Cessna 182: VOR/LOC/GS issues
Hi everyone,
I have a 2001 Cessna 182T in which I have installed a Garmin GTN 750 and 650 as my nav/comm units. They're great, but I'm having a problem with the ground-based navigation that my mechanic and avionics guy have been unable to solve. I'm hoping that someone here might be able to point me in the right direction.
Here's the issue: when I tune in a VOR or ILS, the needles oscillate. The closer I am to the station, the more the oscillation is. We've checked all the antenna wiring and it's fine. This occurs with both nav/comms, although strangely the 650 is less susceptible than the 750. It's particularly bad when flying an ILS - the needles do a "hula hoop" dance around the central circle.
The theories so far (and the reasons why they are hard to believe) are:
- Antenna problem (The plane is a 2001 and that's not really very old in aviation terms)
- Alternator issue (charging system seems fine)
- Noise supressor (yet I'm not hearing anything on the intercom and the com radios are clear)
- Antenna wiring breakout (this apparently only fails catastrophically according to my avionics guy)
So we're all stumped. Does anyone have any ideas?