Garmin Apollo GX50 GPS Installation Manual

Also see for APOLLO GX60: User guide Quick reference guide

Installation28 Apollo GX50/60/65 Installation Manual3. Check the signal reception using the GPS sensor displays in the System mode. Press theSYS button, rotate the LARGE knob to the “GPS SENSOR:” page, and press ENT. Thenrotate the SMALL knob to display the GPS info. Typical signal levels are 50 or better.4. Turn on other avionics one at a time and check the GPS signal reception to make sure itis not affected.5. Check for VHF comm transmitter interference. This must be completed on all IFRinstallations.a) Verify that 5 to 8 satellites are in DATA and the NAV flag is out of view.b) Tune the comm to 121.150 MHz and transmit for 20 seconds.c) Verify that the position is not lost.d) Repeat for additional frequencies as follows.121.125 MHz 131.225 MHz121.175 MHz 131.250 MHz121.200 MHz 131.275 MHz121.225 MHz 131.300 MHz121.250 MHz 131.325 MHz131.200 MHz 131.350 MHze) Repeat for each comm transmitter.f) If the GX50/60/65 is susceptible to VHF comm transmitter interference, then betterisolation, or distance, may be required between the GPS and VHF antennas. Withsome comm transmitters, a notch filter may be required in series with the VHFcomm antenna coax at the rear of the comm unit.Note: Older VHF comm transmitters may emit higher levels of harmonic interferencecausing greater problems and may be more difficult to deal with.VHF COMM CHECKOUT (GX60/65)Receiver / Transmitter OperationTune the unit to a local frequency and verify the receiver output produces a clear andunderstandable audio output. Verify the transmitter functions properly by contacting anotherstation and getting a report of reliable communications. Check the remote flip/flop.Antenna CheckThe antenna VSWR can be checked using an inline wattmeter in the antenna coax usingfrequencies 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 causesapproximately a 26% drop.Sidetone Level AdjustmentThe sidetone volume was preset at the factory to a typical audio level. The level can beadjusted 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 ENT.2. Rotate the LARGE knob to the “SIDETONE LEVEL” page.3. Press SEL, rotate the SMALL knob to adjust the sidetone level, then press ENT whencomplete. The sidetone level is displayed in a range of 000 to 255, with 255 the highestlevel. The sidetone level can be adjusted during transmit.