Thanks for the reply Chris. Sorry for delayed response, wasn't near a computer. Yes, this is essentially going to be a short version of the long comm cord used by helo crew chiefs when they dismount from the aircraft. In this case I'm using aviation and/or similar compatible headsets plugged into a handheld radio (think MBITR) and I need a PTT switch. In this case, I'm attaching the cord and 174 plug from a pilot's helmet to the U-94 PTT because the pilot's cord is thinner, cloth and flexible. Easier to wrangle around all the crap molled onto my body armor. It will be a few days till I can plug into a SINGARS, MBITR, or helicopter; and of course that's when I'll need this thing to work. (yes, I'll have the different QD adaptors when I get there.)
I had found most of the schematics you gave me links for but with no real electrician skills to speak of I was just swimming. I do appreciate the links though, putting them together helped me figure a couple other details out. But I found a lot of other schematics that seemed to contradict each other, like these two (don't remember where I saw it but it was opposite the one on the left.):
The mechanics I can handle. I can make very solid splice connections using pin sleeve connectors and I can solder. I can make a splice as strong and durable as an electrician. I just need to be sure the invisible juice is flowing proper.
I had tried through experimentation to use batteries for power source but all I could be sure of is that I had static in the phones and I could hear the PTT break squelch. So yesterday I disassembled an old handheld and attached leads from the plug pins to the two wire speaker. It worked, I could send to, and receive from another radio. But in order to transmit I had to use the PTT on the handheld. It didn't matter whether I used the headset's U-94 PTT or not, when I keyed the handheld it transmitted. So I was sure everything worked but couldn't be certain about the U-94 PTT.
So, I had figured out (duh) that the extra white and black leads on the pilot's plug are for the seperate speakers that would have been in the helmet; and for what I'm doing they're redundant. (As you said also) And I'm assuming the plug on the David Clark headset has only one lead per tab because the "Y" junction for the seperate speaker is farther up the line in the first speaker housing. Still stumped why the plug pin locations seem different than the pilot's plug, but to hell with it, it works. The pin locations on the plug and PTT match so I'm just going color to color on those leads. So, the only thing left is where do I stick that yellow bugger? I'm assuming it should be spliced with the white leads from each cord.
David Clark Headset schematic: