Garmin GNC400, Alignment Procedure

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GNC 400 COMM TRANSCEIVER ALIGNMENT PROCEDURE
P/N 005-00051-55 REV. T
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TABLE OF CONTENTS
1. GENERAL...................................................................................................... 3
2. REFERENCE DOCUMENTS ......................................................................... 3
2.1 Test Equipment ............................................................................................................................. 3
2.2 Setup Procedure............................................................................................................................ 4
3. COMM TRANSCEIVER ASSEMBLY ALIGNMENT....................................... 5
3.1 Initial Control Settings ................................................................................................................. 5
3.1.1 Discrete Adjustment................................................................................................................ 5
3.1.2 Digital Pots ............................................................................................................................. 6
3.1.3 Covers ..................................................................................................................................... 6
3.2 Synthesizer Alignment.................................................................................................................. 6
3.2.1 VCO Alignment ...................................................................................................................... 6
3.2.2 TCXO Alignment.................................................................................................................... 7
3.3 Transmitter Power MOSFET Bias Setting................................................................................. 7
3.3.1 Bias Settings for –04 and Lower 10 Watt Comm Boards ....................................................... 7
3.3.2 Bias Settings for –05 and Higher 10 Watt, and 16 Watt Comm Boards ................................. 7
3.4 Receiver IF Alignment.................................................................................................................. 8
3.4.1 IF Alignment – 8.33 KHz Mode ............................................................................................. 8
3.4.2 IF Alignment - 25 KHz Mode................................................................................................. 8
3.5 Receiver / Transmitter Digital Pot Adjustments ........................................................................ 9
3.5.1 Comm Automated Alignment Instructions.............................................................................. 9
3.5.2 Receiver Preselector Alignment.............................................................................................. 9
3.5.3 Receiver Noise Squelch Calibration - 25 KHz Mode ............................................................. 9
3.5.4 Receiver Carrier Squelch Calibration - 25 KHz Mode ......................................................... 10
3.5.5 Receiver Carrier Squelch Calibration - 8.33 kHz Mode ....................................................... 11
3.5.6 Transmitter Output Power Calibration.................................................................................. 11
3.5.7 Transmitter Modulator Adjust .............................................................................................. 11
3.5.7.1 Modulator Adjustment for 10 Watt comm boards ............................................................ 11
3.5.7.2 Modulator Adjustment for 16 Watt comm boards ............................................................ 12
3.5.8 Transmitter Sidetone Adjust ................................................................................................. 12