Mobat_AC-500_user
Antenna Tuning Unit
AC500 TS5.210
HF-SSB Automatic Antenna Tuner
1.6-30 MHz, 500 W
photograph TBD
Owner’s Manual
Antenna Tuning Unit
AC500 TS5.210
HF-SSB Automatic Antenna Tuner
1.6-30 MHz, 500 W
Owner’s Manual
Antenna Tuning Unit
AC500 TS5.210
HF-SSB Automatic Antenna Tuner
1.6-30 MHz, 500 W
TABLE OF CONTENTS
Para.
Page
Performance Specification ..........................................................................................................................................iii
Model Complements .................................................................................................................................................... v
Accessories................................................................................................................................................................... v
CHAPTER 1
1.1
1.2
GENERAL DESCRIPTION ..................................................................................................................1-1
FUNCTIONAL AND STRUCTURAL DESCRIPTION ..................................................................1-1
CHAPTER 2
2.1
2.2
DESCRIPTION
INSTALLATION
GENERAL ...............................................................................................................................................2-1
RECOMMENDED EQUIPMENT .......................................................................................................2-1
2.2.1
2.2.2
2.3
Tools...........................................................................................................................................2-1
Accessories .................................................................................................................................2-1
INSTALLATION INSTRUCTIONS ...................................................................................................2-1
2.3.1
Cable Kits ...................................................................................................................................2-1
2.3.2
Installation Instructions ..............................................................................................................2-1
2.3.3
Operational Check ......................................................................................................................2-4
i
TABLE OF CONTENTS (Cont.)
Para.
Page
CHAPTER 3
3.1
THEORY OF OPERATION
FUNCTIONAL DESCRIPTION .......................................................................................................... 3-1
3.1.1
3.1.2
3.2
ATU Function ............................................................................................................................ 3-1
ATU Operation .......................................................................................................................... 3-2
ELECTRICAL DIAGRAMS DESCRIPTION ................................................................................... 3-2
3.2.1
Tuning Sensors Board TS5.281 ................................................................................................. 3-2
3.2.2
Matched Loop Board TS5.282................................................................................................... 3-4
3.2.3
Control Board TS5.283 .............................................................................................................. 3-6
APPENDIX A
ii
DIAGRAMS
PERFORMANCE SPECIFICATIONS
ELECTRICAL
Frequency Range
1.6-30 MHz
Input Power Capability
Not more than 500 W
Input Impedance with matched ATU
50 Ω with VSWR not higher than 1.4
Tuning Time
Programmed: not higher than 5 seconds
From pre-saved frequencies in memory: not higher than 300 msec
RF Tuning Power
3-14 W
Antennas
For frequency range 1.6-30 MHz:
-
19.46 ft (6 m) to 32.43 ft (10 m) whips
-
22.7 ft (7 m) to 97.3 ft (30 m) wire antennas
For frequency range 2-30 MHz:
Power Requirements
13 ft (4m) whip
24 V dc nominal, 2 A
iii
GENERAL
Environmental Conditions
Vibration
MIL-STD-810D Method 514.3 and EIA RS152B
Shock
MIL-STD-810D Method 516.3 and EIA RS152B
Sand & Dust
MIL-STD-810D Method 510.2
Rain
MIL-STD-810D Method 506.2
Salt Fog
MIL-STD-810D Method 509.2
Operating Temperature
-30ºC to +60ºC
Storage Temperature
-40ºC to +85ºC
Humidity
95% @ 20ºC to 85ºC
Dimensions (H x W x L)
TBD" x TBD" x TBD" (? cm x ? cm x ? cm)
Weight
TBD lbs (TBD kg)
Specifications subject to change without notice
iv
MODEL COMPLEMENTS
Model TBD
TBD
Mobile Automatic Antenna Tuner (ATU-AC500) 500 W
TBD
Housing
TBD
Antenna Tuner Board
TBD
ATU Assembly
TBD
RF Coax Cable Kit
TBD
ATU AC500, HF-SSB Automatic Antenna Tuner Owner’s Manual
ACCESSORIES
TBD
RF Cable kit, TBD feet (N Type - UHF)
TBD
RF Cable Kit, TBD feet (N Type - UHF)
v/(vi Blank)
v
CHAPTER 1
DESCRIPTION
1.1
GENERAL DESCRIPTION
The Mobat HF-SSB Automatic Antenna Tuner Unit
(ATU) model AC500 is an antenna matching network
that provides efficient RF power transfer from the radio
system to the antenna.
