Garmin GNC 420 GPS Receiver User Manual


 
Page 5-20 400 SERIES MAINTENANCE MANUAL
Rev. C P/N 190-00140-05
7. Adjust the RF level to 20 µV.
8. Verify the DMM reading is greater than the AGC reference voltage.
DMM reading ________VDC (NLT AGC Reference Voltage)
9. Adjust the signal generator frequency to 127.008 MHz.
10. Verify the DMM reading is greater than the reference AGC voltage.
127.008 MHz ______VDC (NLT AGC Reference Voltage)
126.992 MHz ______VDC (NLT AGC Reference Voltage)
11. Adjust signal level to 10 mV.
127.025 MHz ______VDC (NGT AGC Reference Voltage)
126.975 MHz ______VDC (NGT AGC Reference Voltage)
5.7.2.14 Selectivity (8.33 kHz Mode)
1. Put unit in the 8.33 kHz mode.
2. Tune to 127.000 MHz.
3. Turn the modulation OFF on the RF Signal Generator.
4. Turn the power/volume control knob fully counterclockwise, but not past the detent (OFF)
position.
5. Apply a 10 PV RF signal at 127.000 MHz.
6. Monitor the AGC voltage with the DMM (DC) at J2-2.
7. The DC voltage reading on the DMM is the AGC reference voltage, write it down as you will
need it for the rest of the test.
AGC Reference Voltage ______VDC
8. Adjust the RF level to 20 PV.
9. Verify the DMM reading is greater than the AGC reference voltage.
DMM Reading ______VDC (NLT AGC reference voltage)
10. Adjust the signal generator frequency to 127.002778 MHz.