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

Steve Ashby

Well Known Member
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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
 
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.
 
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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.

:cool:
 
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.
 
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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.
 
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.
 
Trying to figure out how to integrate HF into the cockpit

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!
 
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.

oNS.jpg
 
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.
 
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
 
HF Radio

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

Good Morning Steve,

This should be something you can work out with a range of HF radios. Do you have one in mind that you are interested in using? It is not likely that received audio will be much of a problem, but the mic signal voltage levels can be tricky. Send us over which HF radio you are thinking about using and we would be happy to work to make a determination of compatibility for you.

Thanks,

Justin
 
Thank you all for your incredible help!

I am blown away by the generous input of you brother RVers. This is all valuable information.

I am buying a GMA 340 and I will be on the hunt for an adaptable and affordable HF transceiver for planned transoceanic flights. I am grossly ignorant of avionics installations, but, with the right help, I know I can make it all work.

Thanks again,

Steve
 
I am blown away by the generous input of you brother RVers. This is all valuable information.

I am buying a GMA 340 and I will be on the hunt for an adaptable and affordable HF transceiver for planned transoceanic flights. I am grossly ignorant of avionics installations, but, with the right help, I know I can make it all work.

Thanks again,

Steve
Once you decide which actual transceiver you want to use, then you can work on the rest of the design. It isn't superbly hard to do, just takes a little experimental aviation ingenuity.

:cool:
 
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.

Howdy all,

first post here after watching for a great many years!

I know this thread has been resting a little in the last year or so.

There is another choice for an adapter if you don't want to use the "Tactical Radio Interface" by PS Engineering. (about $700 from Aircraft Spruce and other places)

The Northern Airborne Technology AA34-100/200/300 Universal Radio Interface is a great alternative and seems to be very popular with float plane operators that want to interface their marine VHF FM equipment into their audio switching panels.

Here's a link to manualslib where you can read the install manual and specs etc:

https://www.manualslib.com/manual/1385448/Nat-Aa34-200.html#product-AA34-300

A local avionics shop owner told me that he has installed a great many of these things in float planes in the Pacific NW over the years.

I decided to use it in my 108-2 Stinson to install a dual band VHF/UHF amateur transceiver. It can be used with virtually any non-aircraft radio and allows a seamless interface complete with sidetone etc.

I recently found one online new (old stock) for about $300 and a whole bunch of "as removed" ones for less.

I've been operating amateur radio equipment in small airplanes since the 70's and (already installed) HF SSB equipment in USAF and civilian aircraft since the early 80's until I retired in 2018.

The only main problem with HF equipment in small airplanes is the short antenna. If you can cobble together a trailing wire using an end fed coupler (like the SGC-230, ICOM AH-4, and a host of others) It can work pretty well.

If you're stuck with a very short antenna like a repurposed ADF sense antenna, and running 100-150W, it's not going to work all that well on the lower medium and high frequencies. (below around 8MHz)

Even the Airline and military radios didn't work all that well on the lower frequencies with the crummy vertical stab embedded antennas but they made up for it with high transmit power (400W) And for the record, high altitude doesn't help all that much at all with HF skywave propagation.

Steve Ashby
Thank you all for your incredible help!
I am blown away by the generous input of you brother RVers. This is all valuable information.

I am buying a GMA 340 and I will be on the hunt for an adaptable and affordable HF transceiver for planned transoceanic flights. I am grossly ignorant of avionics installations, but, with the right help, I know I can make it all work.

Thanks again,

Steve

Steve,

there's several radios out there for ham radio that will "work" . I am not sure how the FCC would see it but most of the current stuff is certainly stable enough.

Other choices can be the Motorola MICOM-3T, Vertex Standard VX-1400/1700 and the ICOM IC-M802 and 803

The with the exceptions of the ICOM radios mentioned above, the others are discontinued but are available for reasonable prices (I have a VX-1700, IC-M802 and a Micom-3T and they're outstanding HF radios)

My choice would be the ICOM IC-M803 which is currently in production or even the MICOM-3T because they're commercial quality equipment. (and they have remote mounted control heads)

Anyway, there you go!

Please post back here with what you finally do! I would love to hear what worked for you!

73 All!

Rick
 
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