RF interference issue again (esp. for E Drucker and Jim Weir and other RF wizards)

Aaron Coolidge wrote in message ...

Sydney, have a look at the fcc link I posted a couple messages ago. It lets
you look up towers' owners by lat/long. Your tower is owned by KTVI chan 2.

Thanks.

: Do other aircraft report the same interference?

: Not that I've heard, but then, I might not have heard.
: Or, like us, they might have assumed it was a problem in
: their airplane.

Update: I talked to a local DE who is also doing piles of
instrument instruction. She says she's flying in beaucoup
planes in that area, without the same problem.

So it *is* something specific to our plane I guess.
Although it's an intermittant problem for us, too.

: We didn't have this problem before last spring.

Did channel 2 recently add a digital TV transmitter? Like, last spring?

I believe so, yes.

So here's what I'm thinking.

That tower is TV Channel 2 (60-65 MHz I think?)
Channel 5 which is nearby would be 79-84 MHz.

This makes me think that marker beacons, at 75 MHz,
are the logical suspect for causing a problem.

But can the marker beacon antenna, by itself, be somehow
bringing signals into the plane to be received by the
rubber whip antenna of our handheld?

If this is a possibility, how do we safely remove the
marker beacon antenna for testing purposes? Do we need
to put some kind of load on the cable heading for the
marker beacon receiver, since we can't turn the MB off
while the power in the plane is on?

If removing the MB antenna seems to cure the problem,
what do we test or do? Is the antenna itself likely to
be bad and in need of replacement, or is this likely to
be a ground type issue where maybe we should replace the
coax, or at least redo the connections?

If it seems far-fetched that the MB antenna itself is
the culprit, where next do we look?

Thanks,
Sydney