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Installing the GPSMAP 172/172C
The GPSMAP 172/172C must be properly installed according to the following instructions to get
the best possible performance. If you have the GPSMAP 172/172C with the built-in internal antenna,
you may skip this section and proceed to the next page. For units purchased with the remote GA 29
antenna, follow the instructions below. To complete the installation, you’ll need the appropriate fasten-
ers and a 1” x 14-thread marine antenna mount available at most marine dealers. When in doubt,
seek professional assistance.
Mounting the GPS Antenna
The antenna should be mounted in a location that has a clear, unobstructed view of the sky in all
directions to ensure the best reception. Avoid mounting the antenna where it is shaded by the boat’s
superstructure, a radome antenna, or mast. Sailboat users should avoid mounting the antenna high
on the mast to prevent inaccurate speed readings caused by excessive heeling. Most marine VHF and
LORAN antennas should not seriously degrade the GPS antenna’s reception. Never paint the antenna or
clean it with harsh solvents.
The Garmin antenna screws directly onto any standard 1” x 14-thread antenna mount. If you
need to raise the antenna to avoid shading, try using a 1” x 14-thread extension mast available at most
marine dealers.
To install the GPS antenna:
1. Screw the antenna directly onto the 1” x 14-thread mount.
2. Route the cable to the mounting location of the display unit. Use the appropriate tie-wraps, fasten
-
ers and sealant to secure the cable along the route and through any bulkhead or deck.
3. Once the GPSMAP 172/172C unit has been installed, connect the cable to the antenna connec
-
tor on the back of the display unit. Make sure that you turn the antenna cable connector 1/4 turn
clockwise to lock the cable into place.
It is possible to route the coaxial cable either through, or
outside the antenna mount. It is possible to remove the
BNC connector on the coaxial cable and the coaxial cable
shortened to ease installation, however, doing so voids the
antenna warranty. If the BNC connector is removed it must
be replaced with a new solder-on or crimp BNC connector.
Suggested locations for mounting the GA 29 antenna.
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Appendix G
Antenna Installation