Ham radio integrated into the comm configuration

wrote in message
oups.com...
Want to combine my hobbies as I acquire a C-172 - has anyone mounted a
ham radio in their bird and wired it through the comm panel?

Yes. First one in 1968 was a Benton Harbor Lunchbox (vacuum tube "Twoer")
in a Cessna-120 using a dynamotor to supply plate voltage. Antenna was a
wire whip scotch-taped to the windshield and using the glareshield as a
ground plane. Didn't work worth a damn; that superregenerative AM receiver
knocked out every radio in the airplane and was damned noisy because of the
unshielded ignition.

Currently running a Kenwood TM231 through the audio panel. Antenna is a fat
wire whip out in the plastic wingtip using the last rib and the attached
wing as the ground plane. Works great. (see 73 Magazine "Ham Radio In The
Airplane" August 1981 for some practical tips on several ways I put the
radio into an aircraft.)



Problems?

I don't really care for the way I had to mickey-wire a couple of switches in
the audio panel, so I'm designing one that will be primarily for that
"third radio", be it amateur, CB, businessband, or what have you. The audio
out of the radio is no problem to mix and match, but the microphone is a bit
of a wicket. Aircraft microphones are "carbon compatible", which means that
they put out around half a volt with something on the order of 10
milliamperes of bias from the radio. Some ham rigs are plug-compatible, and
some require a bit of level matching to get it right. And, the ham rig (or
the matching network) needs to supply the aforementioned DC current to the
microphone.



Successes?

Mostly 100% after I got away from the AM superregen.

Suggest you get a copy of FAA Advisory Circular 20-98 (Auxiliary Two Way
Airborne Radio System Installations) and peruse it carefully. While it is
not a current circular, it is the latest circular on the subject and has not
been rescinded.

The most useful tool that you can lay your hands on for ham radio
installations in an aircraft is an A&P that is also a ham, or at least a
techie.


BTW, a wavelength at 250 GHz. is 0.05", not one inch.



Jim
WX6RST
Cessna 182 N 73 CQ