power output
Power output is influenced by both power supply voltage and the way in which the turns on the transmitter low pass filter coils
are spaced around the core. To measure full power output, put the rig in straight key mode or use “Tune” mode. With a 12.0
volt supply, power output should be close to 5 watts on all bands, with the possible exception of 20 meters, which seems to
be running more like 4.5 watts on average. If power output is higher than 5 watts, move some of the turns on L8, L10 or L12
(depending on the band) closer together and recheck the power output. Repeat if needed to get close to 5 watts output. If
power out is less than 5 watts, try making the spacing of the turns more evenly spaced around the core. If power output is
significantly lower (or higher) than it should be, double check the number of turns on the coils. Remember, a turn is each time
the wire passes through the center of the core. Having one extra turn is common, as many forget to count the first turn when
the wire is initially passed through the center of the core. This can have a significant affect on the power output.
Mounting the board in the cabinet and final wiring:
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15
Tape the red acetate filter to the inside of the led window.
Slide the board into the top piece of the cabinet at an angle with the phone jacks at the front of the board down. To
ease mounting, place all slide switches to the center position. Be careful not to bend the SWR led.
Center the phone/paddle jacks in the chassis holes, and secure the board with the 4-40 x 1/4” screws and lock
washers.
Mount the two binding posts (washer, nut, lug, nut), DPDT toggle switch, Coax jack and external power jack to the
rear of the cabinet.
Wire up the binding posts, switch and coax jack as shown in the diagram below. Make the wires as short and as
direct as possible. The wires going from the coax jack to the board should be routed along the side of the cabinet
and behind the transmitter LPF toroids and connect to the pads labeled Coax and G next to S6.
It does not matter which wire from T3 (BP pads) on the board goes to which binding post, but if the wire from the
pad towards the center of the board goes to the black post, the wires will not cross over each other and help with
the balance.
Twist two 8” lengths of hook up wire together.
Solder to external power jack
Solder the other end to the EXT and GND pads next to the On/Off switch
The wire for connecting to the power jack to the board should be routed along the outside edge of the board.
A photo showing the rear panel wiring is on the next page.
Photo of back panel wiring
(This photo is from the original PFR-3, which had the connections to the BNC jack in a different place, so where it is now [just
below the binding posts] isn't shown)
Once the wiring from the board to the rear panel is completed it is still possible to remove the board from the cabinet but it is
a little tricky to do. Remove the mounting screws and gently push the board towards the rear of the case to free the phone
jacks from the holes in the front of the case. Then gently angle the board up and out.
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Attach the nylon spacers to the tuning caps with the screw and 2.5mm lock washer. A small drop of super glue into
the screw hole on the tuning cap will help keep the screw from coming loose. (You may want to wait until you are
sure you will not have to remove the board from the cabinet for some reason before gluing the screw in place)
Put a small piece of cellophane tape over the shaft of the volume control. Now push the brass knob sleeve all the
way down onto the volume control and secure the knob with the set screw. (Personally, I prefer not to use a knob on
the volume control, KD1JV)
Place the three knobs on the tuning caps. Set the knob as low as it can go without rubbing against the cabinet
Battery holder mounting:
Mount battery holder to bottom of cabinet as shown below. The holders are attached to the bottom side of the cabinet with
double sided tape, which is already attached to the bottom of the holders. Make sure you identify the front of the cabinet
piece correctly. Leave a small space between the sides of the battery holders as when the batteries are installed it will billow
out the sides a little. Connect wires to the battery holder terminals as shown the diagram below. Be quick about soldering the
wires, as the plastic will melt if you leave the iron on too long. Wire the [+] terminal to pad labeled “BAT” next to power switch
and the [-] terminal to the pad labeled “GND”
16
Operation:
Power supply:
The PFR-3A rig should be powered by no more than about 12 volts and no less then 8 volts. Maximum supply current at full
transmitter output is typically less than 800 ma. If a 13.8 volt bench supply is used to power the rig, two silicon rectifier diodes
should be added in series with the positive supply lead to drop the voltage down closer to 12 volts. This will ensure the rig
does not put out more than about 5 watts. 5 watt output at 12 volts was chosen as this is the typical voltage a gel-cell battery
settles down to after it has been removed from its charger. Below 7 volts, the 5 volt regulator for the receiver will start to loose
regulation. Since transmit power output is dependent on supply voltage, a variable supply is a handy way to adjust the power
output level. At the minimum supply voltage of 8 volts, the transmitter will deliver about 2 watts output. Transmitter current will
also be reduced at lower supply voltages, extending battery life.
