Barrett 900 Series User manual

Technical manual
Barrett 900 series HF transceivers and receivers
BARRETT 930, 950, 980 local control HF transceivers
BARRETT 930, 950 remote control ( trunk mount) HF transceivers
BARRETT 950M HF transceiver module
BARRETT 950MR HF receiver
BARRETT 940 HF portable transceiver
BARRETT COMMUNICATIONS©
© Barrett Communications
BCM90000/4
:
Barrett Communications Pty Ltd Barrett Europe Limited
10 Port Kembla Drive, Bibra Lake WA 6163 19 Lenten Street
P O Box 1214, Bibra Lake WA 6965 Alton, Hampshire
AUSTRALIA GU34 1HG
Toll Free Tel: [phone] UNITED KINGDOM
Tel: [phone] Tel: [phone]
Fax: [phone] Fax: [phone], P3
Head office: European office
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BARRETT 900 SERIES TRANSCEIVERS

1.0 Specifications ... ............ ............ ............ ............ ............ ............ ............ ............ ............ ............5
1.1 General Specifications... ............ ............ ............ ............ ............ ............ ............ ............5
1.2 Receiver Specifications . ............ ............ ............ ............ ............ ............ ............ ............7
1.3 Transmitter Specifications .......... ............ ............ ............ ............ ............ ............ ............8
2.0 Introduction....... ............ ............ ............ ............ ............ ............ ............ ............ ............ ............9
3.0 Overview .......... ............ ............ ............ ............ ............ ............ ............ ............ ............ ............11
3.1 Front Panel ....... ............ ............ ............ ............ ............ ............ ............ ............ ............11
3.2 Microprocessor PCB...... ............ ............ ............ ............ ............ ............ ............ ............11
3.3 RF/Audio PCB .. ............ ............ ............ ............ ............ ............ ............ ............ ............11
3.4 PA PCB ............ ............ ............ ............ ............ ............ ............ ............ ............ ............12
3.5 Remote Control Head .... ............ ............ ............ ............ ............ ............ ............ ............12
3.6 940 front panel .. ............ ............ ............ ............ ............ ............ ............ ............ ............12
3.7 940 connector transition PCB...... ............ ............ ............ ............ ............ ............ ............12
4.0 Technical description ..... ............ ............ ............ ............ ............ ............ ............ ............ ............13
4.1 Microprocessor PCB...... ............ ............ ............ ............ ............ ............ ............ ............13
4.1.2 Power supplies . ............ ............ ............ ............ ............ ............ ............ ............13
4.1.3 Reference oscillator (Standard) .. ............ ............ ............ ............ ............ ............13
4.1.4 Reference oscillator (High stability option) ............ ............ ............ ............ ............13
4.1.5 Microprocessor. ............ ............ ............ ............ ............ ............ ............ ............13
4.1.6 DDFS and VCO. ............ ............ ............ ............ ............ ............ ............ ............15
4.1.7 Selcall (if enabled).......... ............ ............ ............ ............ ............ ............ ............17
4.1.8 Audio mute........ ............ ............ ............ ............ ............ ............ ............ ............17
4.1.9 PA ALC control voltage PWR ADJ ............ ............ ............ ............ ............ ............18
4.2 RF / Audio PCB . ............ ............ ............ ............ ............ ............ ............ ............ ............19
4.2.1 RF section......... ............ ............ ............ ............ ............ ............ ............ ............19
4.2.1.1 .30 MHz Low pass filter, first mixer and 45 MHz IF amplifier.. ............ ............19
4.2.1.2 .Second mixer and bandpass crystal filter.. ............ ............ ............ ............21
4.2.1.3 .Noise blanker.... ............ ............ ............ ............ ............ ............ ............21
4.2.1.4 .Noise gate......... ............ ............ ............ ............ ............ ............ ............21
4.2.1.5 .Second IF, AGC and demodulator ............ ............ ............ ............ ............21
4.2.1.6 .Transmit and receive switching ... ............ ............ ............ ............ ............21
4.2.2 Audio section .... ............ ............ ............ ............ ............ ............ ............ ............21
4.2.2.1 .Audio path......... ............ ............ ............ ............ ............ ............ ............22
4.3 PA PCB ............ ............ ............ ............ ............ ............ ............ ............ ............ ............24
4.3.1 Gain control amp............ ............ ............ ............ ............ ............ ............ ............24
4.3.2 Low pass filters . ............ ............ ............ ............ ............ ............ ............ ............24
4.3.3 ALC control ....... ............ ............ ............ ............ ............ ............ ............ ............24
4.3.4 Over-voltage and reverse voltage protection......... ............ ............ ............ ............24
4.3.5 Auxiliary antenna socket ............ ............ ............ ............ ............ ............ ............24
4.3.6 Receiver RF amplifier..... ............ ............ ............ ............ ............ ............ ............24
4.3.7 Power supply regulators. ............ ............ ............ ............ ............ ............ ............24
4.4 Front panel........ ............ ............ ............ ............ ............ ............ ............ ............ ............26
4.4.1 LCD and status LED's .... ............ ............ ............ ............ ............ ............ ............26
4.4.2 Keypad ............ ............ ............ ............ ............ ............ ............ ............ ............26
4.4.3 Backlighting ...... ............ ............ ............ ............ ............ ............ ............ ............26
4.4.4 Microphone....... ............ ............ ............ ............ ............ ............ ............ ............26
4.4.5 Volume control and On/Off switch ............ ............ ............ ............ ............ ............26
5.0 Maintenance..... ............ ............ ............ ............ ............ ............ ............ ............ ............ ............30
5.1 Introduction....... ............ ............ ............ ............ ............ ............ ............ ............ ............30
5.2 Printed Circuit Board (PCB) maintenance ............ ............ ............ ............ ............ ............30
5.3 Component replacement ............ ............ ............ ............ ............ ............ ............ ............30
5.4 CMOS devices.. ............ ............ ............ ............ ............ ............ ............ ............ ............31
5.5 Transmitter power amplifier maintenance precautions ....... ............ ............ ............ ............31
5.6 PCB access ...... ............ ............ ............ ............ ............ ............ ............ ............ ............31
