All,

Thanks for all the suggestions, advice and information. I learned a lot
about VHF that I didn't know. Should have stayed with it way back when I
almost finished my "Novice" amateur license (couldn't manage the Morse code
part -- I guess that gives away my age).

Fred nailed it, although by the time I saw his note, I'd solved the problem.
After relocating the receiver as far away as I could (60 feet, given the
limitation of where the units needed to be and sources of power) which
didn't really help, I tried some simple filters, etc. During the course of
this, someone keyed a mike while I had the antenna disconnected, and it
worked fine with no antenna connected! A bit more experimentation indicated
that the 120.6 interference dropped out completely while the desired 123
signal could still be picked up from five miles away if I left the short
coax jumper inside the box from the receiver to the antenna disconnected at
the antenna end. I'm not sure I fully understand why I still get a pretty
robust signal this way, but I guess enough 123 MHz RF is leaking in from the
bare antenna or all the other wiring. Since the radio traffic of interest
is mostly local planes near the airport or in the traffic pattern, a five
mile radius is probably more than adequate, and this is certainly the
cheapest solution.

I will also look into the regulations about rebroadcasting non-commercial
radio signals. The transmitter satisfies the part 15(IIRC?) FCC reg about a
100-foot reception limit, but I thought the rules about rebroadcasting were
to prevent commercial rebroadcasting. The 100 foot limitation will keep
all reception on the airport grounds, but I will do some more research on
this. Thanks.

As far as an area inside the building where people can listen to the radio
is concerned, we already have that. This project is for the people who sit
in their cars in the parking lot and watch the planes on their lunch hour,
etc. We get quite a few of these. Anything that improves relations with
the general public should help alleviate some of the problems we have with
the neighbors. I still can't understand how anyone can buy a house near an
airport, and then feel that they have a right to complain about airplane
noise. The airport has been there since 1946, but that's another issue.

Again, thanks for all the help.

--
Bob (Chief Pilot, White Knuckle Airways)


"Fred McKenzie" wrote in message
...
In article , "Bob Chilcoat"
wrote:

Unfortunately, while this setup worked perfectly at home well away from
the
airport, we have an Automatic Weather Observation Station (AWOS)
transmitting continuously on 120.60 MHz only 50-60 feet from the place I
need to site the receiver. Even though this is only a 5 Watt
transmitter,
it overloads the front end of the receiver. As soon as anyone keys on
123.00 and the automatic squelch is triggered, all you hear is the AWOS
recording.

Bob-

By now you have probably solved your problem. If not, someone else
suggested that you insert attenuation in the Sony's antenna lead. I think
that approach is most likely to produce the results you want.

If you were to replace the Sony's antenna with a dummy load, there may
still be sufficient signal bleeding into the radio to make your system
work. The interfering signal would also bleed into the radio, but at such
a low level that the Sony's tuned circuits ought to be able to handle it.

If even this does not solve the interference, you may find the problem to
be audio rectification inside the 88.1 equipment, perhaps in the
oscillator stage!

Please keep us informed of what it takes to make it work.

73, Fred, K4DII