The ATU handles up to 500 watts Peak Envelope
Power (PEP). It is used for voice and Continuous Wave
(CW) Morse code communications.
A control circuit checks the antenna matching, each
time the channel is changed, and then automatically
switches inductors and capacitors in and out of the
matching network. The tuning data for a given channel
is stored in a memory and kept as long as the ATU is
on. The next time the channel is used, the stored tuning
data for that channel is used, considerably reducing the
tuning time (provided that the VSWR is within the
specified limits).
The ATU AC500 matches the antenna impedance to the
50 Ω output impedance of the radio system, with a
nominal VSWR of not higher than 1.4 in the 1.6 to 30
MHz frequency range.
The AC500 TS5.210 unit comprises the following
components (Figure 1-1):
•
High Voltage Isolator
The ATU is housed in a weatherproof aluminum case
with four M8 bolts, allowing outdoor installation, such
as open roofs. An antenna isolator is located at the top
of the case to isolate the antenna input connection made
of copper strip (see Figure 1-1). Two bolts with M6
nuts secure the case to ground.
•
High Voltage Inductor - TS5.210.820
•
Chassis with High Voltage Vacuum Relays-
•
Matched Loop Board - TS5.282
1.2
•
Sensors Board - TS5.281
•
Control Board - TS5.283
•
RF and Control Input connectors.
FUNCTIONAL AND
STRUCTURAL DESCRIPTION
The AC500 Automatic Antenna Tuner (ATU) operates
in the 1.6 to 30 MHz frequency range at 500 watts peak
envelope power (PEP). The ATU automatically selects
the network component for the antenna matching, thus
eliminating the need for programming, presetting,
manual tuning and adjustment during the installation
and the operations.
TS5.210.001
1-1
Description
TBD
a. General View
TBD
b. Structural View
Figure 1-1. AC500 Views
1-2
CHAPTER 2
INSTALLATION
2.1
GENERAL
The MICOM Radio and AC500 ATU are factory-preset
for proper tuning operation and require no additional
adjustment or programming.
2.2
RECOMMENDED EQUIPMENT
2.3
INSTALLATION INSTRUCTIONS
2.3.1 CABLE KITS
The ATU basic model is supplied with the TBD-Model
No. High Voltage Cable Kit and the TBD-Model No.
RF coax cable kit.
2.2.1 TOOLS
2.3.2 INSTALLATION INSTRUCTIONS
- Nut driver TBD
- Flat blade screwdriver TBD
The antenna and the ATU locations on a base station
are the most critical parts of radio components
installation, since they have a great influence on the
effective radiated power.
- TBD
The installation instructions refer to:
- Nut driver TBD
2.2.2 ACCESSORIES
For base station installations:
TBD
High voltage cable kit
(supplied with the ATU)
TBD
TBD ft cable kit
TBD
TBD ft cable kit
- Antenna Installation
- ATU Installation.
The interconnection between AC500, amplifier PA-500
and MICOM Radio are illustrated in Figure 2-1.
2-1
ANTENNA
INPUT RF
J1
MICOM-RADIO
AMPLIFERS
500 Watt
ANTENNA
J12
22
33
44
ChChange
TUNE
OK
OVER
GND
+24VDC
GND
1
2
3
ATU
TS5. 210
4 CONTROL
5
J2
6
7
8
9
10
Figure 2-1. AC500, PA-500 and MICOM Radio Interconnection
2.3.2.1
Antenna Installation
around the antenna’s location. The number of copper
wires used is not less than 6.
