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Codan 8525B Series Technical & Service Manual
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1-10 General Information
8525B/8528 Technical Serv
ice Manual
Issue 6
Publication No: 15-02036
1.2.5
Fr
ont Panel Connector
Microphon
e Connector
Pin Num
ber
Func
tion
1
PTT ground
2
PTT active low
3
Microphone input
4
Microphone
ground
5
Speaker
connection*
6
Audio output
7
Audio output
*Linked to pin 7 for front panel speaker operation.
19
21
Table of Contents
Default Chapter
3
Table of Contents
3
Issue 6 Publication No:
10
1 General Information
11
Introduction
11
Specifications
12
General
12
Receiver
14
Transmitter
16
Rear Panel Connectors
17
Front Panel Connector
20
Options and Accessories
21
Options
21
Accessories
22
Abbreviations
23
Circuit Reference Designations
30
Units
31
Unit Multipliers
31
2 Block Diagram
33
3 Brief Description
33
General
33
Receive
33
Transmit
34
Synthesizers
34
Display, Control and Switching
35
External Power Amplifiers
35
4 Technical Description
37
Control and Supply Voltages
37
Supply Voltages
37
Power and Control Lines
38
Overvoltage and Reverse Voltage Protection
38
Transceiver Power On/Off
38
High Power Transceiver Protection and Power On/Off
39
Receiver
40
Input Filters
40
Mixers, First if Amplifiers and Filters
40
Noise Blanker
41
IF Crystal Filter and Amplifier
41
Demodulator
41
Audio Mute
42
Volume Control and Audio Amplifier
42
Transmitter Exciter
43
Microphone Amplifier
43
Modulator
43
Crystal Filter
44
Mixers, if Filters and if Amplifier
44
Local Oscillators
45
Voltage Controlled Oscillators (VCO)
45
Phase/Frequency Detectors and Dividers
45
Lock Signals
46
Loading of Frequency Data to Synthesizers
46
1650/1647Khz Local Oscillators
47
Clarifier
47
Microprocessor Controller PCB (04-02451 & 04-03031)
48
Microcontroller Bus
48
Internal I C Bus
50
External Bus
51
Reset and Watchdog Circuit
51
Port (ALE Option Only)
51
Motherboard and Chassis (02-02453)
52
Power Supplies
52
Antenna Control Facility
52
Extended or Remote Control-Option R
52
External Microphone Audio Clamp
53
Additional Audio Facilities-Option RC
53
Headphone Output-Option PH
53
CW Facility-Option M
53
External Selective Call or RTTY-Option PS
53
AGC Dump Circuit
54
8525B Front Panels and Control Head
54
Display PCB
54
Switch Matrix
55
Digiswitches
55
Microphone Amplifier and Interface
55
8528 Front Panel and Control Head
56
Display PCB, LCD
56
Indicator and Display Dimming
57
Links
57
Switch Matrix
58
Microphone Amplifier and Interface
58
8532 Display Head
58
PA and Filters (04-02452)
61
Introduction
61
PTT Control
61
Gain Control Stage
61
Pre-Driver Stages
61
Driver Stage
62
Output Stage and Bias Regulator
62
Output Filters and Control
62
ALC Control
63
Transmit Indicator
64
PA Exciter Interface
64
Introduction
64
Control Lines
64
Power On/Off
64
PTT Circuit
64
Transmit Amplifier
65
Receive Circuit
65
Antenna Control
65
PA Unit
65
Selective Calling (04-02250)
66
Selective Calling
66
Selective Call Detection (04-02250)
67
Two-Tone Calling
68
Two-Tone Detection
68
Option PS-External Signalling Interface
70
External Selective Calling
70
Selective Call Scanning
71
RTTY-ARQ Mode
72
Options
73
F-Fan Assembly
73
LU-Switched LSB Operation
73
L-Lower Sideband Operation
74
M-CW Facility
74
PH-Headphone Output
74
R-Extended/Remote Control Interface
74
AD-Antenna Driver
74
5 Operating Instructions
77
6 Maintenance
79
General
79
CMOS Devices
79
Circuit Boards
79
Transmitter Precautions
81
Probe Precautions
81
Surface Mounted Components
81
Fault Diagnosis
82
General
82
Voltage Measurement
83
Front Panel Controls
84
Logic Levels
85
No Reception
85
No Transmission
86
Unlocked Synthesizer
86
Typical PA Voltages
86
Dismantling and Re-Assembly
88
General
88
Top and Bottom Covers
88
Circuit Board Removal
88
PA and Filter Assembly
89
Replacement of PA Transistors
90
Replacement of Escutcheon or Switch Substrate
91
7 Adjustments
93
Introduction
93
Channel Addition (EPROM Replacement)
93
Channel Addition, Programming P Channels (8528)
94
Preset Adjustments
97
Test Equipment Required
97
Voltage Regulators
98
Crystal Oven
98
VCO Adjustments (RF Mixer and Dual Synthesizer PCB)
98
45Mhz if Alignment-Receive
99
1650Khz if Alignment
99
45Mhz if Alignment-Transmit
99
Highpass Filters
101
Noise Limiter
102
Frequency Adjustment (USB)
102
Frequency Adjustment (LSB)
102
Mute Adjustments
103
PA Adjustments
103
Output Power
104
Options SD, SDE and SDEM
105
Option TD
105
Selective Call Code Settings (8525B)
106
Message Length Setting
107
Receiver Performance Checks
108
Sensitivity and Signal + Noise to Noise Ratio
108
AGC Check
108
Audio Output
108
Selectivity (USB Operation)
108
Clarifier Operation
108
Noise Limiter Operation
108
Transmitter Performance Checks
109
Frequency
109
Clarifier
109
Alc
109
Power Output and Intermodulation Distortion
109
Emergency Call Frequencies
110
8 Parts List
111
General Information
111
Ordering Information
111
Component Substitution
112
Parts List
113
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Handbook
189 pages
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Codan 8525B Series Specifications
General
Brand
Codan
Model
8525B Series
Category
Transceiver
Language
English
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