5.6.1 930 - 950 - 980 transceivers......... ............ ............ ............ ............ ............ ............31
5.6.2 940 transceivers ............ ............ ............ ............ ............ ............ ............ ............31
5.6.3 930 - 950 remote control head ..... ............ ............ ............ ............ ............ ............31
4.5 Remote control head...... ............ ............ ............ ............ ............ ............ ............ ............28
BARRETT 900 SERIES TRANSCEIVERS
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5.7 Fault diagnosis.. ............ ............ ............ ............ ............ ............ ............ ............ ............32
5.7.1 General ............ ............ ............ ............ ............ ............ ............ ............ ............32
5.7.2 Transceiver will not power up ...... ............ ............ ............ ............ ............ ............33
5.7.3 Transceiver will not receive but displays OK .......... ............ ............ ............ ............35
5.7.3.1 No receiver noise at all ... ............ ............ ............ ............ ............ ............35
5.7.3.2 Receive noise present, but does not receive.......... ............ ............ ............35
5.7.3.4 Transceiver turns on but displays "Barrett 900 Transceiver" only. .... ............35
5.7.4 Transceiver turns on, internal voltages are normal, but no LCD display......... ............36
5.7.5 Main microprocessor faults ......... ............ ............ ............ ............ ............ ............36
5.7.6 VCO faults ........ ............ ............ ............ ............ ............ ............ ............ ............37
5.7.7 Transmitter faulty ........... ............ ............ ............ ............ ............ ............ ............37
5.7.8 Replacement of PA output and driver transistors ... ............ ............ ............ ............38
5.8 Adjustments...... ............ ............ ............ ............ ............ ............ ............ ............ ............40
5.8.1 Front panel........ ............ ............ ............ ............ ............ ............ ............ ............40
5.8.2 Microprocessor PCB...... ............ ............ ............ ............ ............ ............ ............40
5.8.2.1 Reference oscillator setup (Standard oscillator) .... ............ ............ ............40
5.8.2.2 Reference oscillator setup (High stability oscillator)............ ............ ............40
5.8.2.3 VCO frequency adjustment......... ............ ............ ............ ............ ............40
5.8.2.4 Carrier Insertion oscillator peaking........... ............ ............ ............ ............40
5.8.2.5 VCO Low pass filter........ ............ ............ ............ ............ ............ ............40
5.8.2.6 DAC Low pass filter ........ ............ ............ ............ ............ ............ ............41
5.8.3 RF/ Audio PCB.. ............ ............ ............ ............ ............ ............ ............ ............41
5.8.3.1 Input low pass filter......... ............ ............ ............ ............ ............ ............41
5.8.3.2 45MHz IF Filter.. ............ ............ ............ ............ ............ ............ ............41
5.8.3.3 IF Inductors....... ............ ............ ............ ............ ............ ............ ............42
5.8.3.4 Noise blanker potentiometer ....... ............ ............ ............ ............ ............42
5.8.3.5 Carrier rejection potentiometer.... ............ ............ ............ ............ ............42
5.8.3.6 Transmit drive level set potentiometer ...... ............ ............ ............ ............42
5.8.3.7 455Khz IF ......... ............ ............ ............ ............ ............ ............ ............42
5.8.4 PA PCB ............ ............ ............ ............ ............ ............ ............ ............ ............42
5.8.4.1 Driver bias setup ............ ............ ............ ............ ............ ............ ............42
5.8.4.2 PA bias setup .... ............ ............ ............ ............ ............ ............ ............42
5.8.4.3 Power level adjustment .. ............ ............ ............ ............ ............ ............43
5.3.4.4 Programmable links ....... ............ ............ ............ ............ ............ ............43
6.0 Software programming and options ......... ............ ............ ............ ............ ............ ............ ............44
6.1 Barrett 930 transceivers . ............ ............ ............ ............ ............ ............ ............ ............44
6.2 Barrett 940 transceivers . ............ ............ ............ ............ ............ ............ ............ ............44
6.3 Barrett 950 transceivers . ............ ............ ............ ............ ............ ............ ............ ............44
6.4 Barrett 980 transceivers . ............ ............ ............ ............ ............ ............ ............ ............44
7.0 Internal jumper settings ............ ............ ............ ............ ............ ............ ............ ............ ............45
7.1 Standard jumpers locations ........ ............ ............ ............ ............ ............ ............ ............45
7.2 Configuring antenna connectors . ............ ............ ............ ............ ............ ............ ............45
8.0 Internal options ............ ............ ............ ............ ............ ............ ............ ............ ............ ............46
8.1 Internal scrambler option ............ ............ ............ ............ ............ ............ ............ ............46
8.2 Internal GPS receiver option ....... ............ ............ ............ ............ ............ ............ ............48
8.3 Internal ALE option P/N BCA95001 and BCA95002 ........... ............ ............ ............ ............48
9.0 Features and configurations unique to transceiver models . ............ ............ ............ ............ ............49
9.1 Barrett 950 transceivers fitted with high stability option - P/N BC95001 and BC95003 ............49
9.2 Barrett 950M transceiver module - P/N BC95004 .. ............ ............ ............ ............ ............49
9.3 Barrett 950MR receivers ............ ............ ............ ............ ............ ............ ............ ............49
9.4 Barrett 940 man-pack..... ............ ............ ............ ............ ............ ............ ............ ............50
9.4.1 940 ancillary components ........... ............ ............ ............ ............ ............ ............50
9.4.1.1 110 to 240 VAC input charger supply Barrett P/N BCA94012 ........... ............50
9.4.1.2 Charge regulator suit 13Ah NiMH battery 12V DC input P/N BCA94021 ...50
9.4.1.3 940 multiple-use distribution unit Barrett P/N BCA94010.... ............ ............51
9.4.1.4 940 automatic antenna tuner....... ............ ............ ............ ............ ............51
9.5 Barrett 980 GMDSS transceiver .. ............ ............ ............ ............ ............ ............ ............52
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BARRETT 900 SERIES TRANSCEIVERS

10.0 Accessory interface unit - P/N BCA90016 ............ ............ ............ ............ ............ ............ ............53
11.0 Auxiliary connector ........ ............ ............ ............ ............ ............ ............ ............ ............ ............54
