LettersFromFlyoverCountry

LettersFromFlyoverCountry

Well Known Member
One of our reporters in Fargo (OK, our ONLY reporter in Fargo) was up in a Border Patrol helicopter the other day. Usually,when he goes in a plane or helicopter, he has a little contraption that he uses to record conversations with the pilots etc., (you can't use a regular microphone in an airplane as I'm sure you know).

He called me today to ask if there's more than one "standard" for headset jacks in aviation? I told him the only standard I know of is established by the marketplace, where headset manufacturers want their products to be used across as many aircraft as possible.

But he said he couldn't use his contraption because the jack was different in the helicopter. Shorter with "multiple rings," he said.

Is there a different "standard" for military aircraft?
 
The difference, what I understand, is that the military uses low impedence jacks and we use high impedence (or vice versa). I used a military headset during my student days and needed an adaptor in order to convert the impedence and also to convert the one jack on the headset to two jacks for the skyhawk. The adaptor is available through ACS.

This info may be totally wrong, but gives you a place to start.
 
Bob Collins said:
Is there a different "standard" for military aircraft?
Click to expand...

Well, there are a couple of "standards" for military aircraft, but what your friend found (the single, shorter plug with more rings) is pretty standard for helicopters in my experince....and don't ask me why!

A few weeks back, with that great thread on the DIY lightweight headset, someone asked why bother with aircraft jacks - why not just use the mini's that come with headsets today? The answer for me is standardization - what happens if you are a long way from home and your headset quits - and you have to borrow one? You want plug and play, and as ancient as our civilian-standard, two plug system is, it is least "fairly" consistent....

Paul
 
Generally speaking, civilian fixed wing aircraft have the two standard plugs that we are all familiar with (they are called the PJ-055 and PJ-068). Civilian helicopters and most military aircraft (fixed wing and rotorcraft) use a single U-174/U plug. The impedance, however, can vary between the civilian and military U-174/U setups. Then, the Airbus uses something entirely different. You can get adapters to go from just about anything to anything else. You can go from (shameless plug follows...) fixed wing to helicopter, helicopter to fixed wing, low to high impedance, or fixed wing to Airbus.

Corbin Glowacki
MyPilotStore.com
RV-6A
 
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Bob Collins said:
those links aren't working for me, Corbin
Click to expand...
Bob, you can get it to work by stripping out the extra "http//" after the "http://" in your browser URL box. In these forums that extra stuff is put in by default so if you put the entire link after that it doesn't work.

I didn't make that very clear did I?
 
DIY Adapter?

Along the lines of this post but a little OT...

Would it be fairly easy to roll my own adapter? I have a great headset from my day job that has the military plug and I'd like to use it when flying GA - without paying $75 for an adapter. How big of a deal is the impedance issue? The headset is a Bose X, and from reading the documentation with it I can't tell that there is anything different between the one I have and the normal version, other than the plug. If the impedance issue isn't a big deal then I don't see why it wouldn't be easy to make my own adapter.
 
Impedance

Military audio panels use low impedance for both mic (5 ohm) and phone (8 ohm). Civilian audio systems are 150 OHM for mic and 600 ohms for phone. If you plug one type into the other, the audio will be either really low, or loud and distorted. The only "EASY" way I know off to make an adapter is using impedance matching transformers. A more elegant (read complicated) solution is to use op amps, but that would require a battery. It can be done, but unless your time is not that valuable, $75 is not that bad. If you do want to roll your own, it would look at mouser electronics for some transformers.
 
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Darn. In my simplistic view of electronics it all seems so simple...hah. In any case, $75 isn't much to pay to be able to use the Bose.

Now I'm going to go read up on basic electronics... :D
 
Bob
The short thick multi ring one is calles a "NATO" plug. Beleive it or not there is a US NATO plug and a British NATO plug and surprise surprise as far as I know they are not interchangeable (I stand to be corrected). From memory one is silver and one gold coloured on the rings.
John
 
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