Codan 8525B Series Operating manual
HF SSB Transceiver
8525B/8528 series
Technical Service Manual
Volume 1
1989 Codan Pty Ltd.
ACN 007 590 605
Order code 15-02036
Issue 6, November 1995
Head Office
Codan Pty Ltd
ACN 007 590 605
81 Graves Street
Newton
South Australia 5074
International +61 8 8305 0311
Facsimile +61 8 8305 0411
Marketing Offices
Codan (U.K.) Ltd
Gostrey House
Union Road
Farnham, Surrey GU9 7PT
United Kingdom
International +44 1252 717 272
Facsimile +44 1252 717 337
Telex 858355
Codan Pty Ltd
Suite 11A, 2 Hardy Street
South Perth
Western Australia 6151
International +61 8 9368 5282
Facsimile +61 8 9368 5283
Publication No: 15-02036 Issue 6
Table of Contents
1 General Information
1.1 Introduction ........................................................................................................1-1
1.2 Specifications .....................................................................................................1-2
1.2.1 General ............................................................................................1-2
1.2.2 Receiver...........................................................................................1-4
1.2.3 Transmitter......................................................................................1-6
1.2.4 Rear Panel Connectors ....................................................................1-7
1.2.5 Front Panel Connector...................................................................1-10
1.3 Options and Accessories ..................................................................................1-11
1.3.1 Options..........................................................................................1-11
1.3.2 Accessories....................................................................................1-12
1.4 Abbreviations ...................................................................................................1-13
1.5 Circuit Reference Designations........................................................................1-20
1.6 Units.................................................................................................................1-21
1.7 Unit Multipliers................................................................................................1-21
2 Block Diagram
3 Brief Description
3.1 General ...............................................................................................................3-1
3.2 Receive...............................................................................................................3-1
3.3 Transmit .............................................................................................................3-2
3.4 Synthesizers........................................................................................................3-2
3.5 Display, Control and Switching .........................................................................3-3
3.6 External Power Amplifiers.................................................................................3-3
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Issue 6 Publication No: 15-02036
4 Technical Description
4.1 Control and Supply Voltages..............................................................................4-1
4.1.1 Supply Voltages ..............................................................................4-1
4.1.2 Power and Control Lines.................................................................4-2
4.1.3 Overvoltage and Reverse Voltage Protection..................................4-2
4.1.4 Transceiver Power On/Off ..............................................................4-2
4.1 5 High Power Transceiver Protection and Power On/Off..................4-3
4.2 Receiver..............................................................................................................4-4
4.2.1 Input Filters .....................................................................................4-4
4.2.2 Mixers, First IF Amplifiers and Filters ...........................................4-4
4.2.3 Noise Blanker..................................................................................4-5
4.2.4 IF Crystal Filter and Amplifier........................................................4-5
4.2.5 Demodulator....................................................................................4-5
4.2.6 Audio Mute .....................................................................................4-6
4.2.7 Volume Control and Audio Amplifier............................................4-6
4.3 Transmitter Exciter.............................................................................................4-7
4.3.1 Microphone Amplifier.....................................................................4-7
4.3.2 Modulator........................................................................................4-7
4.3.3 Crystal Filter....................................................................................4-8
4.3.4 Mixers, IF Filters and IF Amplifier.................................................4-8
4.4 Local Oscillators.................................................................................................4-9
4.4.1 Voltage Controlled Oscillators (VCO)............................................4-9
4.4.2 Phase/Frequency Detectors and Dividers........................................4-9
4.4.3 Lock Signals..................................................................................4-10
4.4.4 Loading of Frequency Data to Synthesizers..................................4-10
4.4.5 1650/1647kHz Local Oscillators...................................................4-11
4.4.6 Clarifier .........................................................................................4-11
8525B/8528 Technical Service Manual Table of Contents iii
Publication No: 15-02036 Issue 6
4.5 Microprocessor Controller PCB (04-02451 & 04-03031)................................4-12
4.5.1 Microcontroller Bus ......................................................................4-12
4.5.2 Internal I2C Bus.............................................................................4-13
4.5.3 External Bus..................................................................................4-14
4.5.4 Reset and Watchdog Circuit..........................................................4-14
4.5.5 RS-232 Port (ALE Option Only)...................................................4-14