11.1 Barrett 980 and Barrett 950 transceivers .. ............ ............ ............ ............ ............ ............54
11.2 Barrett 930 transceivers . ............ ............ ............ ............ ............ ............ ............ ............55
11.3 Barrett 940 manpack transceivers............ ............ ............ ............ ............ ............ ............56
12.0 Circuit diagrams, overlays and parts lists.. ............ ............ ............ ............ ............ ............ ............57
Active component outlines .......... ............ ............ ............ ............ ............ ............ ............ ............57
RF/Audio PCB overlay ... ............ ............ ............ ............ ............ ............ ............ ............ ............58
RF/Audio schematic....... ............ ............ ............ ............ ............ ............ ............ ............ ............59
RF/Audio parts List - showing optional narrow filter components. .... ............ ............ ............ ............61
Microprocessor PCB overlay....... ............ ............ ............ ............ ............ ............ ............ ............72
Microprocessor schematic .......... ............ ............ ............ ............ ............ ............ ............ ............73
Microprocessor parts list ............ ............ ............ ............ ............ ............ ............ ............ ............75
PA PCB overlay. ............ ............ ............ ............ ............ ............ ............ ............ ............ ............87
PA schematic .... ............ ............ ............ ............ ............ ............ ............ ............ ............ ............89
PA parts list ....... ............ ............ ............ ............ ............ ............ ............ ............ ............ ............91
Front panel PCB overlay ............ ............ ............ ............ ............ ............ ............ ............ ............99
Front panel schematic.... ............ ............ ............ ............ ............ ............ ............ ............ ............100
Front panel parts list ....... ............ ............ ............ ............ ............ ............ ............ ............ ............101
Remote control head PCB overlay ........... ............ ............ ............ ............ ............ ............ ............103
Remote control head schematic .. ............ ............ ............ ............ ............ ............ ............ ............104
Remote control head parts list ..... ............ ............ ............ ............ ............ ............ ............ ............105
Scrambler PCB overlay Barrett P/N BCA94031 ... ............ ............ ............ ............ ............ ............108
Scrambler schematic ..... ............ ............ ............ ............ ............ ............ ............ ............ ............109
Scrambler parts list ........ ............ ............ ............ ............ ............ ............ ............ ............ ............110
GPS/ALE motherboard overlay... ............ ............ ............ ............ ............ ............ ............ ............111
GPS/ALE motherboard schematic ........... ............ ............ ............ ............ ............ ............ ............112
GPS/ALE motherboard parts list . ............ ............ ............ ............ ............ ............ ............ ............113
950MR Low Pass Filter/Power PCB overlay.......... ............ ............ ............ ............ ............ ............114
950MR Low Pass Filter/Power PCB schematic ..... ............ ............ ............ ............ ............ ............115
950MR Low Pass Filter/Power PCB parts list ........ ............ ............ ............ ............ ............ ............117
980PSU DC/DC switch mode power supply PCB overlay ... ............ ............ ............ ............ ...........121
980PSU DC/DC switch mode power supply schematic ...... ............ ............ ............ ............ ............122
980PSU DC/DC switch mode power supply parts list.......... ............ ............ ............ ............ ............123
900 series final assembly parts lists.......... ............ ............ ............ ............ ............ ............ ............125
930, 940, 950, 980 hand microphone schematic.... ............Barrett P/N BCA90003 ... ............ ............133
930, 950, 980 cloning cable schematic ..... ............ ............Barrett P/N BCA90024 ... ............ ............134
930, 950, 980 programming cable schematic ........ ............Barrett P/N BCA90023 ... ............ ............135
940 chassis explosion diagram ... ............ ............ ............ ............ ............ ............ ............ ............136
940 connector transition PCB overlay ...... ............ ............ ............ ............ ............ ............ ............139
940 connector transition schematic.......... ............ ............ ............ ............ ............ ............ ............140
940 connector transition parts list ............ ............ ............ ............ ............ ............ ............ ............141
940 automatic antenna tuner PCB overlay ............ ............Barrett P/N BCA94009 ... ............ ............142
940 automatic antenna tuner ... ............ ............Barrett P/N BCA94009 ... ............ ............143
940 auto tuner PCB parts list.......... .......... ............ ............ ............ ............ ............ ............ ............146
940 multiple-use distribution unit schematic .......... ............Barrett P/N BCA94010 ... ............ ............151
940 multiple-use distribution unit parts list ............ ............Barrett P/N BCA94010 ... ............ ............152
940 charge reg. 13Ah / 12V DC input PCB overlay. ............Barrett P/N BCA94021 ... ............ ............153
940 charge reg. 13Ah / 12V DC input PCB schematic .........Barrett P/N BCA94021 ... ............ ............154
940 battery charger PCB parts list ............ ............ ............Barrett P/N BCA94021 ... ............ ............157
940 handset lightweight tactical schematic............ ............Barrett P/N BCA94004 ... ............ ............161
940 transceiver mic schematic ............ ............ ............Barrett P/N BCA94013 ... ............ ............162
940 programming cable schematic .......... ............ ............Barrett P/N BCA94013 ... ............ ............163
940 final assembly parts list......... ............ ............ ............ ............ ............ ............ ............ ............137
schematic
940 automatic antenna tuner final assembly parts list (Drab Olive, Periwinkle) .......... ............ ............147
940 tuner front panel PCB overlay ............ ............ ............ ............ ............ ............ ............ ............148
940 tuner front panel PCB schematic ....... ............ ............ ............ ............ ............ ............ ............149
940 ATU front panel PCB parts list............ ............ ............ ............ ............ ............ ............ ............150
940 transceiver cloning cable schematic .. ............ ............Barrett P/N BCA94014 ... ............ ............160
BARRETT 900 SERIES TRANSCEIVERS
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1.0 Specifications
BARRETT 980
BARRETT 950 BARRETT
930 BARRETT 950M
BARRETT 950MR
BARRETT 940
930, 940, 950
980
930, 950
930, 950
980
940
980
1.1 General Specifications
Equipment GMDSS transceiver.
