Northern Airborne Technology 3110 - Manual (Page 24)

3110-100 Audio Control Panel Manual SM3110 Rev. 4.00
2.3.2
Cautions
Do not bundle any lines from this unit with transmitter coax lines. Do not bundle any
audio or DC power lines from this unit with 400 Hz synchro wiring or AC power lines. Do
not position this unit or wiring from this unit next to any device with a strong alternating
magnetic field such as an inverter, or significant audio interference will result.
In all installations, use shielded cable exactly as shown and ground as indicated. Significant
ground loop and noise problems may result from not following these guidelines. Ensure
that the chassis is grounded to provide proper shield terminations.
Ensure the microphone and headphone jacks are isolated from the airframe ground.
Use caution when routing microphone wiring, as it carries low-level signals prone to
coupling from other sources.
Do not take a ground from the instrument panel or similar location that shares a ground
return with a turn and bank, horizon or other motor driven instrument. This may cause
the unit to pick up the sound of the motor as ground loop interference.
2.3.3
Cabling and Wiring
All unshielded wire shall be selected in accordance with AC43.13-1B Change 1,
Paragraphs 11-76 through 11-78. Wire types should be to MIL-W-22759 as specified in
AC43.13-1B Change 1, Paragraphs 11-85, 11-86, and listed in Table 11-11. 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 three inches from the end of the wire to the shield termination to allow the
backshell to be easily installed.
All wiring should be 24 AWG unless otherwise specified. Ensure that all ground
connections are clean and well secured.
2.3.4 Mounting
No shock or vibration isolators are required for mounting. The unit should be mounted to
a metal surface and grounded to the aircraft ground structure. The unit and mounting
surface have an electrically conductive finish, which should not be removed for electrical
bonding to any metal aircraft ground structure because the finish prevents corrosion.
The unit should be convection cooled - no moving air is required on the case surface.
Page 2-2 Aug 25, 2005
ENG-FORM: 805-0107.DOT
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