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VHF (136-174 MHz) Frequency Synthesis
2-9
In order to modulate the PLL, the two spot modulation method is utilized. Via U3201 pin 10 (MODIN),
the audio signal is applied to both the A/D converter (low frequency path) as well as the balance
attenuator (high frequency path). The A/D converter changes the low frequency analog modulating
signal into a digital code that is applied to the loop divider, thereby causing the carrier to deviate. The
balance attenuator is used to adjust the VCO’s deviation sensitivity to high frequency modulating
signals. The output of the balance attenuator is present at the MODOUT port (U3201-41) and
connected to the VCO modulation diode D3362 via R3364.
Summary of Contents for GM338
Page 1: ...GM328 GM338 GM398 Mobile Radios Detailed Service Manual 6804112J18 E December 2003 ...
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Page 7: ...GM328 GM338 GM398 Mobile Radios Service Maintainability Issue December 2003 ...
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Page 20: ...1 4 Radio Model Information THIS PAGE INTENTIONALLY LEFT BLANK ...
Page 32: ...2 12 Notes For All Schematics and Circuit Boards THIS PAGE INTENTIONALLY LEFT BLANK ...
Page 35: ...GM328 GM338 GM398 Mobile Radios Controlhead Service Information Issue December 2003 ...
Page 42: ...1 4 GM398 Model GCN6115_ THIS PAGE INTENTIONALLY LEFT BLANK ...
Page 56: ...2 14 Controlhead Model for GM398 THIS PAGE INTENTIONALLY LEFT BLANK ...
Page 70: ...4 2 Allocation of Schematics and Circuit Boards THIS PAGE INTENTIONALLY LEFT BLANK ...
Page 88: ...4 20 Controlhead GM398 PCB 8486178B03 Schematics THIS PAGE INTENTIONALLY LEFT BLANK ...
Page 89: ...GM328 GM338 GM398 Mobile Radios Controller Service Information Issue December 2003 ...
Page 114: ...2 2 Controller Troubleshooting Chart THIS PAGE INTENTIONALLY LEFT BLANK ...
Page 140: ...3 26 Controller T7 T9 Schematic Diagrams THIS PAGE INTENTIONALLY LEFT BLANK ...
Page 141: ...GM328 GM338 GM398 Mobile Radios VHF 136 174MHz Service Information Issue December 2003 ...
Page 148: ...1 4 Technical Specifications THIS PAGE INTENTIONALLY LEFT BLANK ...
Page 158: ...2 10 VHF 136 174 MHz Frequency Synthesis THIS PAGE INTENTIONALLY LEFT BLANK ...
Page 166: ...3 8 Troubleshooting Flow Chart for VCO THIS PAGE INTENTIONALLY LEFT BLANK ...
Page 168: ...4 2 Allocation of Schematics and Circuit Boards THIS PAGE INTENTIONALLY LEFT BLANK ...
Page 186: ...4 20 VHF 1 25W PCBs Schematics Parts Lists THIS PAGE INTENTIONALLY LEFT BLANK ...
Page 187: ...GM328 GM338 GM398 Mobile Radios UHF 403 470MHz Service Information Issue December 2003 ...
Page 204: ...2 10 UHF 403 470 MHz Frequency Synthesis THIS PAGE INTENTIONALLY LEFT BLANK ...
Page 212: ...3 8 Troubleshooting Flow Chart for VCO THIS PAGE INTENTIONALLY LEFT BLANK ...
Page 214: ...4 2 Allocation of Schematics and Circuit Boards THIS PAGE INTENTIONALLY LEFT BLANK ...
Page 235: ...GM328 GM338 GM398 Mobile Radios UHF Band 2 450 527MHz Service Information Issue December 2003 ...
Page 252: ...2 10 UHF 450 527 MHz Frequency Synthesis THIS PAGE INTENTIONALLY LEFT BLANK ...
Page 260: ...3 8 Troubleshooting Flow Chart for VCO THIS PAGE INTENTIONALLY LEFT BLANK ...
Page 262: ...4 2 Allocation of Schematics and Circuit Boards THIS PAGE INTENTIONALLY LEFT BLANK ...
Page 274: ...4 14 UHF Band 2 1 25W PCBs Schematics Parts List THIS PAGE INTENTIONALLY LEFT BLANK ...
Page 275: ...GM338 GM398 Mobile Radios Low Band Service Information Issue December 2003 ...
Page 280: ...iv THIS PAGE INTENTIONALLY LEFT BLANK ...
Page 284: ...1 4 Technical Specifications THIS PAGE INTENTIONALLY LEFT BLANK ...
Page 300: ...3 6 Troubleshooting Flow Chart for VCO THIS PAGE INTENTIONALLY LEFT BLANK ...
Page 378: ...4 78 Low Band PCBs Schematics Parts Lists THIS PAGE INTENTIONALLY LEFT BLANK ...
Page 379: ...GM338 Mobile Radios VHF 45W Bipolar 136 174MHz Service Information Issue December 2003 ...
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Page 411: ...GM338 Mobile Radios UHF1 40W Bipolar 403 470MHz Service Information Issue December 2003 ...
Page 426: ...2 10 Frequency Synthesis THIS PAGE INTENTIONALLY LEFT BLANK ...
Page 432: ...3 6 Troubleshooting Flow Chart for VCO THIS PAGE INTENTIONALLY LEFT BLANK ...
Page 434: ...4 2 Allocation of Schematics and Circuit Boards THIS PAGE INTENTIONALLY LEFT BLANK ...
Page 446: ...4 14 UHF 25 40W PCB Schematics Parts List THIS PAGE INTENTIONALLY LEFT BLANK ...
Page 447: ...GM338 Mobile Radios UHF2 40W Bipolar 450 520MHz Service Information Issue December 2003 ...
Page 462: ...2 10 Frequency Synthesis THIS PAGE INTENTIONALLY LEFT BLANK ...
Page 468: ...3 6 Troubleshooting Flow Chart for VCO THIS PAGE INTENTIONALLY LEFT BLANK ...
Page 470: ...4 2 Allocation of Schematics and Circuit Boards THIS PAGE INTENTIONALLY LEFT BLANK ...
Page 482: ...4 14 UHF Band 2 25 40W PCB Schematics Parts List THIS PAGE INTENTIONALLY LEFT BLANK ...
Page 483: ...GM338 Mobile Radio UHF B1 HIGH POWER LDMOS 403 470MHz Service Information Issue December 2003 ...
Page 498: ...2 10 UHF 403 470 MHz Frequency Synthesis THIS PAGE INTENTIONALLY LEFT BLANK ...
Page 506: ...4 2 Allocation of Schematics and Circuit Boards THIS PAGE INTENTIONALLY LEFT BLANK ...
Page 518: ...4 14 UHF 25 40W PCB Schematics Parts List THIS PAGE INTENTIONALLY LEFT BLANK ...
Page 534: ...2 10 UHF 450 520 MHz Frequency Synthesis THIS PAGE INTENTIONALLY LEFT BLANK ...
Page 540: ...3 6 Troubleshooting Flow Chart for VCO THIS PAGE INTENTIONALLY LEFT BLANK ...
Page 542: ...4 2 Allocation of Schematics and Circuit Boards THIS PAGE INTENTIONALLY LEFT BLANK ...
Page 554: ...4 14 UHF Band 2 25 40W PCB Schematics Parts List THIS PAGE INTENTIONALLY LEFT BLANK ...