transceiver local and remote control models
transceiver local and remote control models
transceiver module
receiver module (disregard references to transmit
specifications and descriptions)
man-pack transceiver (power output limited to 10 - 35 W
(adjustable))
Transmit frequency range 1.6 MHz to 30 MHz (continuous)
Receive frequency range 500 kHz to 30 MHz (continuous)
Channel capacity 980 local and remote control models, 950 local and remote control
models, 950R and 950MR1 receivers and - Up to
450 programmable channels (simplex or semi-duplex)
930 local and remote control models - Up to 20 programmable channels
(simplex or semi-duplex)
Frequency resolution 10 Hz program mode
1 Hz tuneable receiver (940, 950 and 980 transceivers)
Frequency stability Standard ±50 Hz (0 to +55 C)
Optional ±10 Hz (-15 C to +55 C)(Standard 980)
Intermediate frequencies 45 MHz and 455 kHz (double conversion)
Operating modes J3E (USB, LSB)
H3E (AM)
J2A (CW)
J2B (AFSK) standard filter (980, 950 local and remote control models
only)
J2B (AFSK) narrow filter option (980, 950 local and remote control models
only)
Operating temperature -30 C to +55 C
Humidity 95% relative, non condensing
Display system Supertwist backlit LCD matrix, 16 character x 2 line
Controls 20 key keypad (illuminated), analogue power/volume
Supply voltage - 13.8 VDC + 20% / - 10% (negative ground)
Polarity protected. Over voltage protected
- 24 VDC +20% / -10% galvanically isolated from transceiver (using
matching, switch mode power supply)
Current consumption local control models 840 mA receive
receive. remote control models 860 mA receive
(24V) 450 mA receive
595 mA receive
Antenna Impedance 50 unbalanced
Compass Safe Distance GMDSS transceiver 2 metres
940 man-pack model
°°
°°
°°
W
BARRETT 900 SERIES TRANSCEIVERS
PAGE 5

Weight 3.6 Kg.
3.2Kg.
portable transceiver 3.9 Kg.
13 Ah NiMH battery pack 2.7 Kg
automatic antenna tuner 1.8 Kg.
Dimensions 250 mm x 75 mm x 300 mm
transceiver - no battery 275 mm x 97 mm x 210 mm
transceiver and battery 275 mm x 97 mm x 310 mm
transceiver, battery and top case 275 mm x 97mm x 405mm
automatic antenna tuner 275 mm x 53 mm x 210 mm
Selcall System Based on CCIR 493-4
Scan Types Selcall, Voice(syllabic), AGC derived signal level.
Scan Channels Two tables, programmable by channel.
Scan Rate Selcall Scan - Fixed at 500 ms.
Non Selcall scan - Adjustable from 100 ms to 5 secs
930, 950 and 980
950MR1
940
940
Optional 940
930 - 950 - 980
940
940
940
Optional 940
.
BARRETT 900 SERIES TRANSCEIVERS
PAGE 6

1.2 Receiver Specifications
Sensitivity 0.256uV (-119dBm) for 10dB SINAD - J3E Mode (With RF pre-amp on)
Selectivity J3E -1kHz and + 4kHz better than 60dB
Selectivity F1B (optional) -500Hz and + 500Hz better than 45dB
Desensitisation -1kHz and + 4kHz better than 60dB
-10kHz and +10kHz better than 71dB
-20kHz and +20kHz better than 80dB
-50kHz and +50kHz better than 87dB
The level of an unwanted signal above the level of a wanted signal that will
reduce the SINAD of the wanted signal producing 10dB SINAD to 7dB
SINAD
Image rejection Better than 76dB
Spurious response ratio Better than 70dB
Cross modulation -20kHz and +20kHz better than 82dB
The level of an unwanted signal that is 30% AM modulated and at
20kHz above the level of a wanted signal that is producing 10dB SINAD
that will cause this wanted signal SINAD to reduce by 3dB
Blocking -20kHz and +20kHz better than 80dB
The level of an unwanted signal above the level of a wanted signal that will
reduce the SINAD of the wanted signal producing 10dB SINAD to 7dB
SINAD
Intermodulation 85dB - the level of an unwanted signal in relation to a wanted signal.
Inband IMD Greater than 34dB
Clarifier range Receive only 1Hz steps up to ±1kHz (dependant on configuration).
AGC efficiency Less than 6.0 dB variation with an input signal of 6uV(-91.4dBm) to
3V(+22.5dBm).