4.6 Motherboard and Chassis (02-02453)..............................................................4-15
4.6.1 Power Supplies..............................................................................4-15
4.6.2 Antenna Control Facility...............................................................4-15
4.6.3 Extended or Remote Control—Option R......................................4-15
4.6.4 External Microphone Audio Clamp..............................................4-16
4.6.5 Additional Audio Facilities—Option RC......................................4-16
4.6.6 Headphone Output—Option PH ...................................................4-16
4.6.7 CW Facility—Option M................................................................4-16
4.6.8 External Selective Call or RTTY—Option PS..............................4-16
4.6.9 AGC Dump Circuit .......................................................................4-17
4.7 8525B Front Panels and Control Head.............................................................4-17
4.7.1 Display PCB..................................................................................4-17
4.7.2 Switch Matrix................................................................................4-18
4.7.3 Digiswitches..................................................................................4-18
4.7.4 Microphone Amplifier and Interface.............................................4-18
4.8 8528 Front Panel and Control Head.................................................................4-19
4.8.1 Display PCB, LCD........................................................................4-19
4.8.2 Indicator and Display Dimming....................................................4-20
4.8.3 Links..............................................................................................4-20
4.8.4 Switch Matrix................................................................................4-21
4.8.5 Microphone Amplifier and Interface.............................................4-21
4.8.6 8532 Display Head........................................................................4-21
iv Table of Contents 8525B/8528 Technical Service Manual
Issue 6 Publication No: 15-02036
4.9 PA and Filters (04-02452)................................................................................4-24
4.9.1 Introduction...................................................................................4-24
4.9.2 PTT Control...................................................................................4-24
4.9.3 Gain Control Stage........................................................................4-24
4.9.4 Pre-Driver Stages ..........................................................................4-24
4.9.5 Driver Stage...................................................................................4-25
4.9.6 Output Stage and Bias Regulator ..................................................4-25
4.9.7 Output Filters and Control.............................................................4-25
4.9.8 ALC Control..................................................................................4-26
4.9.9 Transmit Indicator.........................................................................4-27
4.10 PA Exciter Interface.........................................................................................4-27
4.10.1 Introduction...................................................................................4-27
4.10.2 Control Lines.................................................................................4-27
4.10.3 Power On/Off................................................................................4-27
4.10.4 PTT Circuit....................................................................................4-27
4.10.5 Transmit Amplifier........................................................................4-28
4.10.6 Receive Circuit..............................................................................4-28
4.10.7 Antenna Control............................................................................4-28
4.10.8 PA Unit..........................................................................................4-28
4.11 Selective Calling (04-02250)............................................................................4-29
4.11.1 Selective Calling ...........................................................................4-29
4.11.2 Selective Call Detection (04-02250).............................................4-30
4.12 Two-Tone Calling ............................................................................................4-31
4.12.1 Two-Tone Calling.........................................................................4-31
4.12.2 Two-Tone Detection......................................................................4-31
4.13 Option PS—External Signalling Interface .......................................................4-33
4.13.1 External Selective Calling.............................................................4-33
4.13.2 Selective Call Scanning.................................................................4-34
4.13.3 RTTY—ARQ mode......................................................................4-34
8525B/8528 Technical Service Manual Table of Contents v
Publication No: 15-02036 Issue 6
4.14 Options.............................................................................................................4-36
4.14.1 F—Fan Assembly..........................................................................4-36
4.14.2 LU—Switched LSB Operation......................................................4-36
4.14.3 L—Lower Sideband Operation .....................................................4-37
4.14.4 M—CW Facility............................................................................4-37
4.14.5 PH—Headphone Output ...............................................................4-37
4.14.6 R—Extended/Remote Control Interface.......................................4-37
4.14.7 AD—Antenna Driver....................................................................4-37
5 Operating Instructions
6 Maintenance
6.1 General ...............................................................................................................6-1
6.1.1 CMOS Devices................................................................................6-1