The unit AC500 TS5.210 is intended to provide
transmitter’s operation with the following antennas:
-
Whip antenna height Н=4m (frequency range
2.0-30.0 MHz)
TBD
-
Whip antenna height Н=6m-10m (frequency
range 1.6-30.0 МHz)
Figure 2-2. Whip Antenna - Base Station Location
-
Wire antennas 7-30 m long.
2.3.2.1.1
Whip antennas
Whip antennas (See Figure 2-2) are connected using
an isolated connection protected by a high-voltage
insulator. The insulator is designed to work with high
voltages not less than 10 kV.
Whip antennas are mounted on top of a building or a
base station. The antenna should be located away
from interfering structures, such as other antennas,
metal masts, buildings and metal wires parallel to the
antenna. The radius from these interfering structures
to the AC500 antenna should be about 6-10 m. If the
antenna is installed on top of a building with a nonmetallic roof, the antenna copper wires (with section
area 5-6 sq. mm - AWG-TBD) are to be laid radially
2-2
2.3.2.1.2
Wire antennas
The wire antennas (see Figure 2-3), including L-type
or T-type, are made of copper cables/ropes with
section area not less than 15 sq. mm - AWG-TBD.
The number of wires (“beams”) may vary from 1 to
3. The lower point of the wire antenna is mounted on
an insulated mounting, to avoid any mechanical loads
on the antenna insulator.
Insulators of wire antennas and insulated antenna
mountings should work with high voltages not less
than 10 kV.
Installation
When the antenna is installed at ground surface or on
top of a building with a non-metallic roof, it is required
to lay copper wires (with section area 5-6 sq. mm AWG-TBD) at all area of projection below the antenna.
The number of wires that are connected radially from
the antenna’s ends, should be not less than 6, and the
number of wires connected perpendicularly below the
antenna, should be not less than 1 wire per 2 meters.
The length of every wire should be not less than the
height of antenna’s mast. The insulation resistance of
an antenna-feeder section should be not less than 20
MΩ at normal conditions and not less than 1 MΩ - in
other climatic conditions.
optimum) form an effective ground plane above 7
MHz. Below 7 MHz, the required length gets
unreasonably long; however, more than four radials 30
to 70 feet (9.1 to 21.3 m) long are recommended. A
direct connection to a ground rod driven into the earth,
or a connection to a water pipe of the building, is
required for lightning protection.
Figure 2-4. Practical Ground Using a Metal Building
Figure 2-3. Inverted “L”Wire Antenna
2.3.2.1.3
Antenna Ground Planes
The ground plane provides an RF current return path
for the antenna. For efficient operation, the loss
resistance in the ground path must be small in
comparison to the antenna radiation resistance.
Furthermore, the effective length of the ground path
largely affects the shape of the antenna radiation
pattern. A poor ground will cause an otherwise good
radio to perform poorly.
This section provides a description of a ground plane
and explains its installation. A good ground plane must
be spread out with the antenna located normally in the
center.
A fairly effective ground can be achieved by grounding
to the building structures or metal roof (see Figure 2-4),
provided that the roof pieces are electrically bound
together. Antennas far from earth on insulated
structures require a ground plane (or radial system).
Two or four radials out to a quarter or half wavelength
for each frequency used (3/8 x wavelength is a fair
2.3.2.2
ATU Installation
(See Figure 2-5 and Figure 2-6)
Step 1. Locate the ATU on the top of the building as
near as possible to the whip’s antenna input or to the
lower end of the wire antenna.
Step 2. Place the ATU horizontally with the upper
cover upwards or vertically with the antenna insulator
upwards.
Step 3. Mount the unit using four M8 bolts, on a
surface with a non-flatness less than 1 mm.
Step 4. If the surface is metallic, remove the paint
around the mounting points and connect the surface to
ground as required. Connect the shortest possible
ground lead between the antenna ground plane and
ATU ground terminal. The base station ground, ATU
ground and the antenna ground plane must be bonded
to the earth ground using two M6 nuts and copper wire
with section area of not less than 20 sq. mm - AWGTBD and not more than 0.1 m long.
