Pinging Jim Wier - X-Ponder Antenna Question

Jim,

Saturday coming back from Georgetown, DE to Somerset, NJ, no one, not Dover,
ACY or McGuire, could receive my transponder. We'd had this problem once
before, and our avionics guy suggested cleaning off the transponder antenna,
which is close enough to the engine on the Archer that it gets oily. It was
really dirty that time, and cleaning it seemed to work, so one of my
partners tried cleaning it again just before taking the plane up after I was
finished with it. He said that just a very small bit of oil came off the
antenna, but he then had no problem at all with the Wilkes-Barre TRSA seeing
him. Again this procedure seems to have worked.

My question is this: Does it seem reasonable that a very small amount of
oil on the antenna can effect transmission that much? Isn't even dirty
motor oil pretty non-conductive? Should we be looking more closely at the
antenna to see if it might have a loose connection that gets jostled from
the paper-towel wipedown?

--
Bob (Chief Pilot, White Knuckle Airways)

I don't have to like Bush and Cheney to love America