Northern Airborne Technology NT4xx - Manual (Page 17)

SM04 Rev 4.00 UHF Transceiver Manual
Nov 27, 2003 Page 2-7
ENG-FORM: 805-0106.DOT
CONFIDENTIAL AND PROPRIETARY TO NORTHERN AIRBORNE TECHNOLOGY LTD.
2.3.6.3 Diagnostic Hints
Ensure all antenna mounts are secure, cleanly grounded, and well terminated. Avoid
sharp cable bends in the coax. Never mount any antenna on a composite surface
unless a well grounded and adequately sized ground plane has been provided.
Unusual buzzes, hums or other background audio are symptomatic of multiple grounds,
or noisy external systems such as blowers or pumps sharing wiring with the audio
system connections. Failure to key or correctly modulate a transmitter is often caused
by forgetting to connect all required grounds to the radio or external audio system.
A special caution is that no ground should be taken from the front panel, or similar
location, that shares a ground return with a turn and bank, horizon, or other motor
driven instrument. If this caution is not observed, the sound of the motor may be heard
mixed in with receiver audio.
2.3.6.4 System
Interaction
Fly the aircraft, and check levels and operation of all functions. Display
contrast/dimming may have to be tailored for adequate viewing by the flight crew.
Insure there is not any interaction between any transmit functions and received
NAVAIDS, or other receiver functions. Antenna placement or cable routing may have to
be changed if these problems are encountered. Insure that there is not any interaction
with Tac/Com control head operation and ADF performance. Relocation or re-routing of
the interconnect cabling may be required if interference exists.
2.3.6.5 Final
Inspection
Before leaving the aircraft, ensure that ALL THE MATING CONNECTORS ARE
SECURELY FASTENED TO THE TAC/COM CONTROL HEAD. Also ensure that the
unit is securely fastened to the aircraft from the front panel. Insure that the Tac/Com
Transceivers are securely locked into the tray(s) and all mating connectors are securely
fastened.
If all functions are satisfactory, the aircraft maybe released for service once all required
log entries are made and the required MOT/FAA paperwork is completed.