Step 5. Connect the ATU antenna insulator to the whip
antenna using a copper wire with section area of not
less than 20 sq. mm - AWG-TBD and not more than
0.5 m long.
2-3
Installation
Step 6. If the ATU is installed in an unattended room
and not affected by the weather, connect it to a whip’s
antenna input or to the lower end of the wire antenna,
using a copper wire with a section area of not less than
10-15 sq. mm - AWG-TBD and not more than 2 m
long. In this case, attach between the antenna insulators
and the ATU by insulated support racks less than 50
mm in height and place them into a screening shroud
with section area not less than 100 x 100 mm. The
insulated support racks are designed to work with high
voltages not less than 10 kV.
Step 8. Perform the operational check given in
paragraph 2.3.3.
CAUTION
Do not install the ATU without the
earth ground. The earth ground is
required both for the ATU efficient
operation
and
for
lightning
protection.
Step 7. Route the RF coaxial cable (with 50 Ω
impedance) and the control/power cable between the
ATU and the power amplifier/radio.
Step 8. Connect the RF coaxial cable to the ATU's
INPUT RF connector and to the Power Amplifier
output (see Figure 2-1).
Step 7. Connect the control/power cable to the ATU’s
CONTROL connector and to MICOM-RADIO
connector.
TBD
Figure 2-5. Typical Base Station Installation with
Whip Antenna
Figure 2-6. Typical Base Station Installation using Wire Antenna
2.3.3 OPERATIONAL CHECK
When the system installation is completed, perform the
following operational check (see Figure 2-1):
Step 1. Install an in-line wattmeter between the Power
Amplifier and the ATU.
Step 2. Turn on the Radio and the Power Amplifier.
2-4
Step 3. Whistle into the microphone; observe the
forward and reverse power reading on the wattmeter.
The forward power should be at least three times
greater than the reverse power.
CHAPTER 3
THEORY OF OPERATION
3.1
FUNCTIONAL DESCRIPTION
The ATU AC500 functional diagram is depicted in
Figure 3-1.
La
VSWR 1
SENSOR
Vf1 Vr1
Vf
Vr Ph G
Lb
Ld
ANTENNA
SENSOR
CURRENT
Iant
TUNING
SENSORS
R
Cb
Ca
VOLTAGE
SENSOR
Vant
Ian
Vant
ChChange
TUNE
OK
CONTROL BOARD
OVER
+24VDC
GND
Figure 3-1. ATU AC500 Functional Diagram
3.1.1 ATU FUNCTION
•
The ATU allows for an effective energy transfer
between the radio/power amplifier and the antenna.
This is basically achieved by meeting the following
requirements:
Minimizing the insertion loss of the matching
network.
•
Preventing mismatch losses by presenting
appropriate impedances to the radio power
amplifier and the antenna.
3-1
Theory of Operation
3.1.2 ATU OPERATION
•
The ATU operates in the following modes:
•
Set-up in reset state
•
Standby mode
•
Matched loop tuning
•
Transmission.
Reset state: When setting up in reset state mode, the
controller initialization is performed. In this mode, the
controller sets its ports into reset state upon power
supply turn on. After reset state set-up is completed,
the controller enters standby mode.
Matched loop tuning: Tuning mode starts when 3-5
msec positive "ChChange" control pulse is applied to
the circuit. At the end of "ChChange" pulse, the ATU
controller switches on the tuning sensor using "DD1"
command. This low level signal is received from ATU
through "TUNE" circuit and is sent to the transmitter
that initializes 3-14 W RF signal at the transmitter
output. The transmitter output is transferred to the ATU
input and then to the frequency meter and tuning sensor
TS5.281 inputs.
The frequency meter measures transmitter’s RF signal
frequency and defines the record/recovery channel
number of the matched loop LC cell from the ATU
control board nonvolatile memory. Appropriate LC
elements are switched on, forward and reflected wave
voltages are measured by the tuning sensor and VSWR
is calculated.
