Model 245 Speaker Amplifier Manual
SM245 Rev. 4.10
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, especially with
regard to ground loop noise.
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 3 inches from the end of the wire to the shield termination to allow the backshell to
be easily installed.
2.3.3.2
Pin Identification
The following table specifies the functions of the connector pins.
PIN # FUNCTION
A
+ SIGNAL INPUT
B
SIGNAL GROUND
C
- SIGNAL INPUT
D
- OUTPUT
E
+ OUTPUT
F
POWER GROUND
G
+ 28 VDC IN
Connection to the unit should be made with twisted pair, shielded cable. The shield
should be attached to the airframe at one end only. Pins A, B, and C (the input pins)
should be wired using 22 - 24 AWG wire. The output (pins D and E) and power (pins F
and G) should be wired using wire no smaller than 20 AWG.
The finish on the case is electrically conductive, and it is not necessary to remove the
finish for electrical bonding.
Caution: do not connect the audio outputs to power return or chassis ground.
2.3.4
Mechanical Installation
The Model 245 may be mounted in any position. No shock or vibration isolators are
required.
For proper heat dissipation, the Model 245 should be mounted on a metal surface of at
least 100 square inches. The amplifier case should also be grounded to the airframe.
Page 2-2
Jun
2
3, 2005
ENG-FORM: 805-0108.DOT
CONFIDENTIAL AND PROPRIETARY TO NORTHERN AIRBORNE TECHNOLOGY LTD.
