Karl-Heinz Künzel wrote:
jan olieslagers schrieb:
I recently acquired a couple of Peltor 8003 headsets secondhand. They
have two stereo jacks. These are molded on so I cannot open them up to
see what happens inside.

I took the quarter-inch to be stereo, but no: I measured some 290 ohms
from tip to ground, and nothing between ring and ground. And indeed a
signal on the tip will be heard on both sides. Is anything wired to
the ring? If not, why did they bother to use a stereo jack?

I'm still more baffled by the microphone jack: perhaps the ring is a
provision for a PTT-switch?

Thanks in advance for any enlightenment,

From Peltor.se:

The Aviation 8003 headset for winged aircraft has an ambientnoise
compensated dynamic differential microphone, specially
designed for aviation intercom systems
The microphone amplifier can be adjusted for output signals in
the range of 300-600 mV
The frequency range is adjusted for good speech
recognition
The straight polyurethane cable with moulded connectors has
a stereo/mono switch in the branching box
The earphones have a 1/4� stereo connector and the microphone
has a PJ068 connector.
The Aviation 8006 headset for winged aircraft has an ambientnoise
compensated electret differential microphone, specially
designed for aviation intercom systems
The microphone amplifier can be adjusted for output signals in
the range of 300-600 mV
The frequency range is adjusted for good speech recognition
The earphones have a broad frequency range for good sound
reproduction
The straight polyurethane cable with moulded connectors has
a stereo/mono switch in the branching box
The earphones have a 1/4� stereo connector and the microphone
has a PJ068 connector.

KH
As indicated above, try flipping the switch & re-check the
ring-to-sleeve impedance.

'Standard' aviation mic plug/jack wiring is:

tip=PTT(push to talk switching for transmitter)
ring=mic 'high' (audio)
sleeve=ground (for both PTT and audio)

Pressing the PTT button ties the tip to ground, pulling the transmit pin
on the radio's connector to ground, activating transmit in the radio.

Charlie