Northern Airborne Technology 246 - Manual (Page 8)

Model 246 Isolation Amplifier
SM246 Installation and Operation Manual
Section 2 Rev: 1.00 Issue 2 Page 2-2
ENG-FORM: 805-0115.DOT
CONFIDENTIAL AND PROPRIETARY TO NORTHERN AIRBORNE TECHNOLOGY LTD.
2.4.2 Cautions
CAUTION:
In all installations, use shielded cable exactly as shown, and ground only as
indicated. Significant problems may result from not following these guidelines.
Failure to follow the installation and wiring instructions provided in this manual
for power and ground connections, including the rating of the circuit breaker,
may lead to damage in the power input circuitry of the unit.
2.4.3 Cabling and Wiring
All wire shall be selected in accordance with the original aircraft manufacturer's Maintenance Instructions
or AC43.13-1B Change 1, Paragraphs 11-76 through 11-78. Unshielded wire types shall qualify 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 connector map in
Section 2.7 as required.
Allow 3" from the end of the shielded wiring to the shield termination to allow the connector hood to be
easily installed. Reference the interconnect drawing in Section 2.7 for shield termination details.
Maintain wire segregation and route wiring in accordance with the original aircraft manufacturer's
Maintenance Instructions.
The input pins (A, B, and C) should be wired using 22 to 24 AWG shielded
cable. The shield is attached to the airframe at one end only.
The output pins (D and E) and power pins (F and G) should be wired using wire no smaller than 20 AWG.
Reference the Interconnect drawings for additional specifications. Check 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
circuit breaker or fuse (fast blow), and not attached to any other circuit breaker without additional
protection. Verify that the selected circuit breaker size and wire gauge are adequate for the installation
using the techniques specified in AC43.13-1B Change 1, Paragraphs 11-47 through 11-51 and 11-66
through 11-69.
2.4.4 Pin Identification
The table below shows the pin identifications for the 7-pin connector:
Pin Number Function Pin Number Function
A + Signal input E + Output
B Signal ground F Power ground
C - Signal input G + 28 VDC IN
D Output ground
Phasing: Output pin E is in phase with input pin A and 180 degrees out of phase with input pin C.