"Rich S." writes:

I think we'd best look elsewhere for the solution.

Sounds like intermodulation to me. Look for a sum/difference with the
frequencies at the antenna farm?

I'd ask other owners. Then try to find your regional FAA frequency
coordinator or similar, in other to locate a sympathetic ear. He'd
know who would go by with a 494 spectrum analyzer or such...iffen they
ever have time.

It could well be intermod from tower guy joints or such. It could
also be the front end of the radios. (Don't suppose you have 3 element
cavity tha would fit in the back seat ;-?)

If all else fails, maybe filing a NASA report would get a response.
--
A host is a host from coast to
& no one will talk to a host that's close........[v].(301) 56-LINUX
Unless the host (that isn't close).........................pob 1433
is busy, hung or dead....................................20915-1433