Northern Airborne Technology AA83-001 rev.4.10 - Manual (Page 14)

SM09-2 Rev. 4.10 AA83-001 InterMUSIC™ Stereo Intercom System Manual
2.3.2
Cautions
In all installations, use shielded cable exactly as shown and ground as indicated.
Significant problems may result from not following these guidelines.
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 microphone wiring and Tie Line wiring, as these lines carry the lowest level
signals in the aircraft.
All microphone and headset jacks should be electrically isolated from the airframe or
significant ground loop noise may result.
2.3.3 Cabling and Wiring
All unshielded wire should be to MIL-W-22759 or equivalent. For shielded wire
applications, use Tefzel MIL-C-27500 shielded wire with solder sleeves (for shield
terminations) to make the most compact and easily terminated interconnect. Follow the
wiring diagrams in Section 2.6 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. Aircraft harnessing should permit the unit to be lowered from the panel for
easy access to all side adjustments. Do NOT mount the unit until all adjustments have
been carried out.
All wiring should be at least 22 AWG, except power and ground lines, which should be
at least 20 AWG. Ensure that the ground connection is clean and well secured, and
that it shares no path with any electrically noisy aircraft accessories such as blowers,
turn and bank instruments or similar loads. Power to this unit must be supplied from a
separate breaker (1/2 A) or fuse (1/2 A fast), and not attached to any other existing
breaker without additional protection. The correct fuse is included with the AA83-001.
2.3.4
Installation Notes
All AA95/AMS4X Audio Controllers used with the AA83-001 must have the ICS Tie Line
and Gain Modifications installed. This will only be a concern on Audio Controllers with
S/N 1918 or before. If the AA83-001 is used with a second unit such as an AA82, you
may wish to install the 2.2 k
Ω resistor shown in the installation drawing. This is used to
equalize ICS Tie Line loading when changing from the tie to split connections. If you
are not familiar with Tie Line techniques, request the installation bulletin from NAT
covering Tie Line theory and practice.
Page 2-2 Oct 20, 2004
ENG-FORM: 805-0107.DOT
CONFIDENTIAL AND PROPRIETARY TO NORTHERN AIRBORNE TECHNOLOGY LTD.