If VSWR is less than 1.5 then tuning process signal
"TUNE" is switched off (control signal applied to
"TUNE" circuit is set up to high level) by switching off
RF power at ATU input. "DD1" command is turned off
(tuning sensor is off) by the ATU "OK" low level
signal, that indicates ATU tuning has been completed,
and the controller enters standby mode.
If VSWR is higher than 1.5 then matched loop tuning
process starts using LC elements commutation in
accordance with the tuning algorithm.
Tuning sensor TS5.281 provides error signals as
follows:
•
Ph - error by phase
•
R - error by active resistance
•
G - error by active conductance
3-2
Error by value of forward (Vf) and reflected (Vr)
waves.
These signals define the level and type of the matched
loop disparity by phase, active resistance, active
conductance and VSWR.
The signals received from sensor board TS5.281 are
transferred to control board TS5.283.
If ATU is tuned with an antenna controlled by a
matched loop current and voltage out of limits, then
simultaneously with the low level “OK” signal applied
to “OVER” circuit, a signal is transferred to the
transmitter for signalizing transmitter power reduction
to 200-250 W. At this stage the tuning mode is
completed.
Transmission: The transmission mode starts
immediately after the matched loop tuning has been
completed. Once RF power is received at the ATU
input, the controller starts to control ATU status using
Vf1 forward wave sensor. During this stage, the
controlled forward (Vf1) and reflected (Vr1) waves
level is measured and VSWR1 is calculated.
Additionally, antenna current Iant and antenna input
voltage Vant are measured and the temperature sensor
S1 is controlled.
If VSWR1 is greater than 2, or Iant and Vant are out of
limits, or S1 temperature sensor is triggered, then a low
level signal is transferred from the “OVER” circuit to
the transmitter, signalizing to reduce transmitter power
to 200-250 W. When this stage is completed, the ATU
controller switches to standby mode.
3.2
ELECTRICAL DIAGRAMS
DESCRIPTION
The ATU electrical
Appendix A.
diagrams
are
depicted
3.2.1 TUNING SENSORS BOARD TS5.281
(see Electrical Diagram TS5.281 - TBD)
The Tuning Sensors TS5.281 comprise:
•
Standing wave sensor (SWR1)
•
Standing wave sensor (SWR)
•
Phase sensor
•
Active conductance sensor
•
Active resistance sensor
in
Theory of Operation
•
Matched loop input capacitors group.
3.2.1.2
Standing Wave Sensor (SWR)
The standing wave sensor (SWR1) is used for ATU
operation control when input power is up to 500 W.
The standing wave sensor (SWR) consists of forward
wave and reflected wave sensors.
The standing wave sensor (SWR), phase sensor, active
conductance sensor and active resistance sensor are
used for ATU tuning when input power is between 3-14
W. These sensors are switched on for tuning the ATU
when K4, K12 relays are activated by the "DD1"
circuit.
SWR sensor consists of capacitive voltage divider C27,
C31, C42 capacitors, a current transformer T3 and R21,
R23 resistors and two diode detectors D7, D9. The
SWR sensor operates by the same principle as SWR1
sensor.
The RF voltage is transferred from resistor R41 through
connector J2 to the frequency meter that is located on
the control board TS5.283.
3.2.1.1
The standing wave ratio SWR is calculated using the
following formula:
SWR1 =
Vf + Vr
Vf − Vr
Standing Wave Sensor (SWR1)
The standing wave sensor (SWR1) consists of forward
wave and reflected wave sensors.
SWR1 sensor consists of a capacitive voltage divider
with C3, C4, C7 capacitors, a current transformer T1,
R3, R5 resistors and two diode detectors D1, D3.
When the load is 50 Ω, the capacitor C7 voltage is
equal to the R3, R5 resistors voltages. The R3, R5
resistors voltages are at opposite phase, meaning that
D1 diode input voltages are summed, D3 diode input
voltages are deducted and the resulting total voltage
equals to zero. These voltages are detected by the
diodes and are transferred to the sensor input via Vf1,
Vr1 circuits.
When the load is other than 50 Ω, the C7 capacitor
voltage is not equal to R3, R5 resistors voltages. The
R3, R5 resistors voltages are at opposite phase,
meaning D1 diode input voltages are summed and D3
diode input voltages are deducted but the resulting
voltage in this case, is not equal to zero.