Audio Output 4W into 4 Ohms, 2W into 8 Ohms at less than 5% distortion
Audio output impedance 2 to 80 Ohms
Audio response Less than 6dB variation from 350Hz to 2750Hz
Audio distortion Less than 5% at rated power J3E mode
Input protection Better than 30V RMS from a 50 ohm source
BARRETT 900 SERIES TRANSCEIVERS
PAGE 7

930 - 950
980
940
930, 950,980
940
930, 950, 980
940
1.3 Transmitter Specifications
RF Output Power 100 W PEP two tone ± 1 dB
125 W PEP voice ± 1 dB
or
10 W PEP two tone ± 1 dB
12 W PEP voice ± 1 dB
100 W PEP two tone ±1.5 dB
(portable) 25 W two tone 10 - 35 W PEP (factory set to user
requirement)
Duty Cycle 100% two-tone input signal with fan option
(portable) 25% voice duty cycle
Protection Safe under all load conditions, thermal protection against excessive power
transistor temperatures.
Sideband suppression Better than -65dB below PEP
Harmonic suppression Better than -60dB below PEP
Carrier suppression Better than -60dB below PEP
Spurious emission Better than -60dB below PEP
Intermodulation products Better than -31dB below PEP (25dB below two tone peak)
Audio frequency response Less than 6 dB variation 350 Hz to 2750 Hz
Current consumption Voice average less than 9Amps typical
Two tone less than 15Amps typical
Voice average less than 5Amps typical.
Two tone less than 9Amps typical.
BARRETT 900 SERIES TRANSCEIVERS
PAGE 8

BARRETT 900 SERIES TRANSCEIVERS
2.0 Introduction
This technical manual covers the Barrett 950 local and remote control transceiver, the Barrett 980 GMDSS
transceiver, the Barrett 940 man-pack transceiver, the Barrett 930 local and remote control transceiver, the
Barrett 950M transceiver module and the 950MR receivers. They have largely identical hardware and only
vary by key function and operational software and in the case of the 940 the mounting hardware and
enclosure.
PAGE 9

BARRETT 900 SERIES TRANSCEIVERS
PAGE 10
BARRETT 900
DRAWING NUMBER DATE ECN REFERENCE
BARRETT PART NO
DIMENSIONING
SCALE
NTS
DRAWN
DRAWING TITLE
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3.0 Overview
All 900 series transceivers and receivers are made up of several common building blocks. Apart from the
940 man-pack transceiver they are all constructed with a common chassis. This manual deals with each
module and has a separate section describing sections of transceivers and receivers that are unique
to that transceiver or receiver.
The 980/950/930/ local control transceivers are comprised of the following four modules:-
The 950/930 remote control transceivers are comprised of the following four modules:-
The 940 man-pack comprises the following six modules:-
The backlit keypad allows entry of channel number, transmit frequency, receive frequency, mode, Selcall,
power, scan, ATU option and customer specific information. A 2 line x 16 character backlit LCD display
annunciates the channel frequency and indicates which functions have been selected on this channel.
Numerous other status displays are optionally available. On the left hand side of the display 5 status LED's
indicate the current mode of the transceiver. A red LED is illuminated in transmit, a green LED in receive and
three yellow LED's indicate which of the three modes, USB, LSB or AM has been selected (J3E, H3E, F1B
on the 980 transceiver). A rotary volume control and on/off switch and a Mylar cone speaker are also
included on the front panel. The microphone which incorporates press to talk and channel up/down buttons,
plugs into an 8 pin socket on the front panel. Note:- The standard microphone has a jumper in it (refer to the
microphone diagrams) that enables the front panel speaker, the handset does not have this jumper thus
disabling the speaker.
The Microprocessor PCB is the central control of the transceiver. This PCB also contains the Direct Digital
Frequency Synthesis (DDFS) system which generates all local oscillator injection frequencies, the Selcall
demodulator and the audio syllabic mute sensing circuit.
The RF/Audio PCB contains the receiver and transmitter exciter, the audio processor section and general
interface to the outside of the transceiver. The receiver employs a double conversion superhet design with a
high dynamic range. All receiver signals are processed through either a single sideband filter which has a
passband of 2.4KHz or in the case of AFSK (J2B) signals, through a narrow sideband filter with a passband
of 500Hz. A product detector is used to demodulate all single sideband signals, whilst an envelope detector
is used to demodulate AM signals. An effective noise blanker, employing a separate pulse receiver, is
provided which may be switched on or off as required.
There is a great deal of commonality between receive and transmit paths in both the R.F. and audio circuits.
In transmit, audio from the microphone, the auxiliary input or the remote head is passed to an automatic level
control circuit which amplifies and maintains a constant modulating signal with considerable variations in
input signal level. This maintains an adequate modulation level in all circumstances.
On receive, the signal is amplified and fed to a mute circuit. Both receive and transmit audio share a
common path up to the volume control. The RS-232 computer interface is located on the RF/Audio PCB.
*Front Panel *Microprocessor PCB
*PA PCB *RF/Audio PCB
*Microprocessor PCB *PA PCB
*RF/Audio PCB Remote control head and interface cable
*Microprocessor PCB *PA PCB
*RF/Audio PCB *Front panel
*Connector transition PCB
*
3.1 Front Panel
3.2 Microprocessor PCB
3.3 RF/Audio PCB
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3.4 PA PCB
3.5 Remote Control Head
3.6 940 front panel
3.7 940 connector transition PCB
The PA PCB raises the power level to 25 W, 100 or 125 W PEP depending on the setup of the power amplifier
and the model. Seven low pass filters provide harmonic rejection over the full frequency range, reduce
receiver LO radiation and enhance image rejection of the receiver. Also resident on the PA PCB is power
protection circuitry guarding against over-voltage, reverse voltage and low voltage supplies.
ALC protection and regulation of the transmitter power output will protect the transceiver from reactive loads
plus open and short circuit antenna connections.
