---------------------------------------------------------- Avionics-List Digest Archive --- Total Messages Posted Sun 02/23/03: 2 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 09:21 AM - GPS Interference from Comms (Lynn Manhart) 2. 09:33 AM - Re: GPS Interference from Comms (HornetBall@aol.com) ________________________________ Message 1 _____________________________________ Time: 09:21:43 AM PST US From: "Lynn Manhart" Subject: Avionics-List: GPS Interference from Comms --> Avionics-List message posted by: "Lynn Manhart" Does anyone monitoring this list have any experience with eliminating interference from the comms for an IFR certified GPS? I have a Mooney with a KX-155 comm/nav and an Apollo SL40 comm that are both interfering with the Apollo GX50 GPS. The interference isn't coming from the antennas but the comms themselves. I suspect the local oscillator in the receiver IF stage, but don't know for sure. I seems like there should be a way to shield and/or ground the comms to eliminate the interference. Any assistance is greatly appreciated. Thanks, Lynn M. ________________________________ Message 2 _____________________________________ Time: 09:33:44 AM PST US From: HornetBall@aol.com Subject: Re: Avionics-List: GPS Interference from Comms --> Avionics-List message posted by: HornetBall@aol.com Make sure all of the antenna cables are in good shape and properly grounded (best to just replace them). Make sure the power wires and antenna cables are run in separate bundles and that all chasis are properly grounded. Check the KX155 first, it is the noisiest radio and probably also has the oldest wiring. With the wiring and grounds checked out, transmit on the following COM frequencies and watch for GPS drops: 121.15 121.175 121.2 131.25 131.275 131.3 If GPS drops occur, you're looking at adding chokes to the COM transmit antenna and/or moving the GPS antenna. All pretty standard stuff that a good avionics shop should be able to help with.