Power switch:
The power switch has three positions. OFF, Internal (battery) power and External power.
When the rig is first turned on, the display will show all “8”s for a second. This is the segment display test. Then the display
will indicate the currently selected band , “20”, “30” or “40”. The band numbers will be displayed for a couple of seconds, then
the display will change to show the operating frequency. Since only four digits are available, only the 100 kHz to 100 Hz digits
are displayed. MHz digits are implied by the currently selected band. The initial operating frequencies loaded when the rig is
powered on or the band is changed are 7.030,000 MHz for 40 meters, 10.110,000 MHz for 30 meters and 14.060,000 MHz
for 20 meters.
Power save mode:
After about 5 minutes of no switch activity the rig will go into a power save mode by blanking the display and the processor is
put to sleep. The decimal point will stay on to indicate that the rig still has power applied. This will reduce the supply current
from about 47 ma to 34 ma. Not a huge current savings, but if the rig is being run on batteries every ma counts. The rig will
“wake up” if any switch (other than Band) or the paddle is used.
Selecting operating band:
Two slide switches are used to select the operating band. Both switches MUST be in the same band position for proper
operation. The band switch located near the top, center of the cabinet tells the processor which band you want to use and will
indicate the selected band on the display for a second when the band is changed or on power up, as noted above. The
switch located near the top, left of the cabinet is used to connect the output of the low pass filter to the antenna. If the two
band switches are not in sync, there will be no signals in the receiver and the transmitter might be damaged if you transmit at
this time. If you change bands and then return to a previously used band, the frequency the rig was tuned to on that band will
be restored. This feature could be handy if your jumping between bands in a contest. Operating frequencies are lost when
power is turn off and the rig will load the default frequencies again on power up.
After you change bands, you must re-peak the receiver input with the Rx peak control.
Tuning:
Tuning is done with two push button switches. These switches are operated best by “clicking” them to the side, rather then
pushing straight down. Tuning steps are in 50 Hz increments. A momentary click of the switch will change the frequency by
50 Hz. Since the display only has 100 Hz resolution, it will take two clicks of the switch to see a change of frequency on the
display. Holding one of the tuning switches closed for longer than about one (1) second will start an auto tune mode, where
the frequency will change in 100 Hz steps at a rate of about 10 steps per second, so long as the switch is held closed.
When the switch is released, normal 50 Hz “one click” tuning is restored.
Note: If you are in the fast tuning mode and quickly change tuning directions, the tuning may continue the direction that it was
in. This is because there is a slight delay between releasing the switch and the processor detecting that a different switch has
been closed.
Tuning limits:
Tuning is restricted to be within the currently selected ham band. This is to prevent out of band transmission. Full band
coverage is available. 7.000,000 to 7.300,000 on 40, 10.100,000 to 10.150,000 on 30 and 14.000,000 to 14.350,000 on 20.
Even though you can tune into the phone band, SSB signals will not be intelligible due to narrow CW filter.
17
RIT (receiver incremental tuning)
Clicking the RIT switch will activate RIT. The left most decimal point on the display will light when you are in RIT mode. When
in RIT mode, the receive frequency is changed by the tuning switches and the transmit frequency stays were it was when RIT
was activated. Clicking the RIT switch again will exit RIT mode and restore the original receive frequency. If RIT is on when
the band is changed RIT will be automatically turned off.
DFE mode (direct frequency entry)
This mode allows you to go directly to a specific frequency by entering it in with the paddle. Clicking and holding closed the
RIT switch for longer than one (1) second will activate this mode. The display will change to display [- - -.-] when DFE mode
is enabled. Enter the frequency you wish to go to, starting with the 100 kHz digit and finishing with the 100 Hz digit. As each
digit is entered, it will be shown on the display and shift from right to left as additional digits are entered. If a number is not
recognized, a “?” will be sent by the side tone. Once the 100 Hz digit is entered, the rig will re-tune to that frequency provide
it is within the normal tuning limits of the current band. If it outside the band, the frequency at which the rig was tuned to when
DFE was enabled will be restored and DFE mode exited. If you make a mistake or wish to exit the DFE mode at anytime
before the 100 Hz digit is entered, you can escape by clicking any of the switches.
