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been rescinded.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

Hi George,

I would have to do that if I was going to operate in the HF realm (30
MHz and below), but I want to use a 2m radio and that will just be a
19" vertical on the top of the plane.

Don

Jay,

Did you have any problems with the display being overly bright at
night?

I'm thinking a Kenwood TM-255A with the body behind the baggage
compartment (short coax run to a quarter wave vertical) and the head up
front.

Thanks for the info on the KMA28, it sounds just like what I'm looking
for.

And since my A&P is a ham ...

Don, NL7CO

Before you mount the antenna on the top of the plane, think about your
radiation pattern. The radiation pattern of a moderately swept (i.e. "bent
back" to look sexy) whip over a large ground plane (like an airframe) is
like cutting a grapefruit in half and skewering it with the whip. Note most
of the radiation going UP away from the whip.

Now think about who you are going to talk to. Astronauts in space or ground
based hams? The point is that an antenna on the belly is a LOT more
efficient in getting your radiated power where you want it.

Now a practical matter. Some day you are going to want to sell that
airplane. An airplane with a ham radio antenna on it may not be attractive
to a potential buyer. However, if you go down to the airplane junkyard and
buy a used inspection plate, bring it home and paint it to match the
fuselage, take the REAL painted inspection plate off and put it in a safe
place, then mount the ham antenna onto the paint-to-match junker inspection
plate, you have a removable antenna when the time comes. Just take the ham
antenna off and put the "real" inspection plate back onto the fuselage.

(For those of you who are mounting GPS antennas, don't make the opposite
mistake. I was doing a plans check for one of the locals the other day and
he had the GPS antenna mounted on the belly. Damned few GPS satellites
below you at the altitudes most of us fly at.)

Jim


wrote in message
oups.com...
Hi George,

I would have to do that if I was going to operate in the HF realm (30
MHz and below), but I want to use a 2m radio and that will just be a
19" vertical on the top of the plane.

Don

"RST Engineering" writes:

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.

Feature Request:

Please include artificial sidetone, since most ham rigs don't provide it
in any of the phone modes.

That's the only "fix" I need to do for my installation, to provide
artificial sidetone.

-jav

" writes:

Did you have any problems with the display being overly bright at
night?

Nope. I've an Icom IC207H, the display is a pleasant amber color.

I'm thinking a Kenwood TM-255A with the body behind the baggage
compartment (short coax run to a quarter wave vertical) and the head up
front.

That's exactly how I installed mine, the RF deck is on the equipment
shelf just aft of the baggage area, then I ran the umbilical cord
under the floorboards, along with all the other existing wires, and
mounted the control head on the panel.

Thanks for the info on the KMA28, it sounds just like what I'm looking
for.

And since my A&P is a ham ...

That's 75% of the battle.

-jav