Northern Airborne Technology AA12 - Manual (Page 12)

AA12 Compact Audio Controller Manual SM21 Rev. 4.10
2.3.2
Cautions
In all installations, use shielded cable exactly as shown and ground as indicated.
Significant problems could result from not following these guidelines.
Shield and route the microphone (MIC) and ICS tie lines used in the AA12 installation
appropriately. Not doing this can result in poor performance of the aircraft audio system.
The operation of the VOX intercom can be severely degraded by mixing different
manufacturer's microphones in the aircraft intercom system. NAT recommends that all
microphones be identical for optimum performance of the ICS VOX intercom
All audio installations can be seriously degraded by incorrect wiring and shielding, and
may result in abnormal cross-talk, hum and ground-loop noise. Be especially careful
with all MIC wiring and Tie Line wiring, as these lines carry the lowest level signals in
the aircraft.
All MIC and headset jacks should be electrically isolated from the airframe or significant
ground loop noise may result.
2.3.3
Notes
Audio performance can be impaired by the introduction of airframe electrical noise at
the headset jack locations. For best results, all headset jacks should be fully isolated
from the airframe.
2.3.4
Cabling and Wiring
All unshielded wire should be MIL-W-22759 or equivalent. For shielded wire
applications, use Tefzel MIL-C-27500 or Mil-M81044 single conductor and shielded wire
with solder sleeves (for shield terminations) to make the most compact and easily
terminated interconnect. Follow the wiring diagrams in Section 2.4 as required.
Allow 3 inches from the end of the wire to the shield termination to allow the hood to be
easily installed. Note that the hood is a “clamshell” hood, and is installed after the
wiring is complete.
All wiring should be at least 22 AWG except power and ground lines which should be at
least 20 AWG. Ensure that all ground connections are clean and well secured.
Page 2-2 Sep 9, 2004
ENG-FORM: 805-0106.DOT
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