Note: DFE mode is not available in straight key mode or if RIT is on.
MENU switch (Keyer functions) :
The MENU switch is used to access various keyer functions. Which function is selected is determined by how long the switch
is held closed. Keyer functions are selected in this order: send message, change keyer speed, TUNE mode, enter messages
and select iambic A or B mode of operation. Note: When in straight key mode, none of the MENU switch functions are
available, with the exception of sending keyer message 1, assuming a message is already stored in that location.
Sending a Message:
Two, 63 character (including word spaces) Morse messages can be stored in memory. One of these messages can be sent
by first clicking and releasing the KEYER switch and then tapping the DOT paddle to send message one, or tapping the
DASH paddle to send message two. This must be done within 1 second of releasing the switch or the change code speed
mode will be activated. Once a message has started sending, it can be terminated by closing the DOT paddle. If a character
is being sent at the time of dot or dash closure, it must be held closed until that character has finished being sent.
When in straight key mode, only message 1 is available, as the DASH input is always grounded by the straight key plug.
Changing keyer code speed:
If sending a message has not been selected using the paddle after clicking and releasing the MENU switch, speed change
mode will be activated. The current code speed is shown on the display as [C xx], where xx is the current speed. Keyer
speed is changed by closing either the DOT paddle to increase speed or closing the DASH paddle to decrease speed. The
selected speed is shown on the display. Once the desired speed is indicated on the display, release the paddle and wait
about two (2) second and speed select mode is automatically exited.
Tune Mode:
This mode is used if you have an automatic antenna tuner which needs to see a steady carrier for a few seconds to operate.
For manual tuners, it is easier and less stressful on the PA to simply send a string of dots as you fiddle with the tuner.
To enable tune mode, click and hold close the MENU switch until the letter “T” is annunciated by the side tone and release
the switch. When you then release the MENU switch, the display will blank and a character which resembles a lower case “t”
will appear on the left most digit. The transmitter can now be keyed by closing and holding closed either the dot or dash
paddle. When you wish to return the rig to normal operation, click any of the switches.
Storing a message:
Holding closed the MENU switch for four (4) seconds will active the message entry mode. Release the switch when the letter
“M” is annunciated by the side tone, which occurs after the tune mode letter “T” has been annunciated. The receiver is then
muted and you can now start to enter your message by using the paddle. If you accidentally activate this mode and do not
wish to enter a message, click the MENU switch to abort before touching the paddle. The Letter “X” will be annunciated and
the rig will go back to normal operation. There is no visual indication that message entry mode is active.
Up to 63 characters (including word spaces) may be entered. If you exceed this limit, the letters “EM” will be annunciated by
the side tone and you will have to start again. Note that “ideal” letter and word timing is used to determine letter element
18
groups and word groups. Of these two, the letter timing is most critical. If do not pause long enough before starting a new
letter, a letter space will not be detected. If you pause too long, it will be interpreted as a word space. It may take some
practice to enter a message correctly. I ensure a word space is inserted, it is best to pause somewhat longer than you
normally would between word letter groups.
When you have finished entering the message, click the MENU switch. The message you have entered will be sent by the
side tone so you can check the accuracy of the message. If it sounds good, store it by closing either the DOT or DASH
paddle. DOT will store it into message location 1 and DASH into location 2. If you wish to redo the message, click the KEYER
switch again. “EM” will be annunciated by the side tone and you can now re-enter the message.
Selecting Iambic A or B modes.
Iambic A mode is the default keyer mode. To switch to B mode or back to A mode, hold the MENU switch closed for about
four (4) seconds until the letter A or b appears on the display (b looks like a 6 on the display) then release the switch. The
letter which appears on the display will be the mode the keyer will be set to when you release the switch. The Morse letter “A”
or “B” is also annunciated by the side tone.
The difference between A and B modes:
In A mode, if both paddles are closed at the same time, alternating code elements are sent. If you close the dash paddle first
and then hold both the dash and dot paddle closed, the keyer will send dah-dit-dah-dit-dah so long as the paddles are held
closed. When the paddles are released, the keyer will simply stop sending at the end of the code element which might be
being sent at the time the paddles are released, if any.
