Northern Airborne Technology AA95-766 - Manual (Page 15)

SM95-766 Rev. 2.00 AA95-766 Single Channel Audio Controller Manual
inputs/outputs of the AA95-766, a method of controlling the microphone on the headset
is needed because of the 'hot mic' circuitry. This is best accomplished with a 'mic
interrupt' switch in the PTT cordset.
There are numerous manufacturers of in-line PTT cordsets, offering many 'electrical'
variations to accomplish different functions. To meet the operational requirements for
headset stations supported by the AA95-766, NAT recommend the dual switch type: a
3-position (momentary/center-off/locking) slider switch for the ICS functions, and a
momentary, push-button switch for the Transmit functions. Both switches provide a ‘mic
interrupt’ function. The 3-position ICS switch will allow the user to change the switch
settings to match the operational intercom mode that has been selected (e.g., LIVE,
KEYED or VOX). The cable should have 6 conductors, with the MIC and PHONE pairs
shielded (MIC wires must be shielded as a minimum). To ensure proper shielding, the
shield(s) should be terminated to the MIC LO connection at the airframe connector of
the PTT cordset. See the drawing below for details.
To avoid complications in the aircraft, it is recommended that the same type of PTT
cordsets be used for all headset locations in the aircraft. It is not good practice to create
a situation where a specific cordset is needed for the copilot, which might cause
operational errors if moved to a passenger location.
Dec 6, 2004 Page 2-5
ENG-FORM: 805-0106.DOT
CONFIDENTIAL AND PROPRIETARY TO NORTHERN AIRBORNE TECHNOLOGY LTD.