When the load consists of 50 Ω resistive load,
combined with inductive or capacitive component
connected serially or in parallel, the voltage on C7
capacitor is not in-phase to the R3, R5 resistors
voltages, meaning D1 diode input voltages are summed
and D3 diode input voltages are deducted but the
resulting voltage in this case, is not equal to zero.
The signals "Vf1" and "Vr1" are transferred to ADC
circuits in TS5.283 controller. The ADC digital data
serves for standing wave ratio SWR1 calculation based
on following formula:
SWR1 =
3.2.1.3
Phase Sensor
The phase sensor consists of a voltage divider with
C26, C28, R14, R15, L2 components, a current
transformer T2, R12, R16 resistors, two diode detectors
D5, D6 and a balance unit with R11, R13, R18
resistors.
When it is connected to 50 Ω load, the R12, R16
resistors voltages are equal to each other and 90
degrees phase displaced relative to R14, R15 resistors
voltages, meaning that D5, D6 diode input voltages are
equal. The output diode voltages (Ph+, Ph-) are equal
as well.
These voltages are transferred to sensor’s output
connector J1.
When it is connected to a complex load that includes a
reactive component, the R12, R16 resistors voltages are
phase displaced relative to R14, R15 resistors voltages,
with an angle different than 90 degrees. It means that
D5, D6 diode input voltages are not equal and the diode
output voltages are not equal either.
If the reactive component of the load has inductive
characteristics, the output voltage Ph+ is higher than
Ph- output voltage, and if the reactive component has
capacitive characteristics, the output voltage Ph+ is less
than Ph- output voltage.
When it works at frequencies higher than 7 MHz, the
VPh circuit outputs a signal that switches K4 relay to
on. The relay contacts short the R15 resistor, and
therefore the D5, D6 diode voltages are reduced to a
permissible level.
Vf1 + Vr1
Vf1 − Vr1
3-3
Theory of Operation
3.2.1.4
Active Conductance Sensor
The active conductance sensor consists of capacitive
voltage divider C67, C71, C55, a current transformer
T4, resistor R31, two diode detectors D10, D11 and a
balance circuit with R29, R30, R33 resistors.
When it is connected to a 50 Ω load, the voltage on
C55 capacitor is twice higher than the voltage on R31
resistor. These voltages are out of phase, meaning D10,
D11 diode input voltages are equal and output diode
voltages (G+, G-) are equal as well. These voltages are
transferred to the sensor’s outputs.
When it is connected to a load higher than 50 Ω, the
voltage on C55 capacitor increases, and the voltage on
resistor R31 decreases, meaning that the voltage (G+)
increases at D10 diode output and voltage (G-)
decreases at D11 diode output.
When it is connected to a load less than 50 Ω, the
voltage on C55 capacitor decreases and the voltage on
resistor R31 increases, meaning that the voltage (G+)
decreases on D10 diode output and the voltage (G-)
increases at D11 diode output.
When it is connected to a 50 Ω load, with inductive or
capacitive component connected to the load in parallel,
the D10, D11 diode input voltages remain equal and
diode output voltages are equal as well.
3.2.1.5
Active Resistance Sensor
An active resistance sensor consists of capacitive
voltage divider based on C62, C69, C72 capacitors and
a current transformer T5, resistors R37, R38, two diode
detectors D12, D13 and a balance circuit based on R35,
R36, R40 resistors.
When it is connected to a 50 Ω load, the voltage on
C62 capacitor is twice less than the voltage on R37,
R38 resistors and these voltages are out-of phase,
meaning that D12, D13 diode input voltages are equal
and these diodes output voltages (R+, R-) are equal as
well. These voltages are transferred to the sensor’s
output.
When operating with a load higher than 50 Ω, the
voltage on capacitor C62 increases and the voltage on
resistors R37, R38 decreases, meaning that D12 diode
output voltage (R+) increases and D13 diode output
voltage (R-) decreases.