In B mode, alternating code elements are also sent when both paddles are closed, but this time an extra and opposite code
element will be tacked on the end of the string when the paddles are released. Therefore, to send a letter such as “K”, you
just have to close the dash paddle first, then close the dot paddle and release both paddles when the dot starts to be sent.
dah-dit-dah will be automatically sent. In A mode to send this same letter you would have to keep the dash paddle closed
until the second dash has started to be sent before releasing the paddles.
In B mode, the “both paddles closed” condition is sensed at the end of the inter-element space. Therefore, to insert an extra
element, both paddles need to be held closed at least until the next to last element you want to send is has started. If the
“both paddles closed” condition is sensed any earlier, it is nearly impossible to send a simple letter such as an “A” or “N” and
not have a “R” or “K” be sent instead. Even so, it is easy to accidentally add an extra element if your not quick to release the
paddles which makes B mode a bit difficult to get the hang of with out a lot of practice, especially at higher code speeds.
Both A and B modes have dot and dash memory while an element is being sent. So, if you tap the dot paddle while a dash is
being sent, the dot will be sent after the dash is finished and vice-a-versa.
Straight key mode:
If a monaural plug is in the paddle jack at power up (the sleeve grounds the dash input pin), the rig will power up in straight
key mode. This allows using either a straight key or external keyer. While in straight key mode, none of the keyer switch
functions will be available. If a message has been previously stored in the keyer memories, only memory location 1 will be
available, (tap the straight key closed with in 1 second of clicking the keyer switch) as this is selected with the dot input pin,
now controlled by the straight key.
Using the SWR bridge and BLT tuner:
Note that S7, S8 and S9 are three position switches but only two positions are used. The two positions to
the left are the same.
TUNE / OPRT SWITCH:
Sliding S7 to the TUNE position switches in the SWR bridge. The LED will now indicate the relative amount of SWR. The
brighter the LED, the higher the SWR is. When the LED is not lit or is very dim indicates 1:1 SWR.
COAX / BLT SWITCH
S8 is used to switch between a direct coax connection to the BNC jack or the BLT (balanced line tuner). The Coax position is
of course used if you are using a resonate, coax feed antenna or an external tuner. The BLT position is used when the built in
tuner is desired and is normally used with ladder line feed antennas, but can also be used for end feed antennas or possibly
matching coax feed antennas which need a little tweaking.
19
Using the BLT:
Note: The handle of the switch on the rear panel should be slanted towards the coax jack when using either a
balanced line on the binding posts or just a coax feed antenna.
Before transmitting, adjust the TUNE and LOAD capacitors for best band noise or signal strength. Now switch from Operate
to Tune mode with S7. Now transmit a string of dits or dahs and fine tune the TUNE and LOAD capacitors so that the SWR
LED gets very dim. This of course, is easier said than done. The tuning is very sharp and if you tune too fast you will never
see the LED get dim. A further complication is the Load and Tune controls are interactive.
First slowly adjust the LOAD until you see even the slightest dimming of the LED. Now adjust the TUNE and see if you can
make it even dimmer. Go back to LOAD and see if this will dim the LED farther. If no farther improvement can be made,
advance the TUNE slightly (try clockwise first) which will make the LED brighter again, then try the LOAD. Working back and
forth a few time between the Tune and Load controls should enable you to make the LED become very dim or go out
completely. In most cases when using a ladder line feed antenna, you will use the HI-Z setting of the BLT. In some cases, you
may only be able to find a match using the Low-Z setting.
Once you find the match, you might want to mark the positions of the controls on the panel using some stick on dots. This will
speed up retuning after switching bands.
Using the BLT with end feed wire antennas or coax.
Switching the handle of the rear panel switch so it faces the binding posts will ground the black balanced line binding post
and connect the Red post to the coax jack. End feed wire antennas can now be connected to the Red binding post and a
counter pose to the Black post. Use the High Z position of S9 if the wire is near a 1/2 wave in length. Use the Low Z position
if the wire is near a ¼ wave or less in length. The Low Z position is also used when using the BLT to match a coax feed
antenna.
Headphone warning:
The PFR-3A has some AGC action to help keep strong stations from being too loud, but even so, if the volume control is
turned all the way up, tuning across a strong station can “blow your ears out”. Therefore, turn the volume down before
scanning the band.
Using a speaker instead of headphones:
The PFR-3A can drive a small speaker directly to reasonable volumes.