The remote head can be operated up to 20 metres from any 900 series transceiver (three remote head
interface cables joined together).
The control cable is connected to the remote head via a 9 pin "D" connector. The loudspeaker output being
by a 3.5 mm jack socket.
The remote head contains its own microprocessor to drive the display, but otherwise contains no controlling
intelligence. The remote head firmware is the same for 930, 950 and 980 transceivers - the only difference,
in the heads, being the front panel membrane and key functions.
The 940 front panel is a Barrett 900 series remote head fitted into an "O" ringed aluminium front panel. The
front half of the remote head plastic front panel is retained the rear half is removed. A special loom is fitted to
the remote head PCB to connect to the RF/Audio PCB. Also fitted to the front panel is a connector transition
PCB described below. In addition to the normal commercial microphone connector on the remote control
head panel there are two military connectors. The 5 pin panel socket provides a handset connection while
the other 8 pin panel plug provides interface signals to the 940 auto tuner, serial communications for
programming and cloning, CW key and power connections.
The connector transition PCB provides a microphone amplifier for the handset and transition from the IDC
connector to the military connectors.
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4.0 Technical description
The Microprocessor PCB incorporates the microprocessor unit which controls the transceiver system, the
synthesiser, which provides three stable local oscillator sources, the selcall encoder/decoder which
generates and demodulates selcall signals, and the audio syllabic mute and transmitter power control.
The transceiver has several internal voltage regulators to obtain +5 volt and +10 volt supplies used
throughout the transceiver. Where lowest power consumption is required, as in the 940 man-pack, some of
these have a switch mode regulator to replace the normally fitted linear regulators.
On the microprocessor PCB, U19 and U20 can be replaced by a single switch-mode regulator U36. Other
minor components that need to be added are L3, L6 C118, C119, C117, and C121.
The reference oscillator at 45.455 MHz is the master clock which determines the frequency and timing of all
other synchronous events in the transceiver. It consists of active devices Q13 and Q14 configured as a
Butler oscillator. L16 is set to cancel the crystal stray capacitance and L15 resonates with C132, C133 and
C137, C146 to provide fine frequency trimming. The oscillator is trimmed to 1ppm and an oven maintains a
constant crystal temperature. The output of the reference oscillator is fed direct to the second mixer on the
RF/Audio PCB via TP35 and is buffered prior to routing to the digital section by Q10 and Q11. These are
configured in cascode to minimise reverse coupling. Further buffering is obtained from inverter U31:A prior
to feeding the cascade flip flops U32:A and U32:B. These devices provide a 1:1 duty cycle clock for the
DDFS chip U7 at 22.72 MHz and the microprocessor U1 at 11.36 MHz. A further divider U13 yields 2.84
MHz clock for the Carrier Insertion Oscillator generation by the DDFS. Link LK2 must be IN and LK1 must be
OUT for the standard oscillator.
The reference oscillator at 45.455 MHz is the master clock which determines the frequency and timing of all
other synchronous events in the transceiver. It consists of either a modular TXCO or DCXO oscillating at
45.455 MHz. The oscillator frequency is trimmed using the adjustment on the top of the can. The output of
the TCXO is buffered by Q20, then fed direct to the second mixer on the RF/Audio PCB via TP35 and is
buffered prior to routing to the digital section by Q10 and Q11. These are configured in cascode to minimise
reverse coupling. Further buffering is obtained from inverter U31:A prior to feeding the cascade flip flops
U32:A and U32:B. These devices provide a 1:1 duty cycle clock for the DDFS chip U7 at 22.72 MHz and the
microprocessor U1 at 11.36 MHz. A further divider U13 yields 2.84 MHz clock for the Carrier Insertion
Oscillator generation in the DDFS. Link LK2 must be OUT and LK1 must be IN for the high stability oscillator
option.
The microprocessor U1 is the device which executes the control program for the transceiver. It executes
instructions stored in EPROM U4 and stores and reads non-volatile data from EEPROM U5. These are
connected via a sixteen line bus which has low order address and data multiplexed on the same eight lines.
The low address is de-multiplexed using octal latch U2. A security PAL U40 is also fitted on the data bus to
permit configuration security.
Two parallel output ports U15 (I/O Port 1) and U16 (I/O Port 0) handle static and slow logic signals from
microprocessor. These include PA filter select lines, Audio / IF control signals such as PTT, AM on and NB
on, Mic Disable, Speaker clamp and Mute and ATU control signals Tune Clock and Scan Data.
U14 (I/O port 3) is used to input parallel data from U35, a PWM decoder used to input key PCB data from the
front panel and remote head.
Decoding for all these peripheral devices is provided by 3 to 8 decoder U6 along with U3 and U11. Shift
register U17 ensures that the timing for the EEPROM operation is correct.
4.1 Microprocessor PCB
4.1.2 Power supplies
4.1.3 Reference oscillator (Standard)
4.1.4 Reference oscillator (High stability option)
4.1.5 Microprocessor
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MICROCONTROLLER
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The microprocessor has four sets of ports of its own used as follows:-
AN0 to AN7
CO1, CO0, CI, TO, INT2, SCK, RXD, TXD, PTTIN, CW KEY, ALESEN, GPSEN
PB0 to PB7
PA0 to PA7
Interrupts
4.1.6 DDFS and VCO
. These analogue input ports monitor transmit VSWR using voltages SWR+ and SWR-, receive
signal strength using voltage AGC, synthesiser lock state using voltage VCO Lock and battery voltage
utilising a voltage derived from a voltage divider consisting of R2 and R35. AN5 and AN6 are used to
measure voltages used to set up the selcall VCO tuning during the startup sequence. AN7 is used for
internal chassis temperature measurement, provided by sensor TS1, which is used for PA ALC trimming at
high temperatures.
