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 ......................................................................................1-2
Section 2 Theory of Operation
1.0 Introduction ..........................................................................................................2-1
2.0 Low Band Receiver..............................................................................................2-1
2.1 Receiver Front-End ........................................................................................2-1
2.2 Front-End Band-Pass Filters and Pre-Amplifier .............................................2-2
2.3 First Mixer and High Intermediate Frequency (IF)..........................................2-2
2.4 High Intermediate Frequency (IF) and Blanker Switches...............................2-2
2.5 Low Intermediate Frequency (IF) and Receiver Back End.............................2-3
2.6 “Extender” (Noise Blanker).............................................................................2-3
3.0 Transmitter Power Amplifier (PA) 60 W...............................................................2-4
3.1 Power Controlled Stage..................................................................................2-4
3.2 Driver Stage....................................................................................................2-5
3.3 Final Stage .....................................................................................................2-5
3.4 Antenna Switch...............................................................................................2-5
3.5 Harmonic Filter...............................................................................................2-5
3.6 Power Control.................................................................................................2-6
3.7 TX Safety Switch ............................................................................................2-6
4.0 Frequency Synthesis ...........................................................................................2-7
4.1 Fractional-N Synthesizer ................................................................................2-7
4.2 Voltage Controlled Oscillator (VCO) and Buffers ...........................................2-8
4.3 Synthesizer Operation....................................................................................2-9
Section 3 Troubleshooting Charts
1.0 Troubleshooting Flow Chart for Receiver (Sheet 1 of 2)......................................3-1
2.0 Troubleshooting Flow Chart for Transmitter ........................................................3-3
3.0 Troubleshooting Flow Chart for Synthesizer........................................................3-4
4.0 Troubleshooting Flow Chart for VCO...................................................................3-5