Fuses:
There are no fuses built into the rig but it is a good idea to add one. A fuse could prevent damage to your power supply or
even a fire if something should go wrong. For the external supply, use a power cord with an in-line fuse holder and use a 1.5
or 2 amp fuse. Adding a fuse to the battery pack is a bit more of a problem. A 2AG sized fuse holder could be added to the
bottom half of the cabinet just above the battery pack and located so it sits between the power jack and receiver input coils.
Paddle wiring:
The paddle jack uses “standard” wiring:
Tip is Dot
Ring is Dash
Sleeve is ground
There is no paddle sense reverse built into the firmware.
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PFR front panel controls and rear panel connectors.
21
Troubleshooting:
With careful assembly, your PRF-3 kit should work right off. Unfortunately, this is not always the case and some
troubleshooting will be required. This job goes a lot quicker if you have a signal generator, Oscilloscope and frequency
counter, but alas, most of you will only have a DVM to work with.
The most common reason a kit does not work is because of assembly errors, the most common being soldering issues.
Soldering issues include missing solder connections, solder shorts between pads which are not connected together, not
using enough heat in places so solder only sticks to a component lead and does not flow into the solder pad and not properly
tining magnet wire leads so there is no continuity through a coil. Less common but still something to look for is miss-placed
parts. It is often easy to miss-read the color codes on resistors, especially those with similar colors, but in a different order.
The above problems can often be found with a simple but careful visual inspection of the board. It does help to have an idea
of which general area the problem maybe in as to narrow down the search.
Bad parts:
All new, prime parts are supplied with the kit. It is very, very unlikely any were bad prior to installation. Unless the part was
physically damaged during assembly, it is safe to assume the part is good. However, some parts, in particular, the 2N7000
and BS170 MOSFETs can be damaged by static while handling and soldering. Some of the ICs can be damaged if they are
installed backwards in the socket and power applied. However, since the regulators which supply voltage to the ICs have
limited current capability and have over current shut down, it is quite likely the IC will survive being installed backwards.
Troubleshooting steps: Divide and conquer
The best way to find out what doesn't work is to first find out what does work. The first step is to make sure proper power
supply voltages are present. If the output of a regulator is lower than it should be and/or the package is getting hot,
something is dragging the output down. This could be caused by one of the aluminum electrolytic capacitors being installed
backwards, a solder short or an IC plugged in up side down.
The next step is to check the voltages on the IC pins. If one or more of these voltages are off significantly, it may not mean
the IC is bad, but something is affecting the voltage on that pin. Before asking for a replacement part, check the parts
connected to those pins and of course, the soldering in that area.
If you still have a problem, its time to start tracing the signal paths. For the receiver, it is easiest the start with the output and
work towards the input. For the transmitter, start at the input and work towards the output.
Group 1, the processor and display:
There is very little go wrong here. If the processor is getting it's +5 supply, it should work. Although there could be problems
with things connected to the various input and output pins which will affect it's operation. If there is a missing segment or digit
on the display, it is likely there is a missing solder connection or short. The same is true if a paddle or the switches don't work
or there is a “stuck switch” problem.
Group 2, the receiver:
The most common problem here is reversing the link and secondary windings of the T1 coil or not having the wire ends
properly tinned so that there is no connection to the pad. Both of these problems will result in very poor sensitivity of the
receiver.
The audio stages are very easy to test. You should hear some “hiss” when the volume control is turned all the way up and
you should hear the side tone when using the paddles. You should be able to hear 60 cycle hum if you touch pins 4 and 5 of
U2 with your fingers. If you hear the side tone but not any hiss or hum which touching pins 4 and 5 of U2, the mute switch Q4
might be shorted out. If the voltages on pins 3 and 5 of U3 are not correct, C24 might be in backwards or the R7 and R12
values interchanged.
The crystal filter and U2 product detector/ BFO oscillator is tested when using the DDS offset calibration mode. There is little
to go wrong here other than soldering problems.
22
Still no luck getting the rig to work?
We will try to first help you via email. QRPKITS does not handle technical questions directly. Send any technical questions to
Steve KD1JV at steve.kd1jv@gmail.com Sometimes we can nail the problem right off, but often it can be of no real help. We
can't look over your shoulder to see whats going on and we're not psychic! Often, we can't do much more than repeat what
has already been said in the above troubleshooting guide. To be of help we need as much information as possible about the
problem. Simply saying that it does not work is of little use.