When operating with a load less than 50 Ω, the voltage
on capacitor C62 decreases and the voltage on resistors
R37, R38 increases, meaning that D12 diode output
3-4
voltage (R+) decreases and D13 diode output voltage
(R-) increases.
When operating with a 50 Ω load and inductance or
capacity component serially connected to it, D12, D13
diode input voltages remain equal and the diode output
voltages are equal as well.
3.2.1.6
Matched Loop Input Capacitors Group
This group is formed by a discretely switched set of
capacitors with values changed in a binary order. The
operation of this group of capacitors is described in the
following “Matched Loop” section.
3.2.2 MATCHED LOOP BOARD TS5.282
(See Electrical Diagram TS5.282 - TBD)
The Matched loop board TS5.282 consists of the
following parts:
•
U-shaped loop
•
Antenna current and voltage sensors
•
Filters for interference suppression.
The transformation of antenna-feeder circuit is
provided by a U-shaped circuit formed by a group of
input capacitors, group of input inductances and a
group of input capacitors switched by electromagnetic
relays K1 to K25.
The group of input capacitors on TS5.281 board, is
switched by an electromagnetic relay using commands
"C1"-"C9".
The group of output capacitors is formed by a
discretely switched set of capacitors C8, C14, C20,
C25, C30, C36, with values changed in binary order.
The group of output capacitors is switched by
electromagnetic relays using commands "С11"-С16".
The group of inductances is formed by a discretely
switched set of inductances L19 to L26 and L28. The
group of inductances L19 to L26 has values that are
chosen in binary order.
The group of inductances L19 to L26 is used for tuning
the frequency range of 4.0-30.0 MHz and the precise
tuning range of 1.6-30.0 MHz. The main tuning of the
frequency range 1.5-4.0 MHz, is performed using the
inductances L1 and L2, located in the unit’s case.
The group of inductances L19 to L26 and L28 is
switched by electromagnetic relays using commands
"L1"-L8" and “Ld”.
Theory of Operation
In frequency range 20-30 MHz, if the circuit resonance
frequency (formed by load inductive resistance and
assembly parasite capacity), interferes with transmitter
working frequency, then additional inductance L28 is
connected serially with unit’s output by “Ld” command
using relays K24 and K25.
The relay windings K1 to K25 are grounded by
capacitors for decreasing high frequency effects.
Additionally, HF chokes are connected serially, for
decreasing pulse interference during switching and HF
interference during emission operation.
The ATU power supply voltage of +24 V is fed through
an interference filter using С1, C6, C9, L17, L18
components.
means that the capacitors "С11"-"С16" are switched
serially one-by-one.
Then, if Z1 point, indicating input resistance of the
matched loop, moves to point Z2, that lies at circlecharacteristics of conductance sensor G, it means that
"L1"-"L14" inductances are switched (opened) one-byone. Then, if Z2 point, indicating input resistance of the
matched loop, moves to point Z3 inside the circle of
reflected wave sensor characteristics, it means that the
capacitors "С1"-"С9", are connected serially. That is
compatible with an input resistance of 50 Ω at SWR not
more than 1.3, and the matched loop tuning process
ends.
The matched loop tuning process is depicted in Figure
3-2.
When operating at HF emission, the U-shaped loop
voltage is transferred via capacitors divider С43, С44 to
diode D1 detector. The detected voltage is output at J1
connector and is transferred to the control board
TS5.283 by circuit “Vant”.
The input resistance values are shown in Ra and Xa
coordinates, divided by fields defined using sensors
specifications Ph, R, G. Before the tuning process is
started, groups of input and output capacitors are
disconnected and inductances are shorted.
The HF voltage, that is proportional to U-shaped loop
HF current, is transferred from secondary winding of
T1 transformer to D2 diode detector. The detected
voltage is output at J1 connector and is transferred to
the control board TS5.283.
