Can I channel a HF transceiver through a Garmin 340 audio panel?

[Steve Ashby]

I am planning on installing a HF transceiver in my 8A. Most installations I have seen are pretty cobbled together with a hand held mic.
The Garmin GMA 340 has provisions for 3 coms. Does anyone know if I can channel the HF radio through the 340?
Thanks!
Steve Ashby

[N804RV]

Most basic radio transceivers interconnect 3 things with the audio panel/intercom: audio out (headphone audio), audio in (mic audio) and transmitter key-line.

The audio out and audio in have to be compatible. If the HF transceiver is an aviation type radio, compatible with the GMA 340, then no problem.

If it is not a compatible radio, then there will have to be some kind of interface adapter to match the audio signal of the HF to the intercom and the mic audio of the intercom to the HF. And, there may have to be a relay to indirectly control the HF key-line.

[GalinHdz]

Originally Posted by Steve Ashby

I am planning on installing a HF transceiver in my 8A. Most installations I have seen are pretty cobbled together with a hand held mic.
The Garmin GMA 340 has provisions for 3 coms. Does anyone know if I can channel the HF radio through the 340?
Thanks!
Steve Ashby

The short answer is "YES". The long answer is "it depends".

You have to make sure the transceiver to GM340 audio in/out impedances match and that is uses a ground to key the microphone circuit. Other than that, it is fairly straight forward.

[jnmeade]

I have a PS Engineering PMA8000C I will sell you. Never been used. (Somehow I bought two and don't need the other, although I'm building a plane and will use it if it's still around when panel time comes.) You need a radio adapter to go with it if you want to talk on your HF through your headset. My adapter is a 12100. Talk to Stein or Christer at SteinAir, they are the ones that helped me set up mine. They have good connections into PS Engineering.

[noelf]

Just a few comments:
If you are looking to use your aircraft as a "mobile" on the amiture radio bands, then adapting into the audio panel may be worthwhile.

If you are looking for a HF solution for long distance communications over water or similar environments, then a seperate HF radio independent from other aircraft equipment may be desirable. In this case, a separate HF radio, second dedicated headset and microphone, even a seperate standalone power source and trailing wire antenna ( or suitable fixed wire) and potentially an antenna coupler might make sense. Upon completion of this flight, the equipment could easily be removed from the aircraft.

[jnmeade]

A separate radio may be advisable for a trans-oceanic flight, but it has to be monitored is my understanding so that should be taken into consideration.

[Steve Ashby]

I definitely have trans-oceanic aspirations. I know some have converted an Icom ham setup to handle aircraft frequencies. I am just looking for a lightweight and affordable solution.

If possible, I would prefer using the HF through my headset, using an audio panel interface. Has anyone else done it?

Thanks!

[dpansier]

Not quite what your looking for but the same concept.
Yaesu microphone interface.

I plan to build one for my FT-817 with a small 3 element 432 MHz yagi bolted in the tie down thread.
Would be interested to see the capabilities on 432 SSB at ~8000 AGL.

[jnmeade]

I am most of the way there. I use the PSEngineering PMA8000C and the 12100 TAC radio adaptor. One has to match microphone impedances as the aviation and ham are not the same.
The radio is a Yaesu FT857D. I mounted it and a tuner on a flat plate and mounted the plate to the side of my aircraft in the baggage compartment. I put the detachable remote head on the panel. I used a circuit breaker on the panel and ran the power wire back to the radio, then ran the remote head cable back to the panel. Talk by selecting Com 3 and using the PTT, listen through the headset.
The antenna is not yet mounted. My Flight Design CTSW is carbon fiber so it does not provide a ground plane, therefore I elected to use a dipole which runs from each wingtip to the top of the vertical stabilizer and thence into the airplane and to the tuner.
It is hard to find through hardware that is not meant for ADF or similar applications. I got a thumb drive from Dayton-Granger that includes quite a range of antennas and accessories so although I didn't see exactly what I wanted, I got ideas from it. Although I'm experimental, I decided to stay fairly conventional. No trailing wires with guillotines etc. I've too much experience as a tow pilot to want a trailing wire unless it offers significant advantages. Of course, it lets you eliminate the tuner and simply run out the appropriate length of antenna, but you have to have a metal counterpoise which I don't have. Since some oceanic communication is on 40 meters (7Hhz band) it would be nice to have a longer antenna, but I don't expect to have to use that so I'll stick with 20m and higher. I'm just using it for my ham fun.
The Yaesu 857D just went out of production but there are still many around. The Icom 706 is another radio some use.

[Thermos]

Originally Posted by dpansier

I plan to build one for my FT-817 with a small 3 element 432 MHz yagi bolted in the tie down thread.
Would be interested to see the capabilities on 432 SSB at ~8000 AGL.

Don,

I'd love to hear more about how this works for you. Been thinking about a little airborne-mobile operation myself...but gotta get airborne first!

73

Dave