CO1 and CO0 are counter/timer ports used to generate selcall transmit and alarm tones. CI and TO combine
to decode the received selcall pre -amble and data stream. INT2 is the main interrupt processing PTTIN and
CW KEY, SCK is unused. RXD and TXD are the external RS-232 serial ports. RXD and TXD are routed by
U44 and combinations of signals ALESEN and GPSEN to input and output data to and from an internally
fitted ALE controller option, as well as inputting data from either an external or internal GPS receiver. RESET
ALE is used to reset the ALE controller option when fitted.
is bi-directional and handles various slow speed input and output requirements such as Scan
Stop and Mute state.
handles further low speed signals including generation of annunciation beeps via signal
ALARM DATA.
are processed by the Interrupt Controller consisting of U18, U25 and U26. Lines PTTIN and CW
KEY are latched by signal ICP from the microprocessor. A magnitude comparator U25 compares the lines
with their previous state and requests an interrupt via INT2 if there is a state change.
The synthesiser employs a Direct Digital Frequency Synthesiser integrated circuit U7 which takes in
frequency data over the data bus with registers accessed by the 5 bit address field. The synthesiser is a dual
unit, half of which is used to generate 1/10 of the VCO frequency. The other half is the Carrier Insertion
Oscillator, the frequency of which is dependant on th type of I.F. filter used, and the mode of operation
chosen but is in the region of 455 kHz. The outputs of U7 are digitized sine waves which are decoded by
Digital to analog converters U8, U9, and U12. U8 and U9 are used to decode the VCO reference, and U12
decodes the carrier insertion output. T1 is a resonant transformer which yields a clean sine wave for the
carrier insertion signal.
In order to achieve a spurious free, low phase noise local oscillator, a high level(+13dBm) push pull VCO
operating at 10 times the DAC reference frequency is coupled to the DAC reference signal via a tracking
PLL.
Diodes D9, D10, D11, D12, D15, D16, D18, limit the voltage excursions on the FET gates maintaining
constant amplitude and low noise. An attenuator formed by resistors R187 to R189 and amplifier Q16 are
used to isolate the VCO from the low pass filter and first mixer circuits.
The VCO feeds the first mixer via a buffer amplifier comprising Q16 and T4 and a 76 MHz LPF consisting of
L10, L11, this provides some gain to present the mixer with a final LO1 level of 17 dBm and high reverse
isolation. It also feeds a cascode pre-scaler buffer consisting of Q8 and Q15 which has high reverse
isolation preventing unwanted sidebands on the VCO. U21 provides a further buffer for the divide by 10 pre-
scaler. This pre-scaler is a Johnson counter employing U23, U24 and U28. It is reset at power up by U29
which uses the same reset feed as the microprocessor. This ensures true counting.
The reference signal from the DACs at 1/10 VCO frequency is fed through an anti-alliasing filter L1, L2 and
through a common emitter buffer Q1 to the phase comparator.
A digital phase comparator using U21:B and U22 generates positive going differential error pulses at TP23,
TP24 according to the phase relationship of the DACs waveform and VCO/10. Charge balancing is
performed by the Charge Pump Q2, Q3, Q4 Q5 which integrates the error signal in a lead-lag loop filter C82,
C83, R58. This control or error signal can swing over the entire 0 to 10V range according to selected
frequency. It is fed to varactors D2, D6, D7 and D8 controlling the VCO frequency. The VCO frequency
range is 45 to 75 MHz being 45 MHz above the indicated frequency on the LCD display.
An out of lock red LED is driven by the phase comparator to provide fault indication. This signal also
generates a displayed error message and is used by the microprocessor to inhibit transmission if the VCO is
unlocked.
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DDFS
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4.1.7 Selcall (if enabled)
Australian Standard Selcall format(Codan compatible)
CCIR 493-4 International Standard format:-
Note:-
4.1.8 Audio mute
The selective system utilises Frequency Shift Keying (FSK) as the modulation technique. The design of the
encoder/decoder allows individual channels to be set for operation on either the Australian Standard Selcall
format(Codan comaptible, based on CCIR 493-4) or the true CCIR493-4 format and its associated tones.
Tones used are as follows:-
:-
High tone:- 1870 Hz Low tone:- 1700 Hz Centre tone:- 1785 Hz
High tone:- 1785 Hz Low tone:- 1615 Hz Centre tone:- 1700 Hz
Selcall (and other on air status tones) are generated by the microprocessor U1 and output on pins 26 (SEL
TX DATA1) and 27 (SEL TX DATA2). Transistors Q21 and Q22 combine the signals as necessary and this
signal is output to the RF/Audio PCB to be fed into the transmitted audio path.
Received Selcall signals are filtered by dual bandpass filter U41 A and B. The bandpass filters have
sufficient bandwidth to accommodate both tone sets as above. The audio from the filter output is fed into
the input of the FSK decoder chip XR2211, U27. The VCO within U27 is automatically set to the centre
frequency of the required selcall format. Calibration is performed each time the transceiver is powered up.
This is achieved by routing a single tone (Sel TX data 2) via U43 to the input bandpass filter and
subsequently to the FSK decoder U27. The tone is set to one of the centre frequencies referred to above.
Whilst injecting the tone the calibrating voltage PWR ADJ (see note below), generated by the DAC U38 and
buffered by U10, is varied until the voltage 2211 REF(TP40) and voltage FSK SET V, measured by the
microprocessor on analogue to digital inputs AN6 (U1 Pin 43) and AN5 (U1 Pin 42), are equal. At this point
the FSK centre frequency is set to that of the injected tone.
The signal PWR ADJ referred to above is the calibrating voltage for the selcall phase lock in receive
but changes to the PA ALC power adjustment control in transmit.
