There have been cases of an intermediate frequency of transponders causing
this type of interference.

Jerry in NC

" jls" wrote in message
...
When I attach it to the yoke and put the antenna on the dash over the
panel,
it refuses to get any satellites--- none. Yet it works fine in another
172
and in a Taylorcraft -- and in all the other airplanes I've used it in.
Now why is that? It will work as long as the master and radios are not on
and the engine not running. It's a Trimble Flightmate Pro, ancient but
adequate for me. TIA for satisfaction of my burning curiosity.