Garmin AT
Rev --
7-56
GX Service Manual
© 2004 Garmin AT
2. Press SEL to activate selection. The Mic 1 value will flash.
3. Turn the small knob to change the value.
4. Turn the large knob to the Mic 2 value. Turn the small knob to change the value.
5. Press ENTER to accept and save the settings.
Receiver Squelch
Preset the receiver squelch level for values from 25-100.
1. In the Test Mode, rotate the large knob to select Receiver Squelch.
2. Press SEL to activate selection. The value will flash.
3. Turn the small knob to select a value.
4. Press ENTER to accept and save the settings.
5. VHF Comm Checkout (GX60/65)
Receiver/Transmitter Operation
Tune the unit to a local frequency and verify the receiver output produces a clear and
understandable audio output. Verify the transmitter functions properly by contacting another
station and getting a report of reliable communications. Check the remote flip/flop.
Antenna Check
The antenna VSWR can be checked using an inline wattmeter in the antenna coax using
frequencies near both ends of the band. The VSWR should be < 2:1, and is not to exceed 3:1. A
VSWR of 2:1 will cause a drop in output power of approximately 12%, and 3:1 causes
approximately a 26% drop.
Sidetone Level Adjustment
The sidetone volume was preset at the factory to a typical audio level. The level can be adjusted
using one of the built-in system functions. To adjust the sidetone level:
1. Press SYS, rotate the large knob to the COM Info page, and press ENTER.
2. Rotate the large knob to the Sidetone Level page.
3. Press SEL, rotate the small knob to adjust the sidetone level, then press ENTER when
complete. The sidetone level is displayed in a range of 000 to 255, with 255 the highest level.
The sidetone level can be adjusted during transmit.
Comm Flight Test Check
A flight test is recommended as a final installation verification. The performance may be verified
by contacting a ground station at a range of at least 50nm while maintaining an appropriate
altitude and over all normal flight attitudes. Performance should be checked using low, high, and
mid band frequencies.
Summary of Contents for APOLLO GX SERIES
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