3.2.2.1
Matched Loop Tuning Process
If Za point, indicating antenna input resistance, moves
by the indicated path in the chart to the Z1 point, it
3-5
Theory of Operation
Za
+Xa
Z2
G=1
G=0
0
R=0
Ra
Ph=1
Z3
Ph=0
Ra
R=1
Z1
Figure 3-2. Tuning Chart
3.2.3 CONTROL BOARD TS5.283
(See Electrical Diagram TS5.283 - TBD and
Figure 3-3)
The control board TS5.283 is used for ATU
operation control.
•
EEPROM
•
Voltage stabilizer.
The micro-controller AT90S8535 is used as Central
Processor Unit (IC U5). The micro-controller
AT90S8535 consists of the following:
The control board comprises the following functional
blocks:
•
Low inherent consumption, 8-channel 10-bit
analog-digital converter
•
Central processor unit (CPU)
•
•
Serial registers
8Kb of in-circuit re-programmable flash memory
(1000 cycles of rewriting)
•
Amplifiers
•
•
512 bytes of EEPROM (100000 cycles of
rewriting)
Circuit of CPU starting after the power is turned
on
•
32 programmable input-output lines
•
Serial Communication Converter UART to RS232
•
Watchdog timer
•
System of internal and external interrupts,
3 timers/counters
•
Programmable UART.
•
Frequency measuring circuit
•
Comparators
3-6
Theory of Operation
Furthermore, the micro-controller has a SLEEP mode
that halts the timing oscillator.
To provide quick set-up of ATU, non-volatile
EEPROM FM24C16-5 (16 Kb) is used to store ATU
settings. It is controlled by a serial bus (SCL, SDA).
Data is received serially from DATA lines and timed
by a clock signal CLK. The data is received by registers
74HC595 (IC U11 to U14). Data transmission from
internal registers IC U11 to U14 to their external
outputs is performed by micro-controller output signals
WR1 to WR4.
Registers U11 to U14 output signals are amplified by
U11 to U14 amplifiers and U15 to U19 (TPIC2701N).
The transistors Q1, Q3, Q5 are used to amplify TUNE,
OVER and AM signals.
The analog signals Vf, Vr, Vf1, Vr1, Iant, Uant received
from setting sensors via filters are transferred to the
analog inputs of the micro-controller. The IC
TL431BID (U7) is used to provide a stable reference
voltage for the analogue-to-digital converter.
The logic levels of Ph, R, G signals are formatted using
the analog signals Ph+, Ph-, R+, R-, G+, G- and the
comparator LM2109D.
As the SLEEP mode is activated for radio frequency
noises lowering, the interrupt circuits are controlled by
the signals ChChange (R34, R30, D4, U4) and Vf1
(R14, C12, U2, R32, R33, R35, R31, C34, U4) and are
used for a stable “wake-up”.
The signal received from overheating sensor SW75 via
the threshold element 74HC14D (U4) enters the microcontroller.
The IC MAX232EWE (U15) converts UART serial
data to RS-232 interface serial data.
The timer T1 converts the frequency-measured signal
to the FREQ data that enters the micro-controller. The
FREQ signal is converted to TTL level by the
transistors Q2 and Q4 and then its frequency is lowered
by divider IC EMP7032SL, to a frequency perceptible
by the micro-controller.
The controller board TS5.283 is fed by 24 V ± 4 V
power supply. To ensure that +5 V voltage conforms
with the value required for controller’s ICs operation,
the stabilizer MC7805B (U3) is used to decrease the
level of radio frequency noise.
3-7
Theory of Operation
~
~
~
~
~
~
~
~
~
~
~
~
Vf
Vr
Vf1
Vr1
Iant
Uant
Vf1
CPU
ADC
inputs
INT1
AREF
Vph_
DD1_
DATA
CLK
WR1
L1...L9
Ld
C1...C16
Vph
DD1
WR2
SW75
FREQ
f
f/n
CHANEL CHANGE
ph+
ph-
T1
WR3
INT0
WR4
==
Ph
R+
R-
R
G+
G-
G
RESET
TUNE
OVER
SCL
RAM
SDA
OK
+24V
STU
+5V
R xD
TxD
UART
Figure 3-3. Control Board TS5.283 Functional Diagram
3-8
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