[JohnBHanson]

U-174/U (TP-101)
HELICOPTER HEADSET / HELMET PLUG
. This is NOT a NATO plug, it is a NEXUS plug (sometimes referred to as a US NATO plug) and it is not compatible with the UK NATO plug below. TheU-93/A (TP-102)plug is the same mating shaft with a larger back shell for thicker cable. Wiring,
Tip(1) Mic low (2) Ear high (3) Mic high (4) Ear low


PLUG 671
UK or EUROPEAN NATO PLUG
This plug will not mate with the Nexus range, the mating shaft diameter is 0.4mm bigger. This is a Mil spec brass plug, NSN:5935-99-946-6652. Wiring, Tip Mic, Ring 1 Mic, Ring 2 Ear, Ring 3 Ear, (Ring 1 next to tip) Mating socket, Socket 626, NSN:5935-99-949-1940

or
US Nato (silver)
Tip 1 Mic ground
2 Audio +
3 Mic +
4 Audio ground

UK Nato (bronze)
Tip 1 Mic +
2 Mic Ground
3 Audio +
4 Audio ground