Finally fixed that nagging glideslope drift after 3 months of head scratching

I was out at KPDK last Friday troubleshooting a Garmin G600 that kept showing a 0.2 dot glideslope offset on approach. The shop manual said check the antenna cable but we had already replaced it twice. Turns out the coax was pinched under a seat track rail from a previous install, just enough to shift the signal a tiny bit. I pulled the floor panel, rerouted the cable with some adhesive clamps, and now it holds steady through the whole ILS. Has anyone else found weird RF issues from hidden cable damage like this?

3 comments

3 Comments

adams.uma16d ago

Oh wow, that is a sneaky one. I had a similar thing on a King Air a few years back with the radar altimeter. The cable looked perfect on the outside but was crushed flat under a floor panel where someone had stepped on it. It would work fine on the ground but give erratic readings in flight. Took me two weeks to find it. Those coax runs are way more fragile than people give them credit for.

corap2116d ago

Isn't it wild how the most obvious stuff is always the hardest to see?

kimfisher16d ago

Did you read Mike Busch's column about crushed coax in the latest issue?