6.1.2 Circuit Boards .................................................................................6-1
6.1.3 Transmitter Precautions...................................................................6-3
6.1.4 Probe Precautions............................................................................6-3
6.1.5 Surface Mounted Components........................................................6-3
6.2 Fault Diagnosis...................................................................................................6-4
6.2.1 General ............................................................................................6-4
6.2.2 Voltage Measurement......................................................................6-5
6.2.3 Front Panel Controls........................................................................6-6
6.2.4 Logic Levels....................................................................................6-7
6.2.5 No Reception...................................................................................6-7
6.2.6 No Transmission .............................................................................6-8
6.2.7 Unlocked Synthesizer......................................................................6-8
6.2.8 Typical PA Voltages........................................................................6-8
vi Table of Contents 8525B/8528 Technical Service Manual
Issue 6 Publication No: 15-02036
6.3 Dismantling and Re-assembly............................................................................6-9
6.3.1 General ............................................................................................6-9
6.3.2 Top and Bottom Covers ..................................................................6-9
6.3.3 Circuit Board Removal....................................................................6-9
6.3.4 PA and Filter Assembly ................................................................6-10
6.3.5 Replacement of PA Transistors.....................................................6-11
6.3.6 Replacement of Escutcheon or Switch Substrate..........................6-12
7 Adjustments
7.1 Introduction ........................................................................................................7-1
7.2 Channel Addition (EPROM Replacement)........................................................7-1
7.2.1 Channel Addition, Programming P Channels (8528)......................7-2
7.3 Preset Adjustments.............................................................................................7-5
7.3.1 Test Equipment Required................................................................7-5
7.3.2 Voltage Regulators..........................................................................7-6
7.3.3 Crystal Oven....................................................................................7-6
7.3.4 VCO Adjustments (RF Mixer and Dual Synthesizer PCB)............7-6
7.3.5 45MHz IF Alignment—Receive .....................................................7-7
7.3.6 1650kHz IF Alignment....................................................................7-7
7.3.7 45MHz IF Alignment—Transmit....................................................7-7
7.3.8 Highpass Filters...............................................................................7-9
7.3.9 Noise Limiter.................................................................................7-10
7.3.10 Frequency Adjustment (USB).......................................................7-10
7.3.11 Frequency Adjustment (LSB)........................................................7-10
7.3.12 Mute Adjustments.........................................................................7-11
7.3.13 PA Adjustments.............................................................................7-11
7.3.14 Output Power.................................................................................7-11
7.3.15 Options SD, SDE and SDEM........................................................7-13
7.3.16 Option TD .....................................................................................7-13
8525B/8528 Technical Service Manual Table of Contents vii
Publication No: 15-02036 Issue 6
7.3.17 Selective Call Code Settings (8525B)...........................................7-14
7.3.18 Message Length Setting ................................................................7-15
7.3.19 Selective Call Code Settings (8528)..............................................7-15
7.4 Receiver Performance Checks..........................................................................7-16
7.4.1 Sensitivity and Signal + Noise to Noise Ratio..............................7-16
7.4.2 AGC Check...................................................................................7-16
7.4.3 Audio Output.................................................................................7-16
7.4.4 Selectivity (USB Operation)..........................................................7-16
7.4.5 Clarifier Operation ........................................................................7-16
7.4.6 Noise Limiter Operation................................................................7-16
7.5 Transmitter Performance Checks.....................................................................7-17
7.5.1 Frequency......................................................................................7-17
7.5.2 Clarifier .........................................................................................7-17
7.5.3 ALC...............................................................................................7-17
7.5.4 Power Output and Intermodulation Distortion..............................7-17
7.6 Emergency Call Frequencies............................................................................7-18
8 Parts List
8.1 General Information ...........................................................................................8-1
8.1.1 Ordering Information.......................................................................8-1
8.1.2 Component Substitution..................................................................8-2
8.2 Parts List.............................................................................................................8-3
9 Diagrams
viii Table of Contents 8525B/8528 Technical Service Manual
Issue 6 Publication No: 15-02036
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