Nat SM05, Installation And Operation Manual

Page: 16 / 56

VHF Transceiver Manual SM05 Rev 4.00
Nov 26, 2003 Page 1-6
ENG-FORM: 800-0107.DOT
CONFIDENTIAL AND PROPRIETARY TO NORTHERN AIRBORNE TECHNOLOGY LTD.
2.3.6 Post-Installation Checks
2.3.6.1 Wiring
Checks
a)
With the Tac/Com control head disconnected from all of its mating connectors,
make the following measurements on P100 SYSTEM connector (25 pin female),
if used:
i) Check pin 1 and 2 for +28 VDC (or 14 VDC) relative to ground.
ii) Check pins 13, 14 and 15 for continuity to ground (below 0.5 ohms).
iii) Check pin 3 (28 VDC), pin 4 (14 VDC) or pin 5 (5 VDC) for proper lamp
dimmer voltage. Check 16, 17 or 18 for continuity to ground as above
(lamp return).
DO NOT ATTACH THE TAC/COM CONTROL HEAD until these conditions are met.
b)
With the Tac/Com Transceiver disconnected from all of its mating connectors,
make the following measurements on the airframe (female cable end) connector:
i) Check pin 1 and 2 for +28VDC relative to ground.
ii) Check pins 14 and 15 for continuity to ground (below 0.1 ohms).
iii) Check pin 6 for PTT action (closure to ground when keyed), and pin 5 for
mic connection. Note that these are commonly reversed by accident, and
will result in transceiver keying, but no modulation.
iv) Check pins 11 and 24 for continuity to the ship's audio system as required
for RX audio.
d)
ENSURE that neither pin 12 or 25 is connected to ground, or immediate failure of
the radio will result. This (optional) speaker line is a bridge output, and must be
floating above the airframe ground.
e)
Ring out the channeling lines to the control head connector, and check for shorts
on all shielded cables. Note that a quick check of these lines will save many
wasted hours later, and possible control head and R/T damage.
f)
Check the RF connector for continuity to the antenna, and open circuit to ground
from the center conductor.