In most cases if you have a David Clark headset all you have to do is
change the mic to a civilian type. The electro fet M-7A is the desired
mic but the old M1 which is bigger will also work. It will just plug
right in to the same plug at the mic. You just have to loosen two set
screws at the mic to remove the plug.. I have some friends that used
to fly ex-military OH-58's and Bell 206 helicopters also and they
tywraped a second mic to the back of the military mic and would rotate
the mic around 180 degrees on the ball and socket mic mount on their
flight helmets and swap the mic plug to the other mic to change
between military and civilian aircraft. For fixed wing aircraft you
also need a single plug U-174/U to two plug adapter Y cable. Several
places sell these DC PN 18253G-05 including Sporties for about $40.
David Clark sells a dual impedance headset H10-66 that has a switch to
change between the mil and civilian types. The addition is an
internal mic amplifier PN 18911G-01 and a switch.

The mil mic is a 4 ohm impedance dynamic (no built in amp].
The civilian mic is a dynamic mic with an internal amplifier so that
it looks like an old style carbon mic, the amp is powered by the
radio.
The earphones are about 150 to 300 ohms in either case.
John F

On 26 Feb 2006 07:33:16 -0800, "Flyingmonk" wrote:

Thank you again VW'er,

Unfortunately, all talks of electronics fly right over my head.

Off on a slight tangent, I purchased two old military headsets that
have helicopter type plugs many years back. What do I need to get
these working (being compatible with civil radios)? Something about
the mic not being compatible was what I remembered, but I really need a
layman's term to understand. I fly choppers, so the one plug thingy
fits fine, no need to change to airplane's two plug type, just the mics
I think something with impedence?

The Monk