Motorola GM328

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Table of Contents
Section 1 Model Chart and Technical Specifications
1.0 GM328/GM338/GM398 Model Chart...................................................................1-1
2.0 Technical Specifications ......................................................................................1-2
Section 2 Theory of Operation
1.0 Introduction ..........................................................................................................2-1
2.0 VHF (136-174 MHz) Receiver..............................................................................2-1
2.1 Receiver Front-End ........................................................................................2-1
2.2 Front-End Band-Pass Filters & Pre-Amplifier.................................................2-2
2.3 First Mixer and High Intermediate Frequency (IF)..........................................2-2
2.4 Low Intermediate Frequency (IF) and Receiver Back End.............................2-3
3.0 VHF (136-174 MHz) Transmitter Power Amplifier (PA) 25 W..............................2-3
3.1 First Power Controlled Stage..........................................................................2-4
3.2 Power Controlled Driver Stage.......................................................................2-4
3.3 Final Stage .....................................................................................................2-4
3.4 Directional Coupler.........................................................................................2-5
3.5 Antenna Switch...............................................................................................2-5
3.6 Harmonic Filter...............................................................................................2-5
3.7 Power Control.................................................................................................2-5
4.0 VHF (136-174 MHz) Frequency Synthesis ..........................................................2-6
4.1 Reference Oscillator.......................................................................................2-6
4.2 Fractional-N Synthesizer ................................................................................2-6
4.3 Voltage Controlled Oscillator (VCO)...............................................................2-7
4.4 Synthesizer Operation....................................................................................2-8
Section 3 Troubleshooting Charts
1.0 Troubleshooting Flow Chart for Receiver ............................................................3-1
2.0 Troubleshooting Flow Chart for 25W Transmitter................................................3-3
3.0 Troubleshooting Flow Chart for Synthesizer........................................................3-6
4.0 Troubleshooting Flow Chart for VCO...................................................................3-7