When FSK signals are detected the lock detect (U27 pin 6) on the FSK decoder goes high. This causes the
output of the comparator (U27 pin 7) to also go high, reverse biasing D31 and thus causing data to be output
by U42:B. The presence of data (SEL RX DATA) on the microprocessor (U1 pins 24and 25) causes an
interrupt and the subsequent processing of the digital selcall data by the microprocessor.
The Rx audio from the Audio / IF PCB is fed into U34:A which operates as a squaring amplifier. The squared
audio then feeds a charge pump consisting of D40, Q24 and surrounding components. this produces a DC
voltage which is proportional to the frequency of the audio (i.e. voltage rises as frequency increases).
IC33:B acts as a low pass filter with a cut-off frequency of approximately 10 Hz. The output from IC33:B is a
DC voltage which varies at the syllabic rate of the speech received. The absolute output level is also
proportional to the frequency content of the incoming signal as described above.
IC34:C and IC34:D make up a window comparator. The window width is adjusted by the mute sensitivity pot
VR2. The divider network R119 and R120 together with C190, averages the output of IC33:B to provide the
reference voltage for the window comparator. If the output from IC33:B rises or falls below this reference by
the amount set by VR2, then the open collector outputs of IC34:C and IC34:D will discharge C191 and apply
a low to the input of comparator IC34:B pin 6.
The second input of comparator, IC34:B, pin 7 is set to approx. 4 volts by resistor divider R123 and R124.
When input pin 6 falls below 4 volts, the comparator output, pin 1 goes high, this signal, MUTE STATE, is the
indication to the microprocessor that speech has been detected and, if the audio mute is selected, the mute
should be opened. The signal used to control the actual audio mute gate from the microprocessor is RX
MUTE which comes from U1 Pin 6. MUTE STATE is input to the microprocessor U1 on pin14.
When receiving no signal, the mute is held closed by noise coming from both the antenna and that
generated internally by the receiver. This noise has considerable high frequency content, which causes
sufficient output from charge pump mentioned above to hold the mute closed.
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Mute attack timing is controlled by C191 and R121. Release timing is set by C191 and R122 and
microprocessor introduced delays.
The signal PWR ADJ from the DAC U38 via buffer U10B is the calibrating voltage for the selcall phase lock in
receive but changes to the PA ALC power adjustment control in transmit. This voltage is varied by the
microprocessor to produce low and high RF power levels from the PA and is also used to trim the PA RF
power output at high temperature. (AN7 on the microprocessor has a temperature sensor on it for this
purpose)
4.1.9 PA ALC control voltage PWR ADJ
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4.2 RF / Audio PCB
The RF section of the RF / Audio PCB provides the complete exciter and receiver for the transceiver. It
includes:-
First mixer Roofing filter at 45 MHz
45 MHz IF amplifier with AGC 45 MHz Noise blanker receiver
Second mixer Noise blanker gate
SSB filter and narrow filter for AFSK Envelope detector for AM
Product detector for SSB,FSK and CW signals AGC detector
The RF section has a common RF input and output port and separate audio input for Tx and output for Rx. A
double superheterodyne system is used, with a first IF of 45MHz and second IF at 455 kHz. Three oscillator
injection frequencies are taken from the synthesiser, LO1 at (Carrier frequency + 45 MHz), LO2 at 45.455
MHz and LO3 or the Carrier Insertion Oscillator at 453.3kHz on USB and 456.6kHz on LSB. There is a
separate 45 MHz receiver to generate gating pulses for the noise blanker.
The audio section of the RF/Audio PCB handles the routing of audio signals in the transceiver and
implements audio processing and frequency tailoring. It also handles the extensive I/O with the outside
world such as Auxiliary 600 input and output (950, 980 only), computer Interface (950,980 only), ATU
Interface and external alarm. The audio power amplifiers for both the local and remote head speaker
outputs are also fitted on the RF/Audio PCB.
The 30 MHz low pass filter, L16, L20 and associated capacitors, minimises the image response of the
receiver. It also serves to control LO1 breakthrough on both Rx and Tx. The first mixer U29 and post mixer
amplifier Q1 is switched as a block between receive and transmit by relay RL1. The local oscillator level for
this mixer is +13dBm. The amplifier achieves the best possible broadband termination for the mixer IF port,
important to maintain low intermodulation distortion. The post mixer amplifier then feeds into the noise
blanker receiver via an isolation amplifier Q28, and also into the main receiver IF section via a dual section
45 MHz roofing filter giving medium selectivity of approximately +/- 3 kHz @ -3dB and +/-25 kHz @ 60dB.
The roofing filter feeds or is fed by the dual gate FET 45 MHz IF amplifier consisting of Q4 and Q5. The input
of this IF amplifier is matched to 50 by L1 and C21. The output is matched to 50 by the L network L9, C37.
AGC is applied to the 45 MHz IF amplifier via the second gates on Q4 and Q5. RL2 and RL3 control the Tx/Rx
turn around of this IF amplifier.
In transmit the 45MHz IF amplifier is reversed in its direction by relay RL2 and RL3, the output from the
second mixer is amplified by this 45MHz amplifier which in the transmit direction is gain controlled by a
voltage switched in place of the AGC signal. This voltage is adjusted by VR2 which sets the drive of the
exciter. The output of the 45MHz IF amplifier is then passed through the 45MHz roofing filter consisting of F2
and F2A and into the first mixer U29 and its associated post mixer pad and amplifier. The whole mixer, pad
and amplifier is reversed in the direction used in receive by relay RL1. The output of the mixer is fed into low
pass filter consisting of L16, L20 and associated capacitors.
4.2.1 RF section
4.2.1.1 30 MHz Low pass filter, first mixer and 45 MHz IF amplifier.
Receive
Transmit
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RF SECTION
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