If all else fails, a repair service is available for a flat $35.00 fee. If you want the rig to be insured on return shipping, add
another $5.00. DX stations will also have to add extra funds to cover air mail postage. It would be helpful if a short note
explaining what kind of problem your having is included. We will try to repair and return the rig as quickly as possible, but it
could take a few weeks in some cases, depending on other work loads from the day job.
Send the rig with a check or MO for the repair fee to:
Steven Weber, KD1JV
Steve's Electronics (if using UPS)
633 Champlain St
Berlin, NH 03570
There is also a PFR-3 user group on Yahoo.groups. Search for the PFR-3 group to find it and join. Many PFR-3 owners are
already members of this group and is a good source of information and help should you need it.
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IC pin voltage charts: Small deviations from listed voltages acceptable due to DVM and voltage regulator tolerances
IC U1, U2 SA612 mixer
IC U3 LM358 op amp
IC U4 LM386 audio amp
Pin 1
1.4 V
IN
Pin 1
3.0 V
OUT
Pin 1
1.25 V
feedback
Pin 2
1.4 V
IN
Pin 2
3.0 V
- IN
Pin 2
0V
- IN
Pin 3
0V
GND
Pin 3
3.0 V
+ IN
Pin 3
0V
+ IN
Pin 4
5.0 V
OUT
Pin 4
0V
GND
Pin 4
0V
GND
Pin 5
5.0 V
OUT
Pin 5
3.0 V
+ IN
Pin 5
2.9 V
OUT
Pin 6
5.9 V
OSC
Pin 6
3.0 V
- IN
Pin 6
6.0 V
V+
Pin 7
5.4 V
OSC
Pin 7
3.0 V
OUT
Pin 7
3.0 V
Bypass
Pin 8
6.0 V
V+
Pin 8
6.0 V
V+
Pin 8
1.25 V
feedback
Note: LED display driver pin voltage vary with digits displayed so typical voltages not shown
IC U6 MEGA 48 MPU processor
24
Rx
Tx
Pin function
Pin 1
5.0 V
5.0V
reset
Pin 2
5.0 V
5.0 V
DDS CLK
Pin 3
5.0 V
5.0 V
DDS EN
Pin 4
5.0 V
0V
Pin 5
5.0 V
Pin 6
IC U8 74HC02 NOR GATE
Rx
Tx
Pin 1
0V
5V square wave
out
Pin 2
5V
5 V square wave
in
Pin 3
0V
Paddle DOT in
Pin 4
5V
5V
out
0V
Paddle DASH in
Pin 5
0V
0V
in
-------
-------
Digit 3
Pin 6
0V
0V
in
Pin 7
5.0 V
5.0 V
Vcc
Pin 7
0V
0V
GND
Pin 8
0V
0V
GND
Pin 8
0V
3.5V square wave
in
Pin 9
--------
--------
Decimal point
Pin 9
0V
0V
in
Pin 10
-------
---------
“d' segment
Pin 10
5V
5V square wave
out
Pin 11
--------
---------
Digit 1
Pin 11
0V
0V
in
Pin 12
--------
---------
Digit 2
Pin 12
5V
5V square wave
in
Pin 13
--------
---------
Digit 4
Pin 13
0V
5V square wave
out
Pin 14
--------
---------
“e” segment
Pin 15
--------
---------
“f” segment
Pin 16
----------
---------
“b” segment
Pin 17
---------
--------
“g” segment
Pin 18
---------
--------
“a' segment
Pin 19
---------
---------
“e” segment
Pin 20
5.0 V
5.0 V
AVcc
Pin 21
5.0 V
5.0 V
Aref
Pin 22
0V
0V
GND
Pin 23
5.0 V
5.0 V
A/D switch input
Pin 24
2.5/1.5/.22
Same
A/D Band input
Pin 25
0V
5.0 V
MUTE out
Pin 26
0 or 5 V
2.5 V
Side tone out
Pin 27
0V
5.0 V
Tx enable
Pin 28
5 or 0 V
5 or 0 V
DDS Data
in
Pin 14
5.0 V 5.0V
Vcc
Pins 1 and 13 will measure about 2.5 volts with
DVM when transmitting steady carrier.
Schematics:
Receiver / audio
25
CPU, DDS, Tx
26
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