iv
8.3 Dual Tone Multiple Frequency (DTMF) Data............................................. 2-18
9.0 Receive Audio Circuits.......................................................................................2-19
9.1 Squelch Detect .......................................................................................... 2-19
9.2 Audio Processing and Digital Volume Control ........................................... 2-20
9.3 Audio Amplification Speaker (+) Speaker (-) .............................................2-20
9.4 Handset Audio ........................................................................................... 2-21
9.5 Filtered Audio and Flat Audio ....................................................................2-21
10.0 Receive Signalling Circuits ................................................................................2-21
10.1 Sub-Audio Data (PL/DPL) and High Speed Data Decoder........................ 2-21
10.2 Alert Tone Circuits .....................................................................................2-22
Chapter 3 TROUBLESHOOTING CHARTS
1.0 Troubleshooting Flow Chart for Receiver RF (Sheet 1 of 2)................................ 3-2
1.1 Troubleshooting Flow Chart for Receiver (Sheet 2 of 2) ............................. 3-3
2.0 Troubleshooting Flow Chart for 45 W Transmitter (Sheet 1 of 3) ........................3-4
2.1 Troubleshooting Flow Chart for 45 W Transmitter (Sheet 2 of 3) ................ 3-5
2.2 Troubleshooting Flow Chart for 45 W Transmitter (Sheet 3 of 3) ................ 3-6
3.0 Troubleshooting Flow Chart for Synthesizer........................................................3-7
4.0 Troubleshooting Flow Chart for VCO...................................................................3-8
5.0 Troubleshooting Flow Chart for DC Supply (1 of 2).............................................3-9
5.1 Troubleshooting Flow Chart for DC Supply (2 of 2)...................................3-10
Chapter 4 VHF1 PCB / SCHEMATICS / PARTS LISTS
1.0 Allocation of Schematics and Circuit Boards .......................................................4-1
1.1 VHF1 and Controller Circuits .......................................................................4-1
2.0 VHF 25–45 W Band 1 PCB 8486487Z03 / Schematics....................................... 4-3
VHF 1 Interconnection between Main Board and Power Amplifier
Compartment ......................................................................................................4-3
VHF 1 (136–162 MHz) 25–45 W 8486487Z03, Top Side View ..........................4-4
VHF 1 (136–162 MHz) 25–45 W 8486487Z03, Bottom Side View ..................... 4-5
VHF 1 (136–162 MHz) 25–45 W Main Circuit (Sht 1 of 2) ..................................4-6
VHF 1 (136–162 MHz) 25–45 W Main Circuit (Sht 2 of 2) ..................................4-7
VHF 1 (136–162 MHz) 25–45 W Transmitter (Sht 1 of 2) ..................................4-8
VHF 1 (136–162 MHz) 25–45 W Transmitter (Sht 2 of 2) ..................................4-9
VHF 1 (136–162 MHz) 25–45 W Synthesiser and VCO (Sht 1 of 2) ................ 4-10
VHF 1 (136–162 MHz) 25–45 W Synthesiser and VCO (Sht 2 of 2) ................ 4-11
VHF 1 (136–162 MHz) 25–45 W Receiver Front and Back End (Sht 1 of 2) .... 4-12
VHF 1 (136–162 MHz) 25–45 W Receiver Front and Back End (Sht 2 of 2) .... 4-13
VHF 1 (136–162 MHz) 25–45 W DC and Audio Circuits (Sht 1 of 2) ............... 4-14
VHF 1 (136–162 MHz) 25–45 W DC and Audio Circuits (Sht 2 of 2) ............... 4-15
VHF 1 (136–162 MHz) 25–45 W Microprocessor and Controller Circuits
(Sht 1 of 2) ........................................................................................................4-16
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