Garmin APOLLO GX SERIES Service Manual

Contents

Garmin AT Rev --© 2004 Garmin AT GX Service Manual 7-27Spurious Emission without ModulationThis is an optional test not required for returning a unit to service.1. Key the transmitter on a clear channel near 127.5 MHz.2. Observe the carrier output with a spectrum analyzer and record for reference.3. Measure power level at 2 nd harmonic (255 MHz).4. Measure the power level of the 3 rd harmonic (382 MHz).5. Measure the power level of all harmonics up to the 10 th harmonic.Note: If the dynamic range of the spectrum analyzer is not great enough, insert a high pass filter(188 MHz) between the transmitter and spectrum analyzer. Be sure to calibrate out the high passfilter’s insertion loss.Harmonic energy: ______ down at least 65 dBc3. Receiver TestsHeadset Output Level1. Inject a 1000 μV RF signal with 85% AM modulation into the Comm antenna port.2. Channel the Comm to the same frequency as the signal generator.3. Connect a 100 ohm resistor and AC power meter (or voltmeter) across the headphoneoutput.4. Turn up the volume control on the Comm radio to make sure the output power can be greaterthan 280 milliwatts (5.92 Vrms across 100 ohms).Headphone drive capable of 280 mW: _____ OKSpeaker Audio Level1. Inject a 1000 μV RF signal with 85% AM modulation into the Comm antenna port.2. Channel the Comm to the same frequency as the signal generator.3. Connect a 4 ohm resistor and AC power meter (or voltmeter) across the speaker output.4. Turn up the volume control on the Comm radio to make sure the output power can be greaterthan 12 watts (6.93 Vrms volts across 4 ohms).Speaker drive capable of 12 Watts: _____ OK