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IFD5XX Installation Manual
600-00299-000
Page 43 of 198
Revision: 02
3.3.6 GPS Interference
After installing the IFD5XX System, the GPS antenna must be tested to insure no interference
is present. The GPS Antenna System is subject to interference from VHF COM transceiver,
Emergency Locator Transmitter (ELT) antenna, or Direction Finder (DF) receiver which can
radiate harmonics that can potentially interfere with the GPS antenna.
If a VHF Communication transceiver is found to be the problem, installing a 1.57542 GHz
notch filter may help to reduce the problem.
3.3.7 Ground Plane
The GPS Antenna should be mounted on a minimum of 8 x 8 inch metal surface or ground
plane.
3.3.8 Dual IFD5XX Installations
If the aircraft has dual IFD5XX, the aircraft is permitted to have a non-WAAS system and a
WAAS system installed, however, if the two antennas are not of the same type (i.e. dual non-
WAAS or dual WAAS installation), then FMS-related data (flight plans, waypoints, routes,
etc) will not be shared between IFDs.
3.3.9 Anti-Ice Protection
If the aircraft is approved for flight into known icing, verify the GPS antenna is installed in
location that is not susceptible to ice buildup or complies with FAA AC 20-138( ) paragraph
13-2.
3.4 VHF Communication Antenna
The VHF communication antenna should be installed using this manual, FAA AC 43.13-( ),
AC 20-67B and the antenna manufacturer’s guidance.
The antennas should be installed to allow maximum separation between antennas. If
possible, one antenna should be installed on the top of the aircraft, and the other on the
bottom of the aircraft.
3.4.1 Antenna Environmental Qualifications
Verify the antenna is appropriately qualified to be installed on the aircraft. Reference the
antenna manufacturer’s RTCA DO-160(x) qualification form.
3.4.2 VHF Communication Cable
The antenna cable should be RG-142B, RG-400, or an equivalent 50 coaxial cable.
3.4.3 VHF Coaxial Cable Connector
The connectors on the VHF communication coaxial cable should be assembled per the
connector manufacturer’s assembly instructions.
3.4.4 Voltage Standing Wave Ratio
The VSWR should not exceed 2:1 over the VHF communication radio frequency range. A
VSWR over 2:1 may result in loss in transmitting power up to 50%.
Summary of Contents for IFD540
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