Z

ZorgroZ

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I?d like to be able to use a portable radio (such as the Yaesu 750L) in-flight at the same time as my airplane?s built-in radio / intercom. (Use cases: Air-to-air communications, or to listen to ATIS without having to ask AFIS for a temporary frequency change or changing from mountain frequency).

I guess just using a passive ?Y? cable adapter to plug my headset into both radios won?t probably cut it, due to impedance issues?

Does anybody know a suitable solution for this (commercial or DIY)?
 
A passive 'Y' almost works - but one radio may look like a short to the other. Build the Y in a small box, and insert 2 resistors, each about 470 ohms, one in each line leading to a radio. This will also cut the signal down, so you will need to be able to turn up the volumes (e.g., this won't work well if you already need full volume).
 
ZorgroZ said:
I?d like to be able to use a portable radio (such as the Yaesu 750L) in-flight at the same time as my airplane?s built-in radio / intercom. (Use cases: Air-to-air communications, or to listen to ATIS without having to ask AFIS for a temporary frequency change or changing from mountain frequency).

I guess just using a passive ?Y? cable adapter to plug my headset into both radios won?t probably cut it, due to impedance issues?

Does anybody know a suitable solution for this (commercial or DIY)?
Click to expand...

I have the same need.

My RV-8 is single com (Garmin 430 W) with only an intercom (PS Engineering) but no switchable audio panel. My handheld radio is Sporty's SP-400.

I use the Quite Technologies Halo stereo headset. The Halo has a little box with a 1/8" stereo jack which allows audio input for auxillary sound sources (Handheld radio's, music...).

Using an 1/8" jack adaptor, I can connect the handheld radio to my Halo headset jax and listen to both radio's at the same time.

The rubber ducky antenna on the Sporty's is less than optimal and could be enhanced by connecting it to a more robust antenna.

Bruce E. - Tanks for the "King KX-99 antenna adapter" tip. Do you use it?
 
Chkaharyer99 said:
Bruce E. - Tanks for the "King KX-99 antenna adapter" tip. Do you use it?
Click to expand...

I was going to purchase and install it, then never found myself lugging the handheld into the small cockpit.
I had my ICom radio go out on me below Seattle airspace. I flew home squawking 7600. Nice peaceful flight.
Now I have the Dynon radio...VFR only pilot and plane.

I did do Randy's pedal extensions but switched to Paul's http://www.vansairforce.com/community/showthread.php?t=121422
 
I built a similar thing some years ago into a portable intercom. You need to manage three signals: receive audio, transmit audio and ptt. The receive audio can probably by Y'd together through resistors as described by Bob Turner. You'll probably want a switch to select the panel or portable for transmit and ptt. By then it almost looks like an audio panel, although they usually have three radios selectable rather than 2.
 
Thanks for the suggestions.

So I need a resistor only in each of the two connections from the radio to my Y-box (i.e., receiving audio, going to my headphone), not the connections coming from my headset's mic and going to the two radios?

Each radio has its own PTT switch, so there's nothing required with regards to that, right?


NB. What would be cool though, is to combine the antenna selector (or even Y connection for antenna for simultaneous usage) with the box above, so that I can use the external antenna with my handheld.
 
Some panel mounted radios have a monitor function that allows listening to two frequencies at once.
 
I think most people would recommend a switch for the mike, so it goes to radio #1 or radio #2. It may work okay wired to both, or not. It depends on what's inside those radios.
Switching coaxial antenna cables is tricky. You would like to maintain the 50 ohm impedance continuously, with no 'bumps'.
 
Sounded like you were more interested in listening than talking on the second radio. If that is the case, you probably will not gain much with an external antenna for ATIS. Line of site will probably give you good performance.
As a back up radio, many of us keep headset adapter plugs attached to a handheld (and alkaline batteries since they store well) in the plane.
Also of note, the ICOM radios allow you to monitor ATIS and the primary freq. at the same time. (almost) It does a sampling scan back function every few milliseconds.
Good luck with your project.
 
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