On 10-Nov-2003, (Snowbird) wrote:

Well, but.. which is the good com? They both get the interference..

If you get the impression I'm not too thrilled about disconnecting
all the antennae in the plane, you got that right. Removing
avionics and leaving them on the ground is easy, for the most part
(and legal for me to do AFAIK).

Disconnecting some of our antennae is a cast-iron b**** and
reconnecting them is worse. Notably, the VOR/glideslope antennae.
Which brings me to ask...what does d/c'ing antennae get me that
removing their avionics doesn't?

I'm really hoping to hear from a couple of other folks on this
one, notably Jim Weir since I took his advice, drove to the antenna
farm, and found interference w/ my handheld.

What do you suggest next, Jim?


Sydney,

What your drive to the antenna farm (with the handheld) "proved" is that the
problem is still most likely garden variety intermodulation interference.

Sure, go ahead and pull your radios one at a time as Jim Weir suggests. My
guess is that you will still have the problem on the remaining radio(s).
This is because each radio is generating its own intermodulation products.
But PLEASE don't start yanking antennas. As you note, they are a b***h to
deal with, and it is EXTREMELY unlikely that they are the source of the
problem based upon the symptoms you describe.

Oh, by the way, something that I don't think has been covered in this thread
(and I admit I haven't read every post): Broadcast signals are often much
stronger in some directions (from the broadcast antenna) than others. So,
if you are doing repeated flying tests they should be conducted in the same
location, not just the same distance from the antenna farm.



Well, I did. I can't say they were "more than interested" in fact,
they were initially interested in telling me my equipment was at
fault because "we just had our equipment checked last Tuesday and
we're absolutely clean".

But I'm hopeful I eventually persuaded the guy I talked to
that if I could drive up to the foot of other antenna and just get
some strong RF noise on the aviation band, but drive up to the
foot of his tower stick the ducky out the window and listen to
a broadcast 5x5, maybe this bore investigation. At least he said
he'd call me back in a couple days and gave me his direct number.

I would be VERY surprised if the interfering signals are being generated at
the antenna farm. Of course, as they say, "nothing is impossible."
--
-Elliott Drucker