Ultralight to gA headset adapter

[DrSky]

I have a helmet that was wired for ultralight (single plug). I bought an adapter to be able to use it in my experimental which has dual plugs, standard GA arrangements. I can hear fine but there must be some impedance mis-match with the mic because others cannot understand what I transmit. I carefully removed the casing on the adapter and see at least one resister. Anyone know any way to figure this out and perhaps swap out a resister or something to get this to work.
BTW my general aviation headset works fine in the experimental.
I used Jim Weir's circuit from kit planes, I think the mic works, the amplitude of the signal it generates seems to be way too low.
Strangely I am unable to find a circuit diagram for this adapter. Must be top secret...

 

[Archammer]

I'm having trouble determining where your failure is. From what I'm reading, I believe that it is the adapter or your circuit. Your helmet should already be high impedance because it's not a military helmet right? What brand of ultralight helmet?

If it's something like a Lynx or Comtronics helmet that uses a lemo plug (7-pin), you have to buy the twin jack adapter for that helmet. But you shouldn't have to change the microphone as it should already be high impedance.

Give me some brand names and/or part numbers of the helmet and the adapter, and some more detail on this circuit you built and we'll go from there.

We'll get you all sorted out.

 

[DrSky]

Shane, thanks for the reply.

No, it is not a military helmet, I think I accidentally ordered, or was accidentally sent, the ultra-light version instead of the GA version. I do not remember who I actually bought it from. It is a Fulmer AF155. The adapter that they sent to rectify the problem does not have a brand or anything just a printed label that says:

UL to GA (E)

I owned both for a while before my experimental was ready to fly so I did not realize I had a problem with this until recently.

 

[DrSky]

Oh, the circuit I am talking about was from the article Jim Weir wrote for Kitplanes a couple of years back. I was reminded of it because he referenced it in the most recent KitPlanes Aero-electrics column. It just uses a 9volt source, a resister and a capacitor to allow you to hook your mic to your earphones to do a quick self test. I actually was also looking at the signal produced on my little hand-held oscilloscope. That was how I could tell the mic was active, a much smaller amplitude than my sigtronics headset produced in the same circuit.