Nav Antenna; Weight And Balance; Figure 2-12 - Rear Coaxc; Ear C Oax C Onnector A Ssembly - Garmin GNS 480 Installation Manaul

GNS 480 performance has been verified in typical installations and has not shown
problems of the built-in COM interfering with the GPS when installed according to the
recommended installation guidelines.
If a VHF COM transmitter causes problems with the GPS on the selected frequencies as listed in the post-
installation checkout, the problem may be due to the ELT. This can be verified by disconnecting the ELT
antenna coax at the ELT unit. If the ELT is found to cause the problem, then contact the ELT
manufacturer or replace the ELT.
2.9.3

NAV Antenna

The NAV antenna is a standard 50Ω horizontally polarized NAV/VOR/Localizer/Glideslope antenna that
receives VOR frequencies between 108 and 117.95 MHz, and localizer frequencies between 108 and 112
MHz, and glideslope information between 328.6 and 335.4 MHz. Follow the antenna manufacturer's
installation instructions for mounting antennas. The NAV antenna should be mounted as far apart as
practical from the ELT antenna. It is recommended that the installer use RG-142B or equivalent 50Ω coax
for the NAV antenna.
The GNS 480 incorporates an internal diplexor circuit. This means that the input VHF signal must not
strip the glideslope (330 MHz) signal from the NAV (108 MHz) signal. Do not install an external
diplexor. It is recommended that a single VOR/Localizer/Glideslope antenna be used for the installation.
Most VOR/LOC-only antennas will still provide an adequate glideslope signal for the GNS 480 to operate
normally.
If two nav receivers (e.g. one GNS 480 and one SL30) are installed in the aircraft, a splitter must be used.
Installations should use an appropriate splitter, such as the Mini-Circuits ZFSC-2-1B BNC, available as an
option under the Garmin AT part number 115-0007.

2.10 Weight and Balance

Weight and balance computation is required after the installation of the GNS 480. Follow the guidelines as
GNS 480 (CNX80) Installation Manual
NOTE
Figure 2-12 - Rear Coax Connector Assembly
560-0982-01 Rev L
Installation Procedures
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