Motorola GM338

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Table of Contents
Section 1 Model Chart and Technical Specifications
1.0 GM338 Model Chart.............................................................................................1-1
2.0 Technical Specifications ......................................................................................1-1
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 1st Intermediate Frequency (IF) ............................................2-2
2.4 2nd Intermediate Frequency (IF) and Receiver Back End .............................2-3
3.0 Transmitter Power Amplifier (PA) 45 W...............................................................2-3
3.1 Power Controlled Stage..................................................................................2-4
3.2 Pre Driver Stage.............................................................................................2-4
3.3 Driver Stage....................................................................................................2-4
3.4 Final Stage .....................................................................................................2-4
3.5 Directional Coupler.........................................................................................2-4
3.6 Antenna Switch...............................................................................................2-5
3.7 Harmonic Filter...............................................................................................2-5
3.8 Power Control.................................................................................................2-5
4.0 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 45W Transmitter................................................3-3
3.0 Troubleshooting Flow Chart for Synthesizer........................................................3-5
4.0 Troubleshooting Flow Chart for VCO...................................................................3-6