Sennheiser NoiseGard HMDC 322 Instructions For Use Manual page 54

Connecting the headset, turning on the battery pack
Connect the XLR-3 plug of the headset connecting cable to the XLR-3 socket on the
connecting cable of the battery pack.
HMEC 300 and HMEC 400 headsets: Connect the ¼" (6.35 mm) stereo jack plug for
the headphones and the PJ-068 jack plug for the microphone to the corresponding
jack sockets of your intercom.
HMEC 305-C headset: Connect the XLR-5 plug for the headphones and the
microphone to the aircraft's XLR-5 socket.
HMEC 322 and HMDC 322 headsets: Connect the U-174/U jack plug for the
headphones and the microphone to the U-174/U socket of your intercom.
Turn on the battery pack by setting the ON/OFF switch to ON. The green LED power
indicator lights up.
Note:
When using the battery pack, the ON/OFF switch integrated into the headset
connecting cable is out of operation.
Attaching the battery pack to clothing
The battery pack can be attached to clothing by means of the supplied attachment clip,
Velcro tape is also supplied.
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