Tac/Com Control Head Manual

SM06 Rev. 4.10

2.5Troubleshooting2.5.1Weak Receive/Transmit, Intermittent Operation, Erratic Squelch

Ensure all antenna mounts are secure, cleanly grounded, and well terminated. Avoid sharp coax cable bends or crushed coax from tie wraps. Never mount any antenna on a composite surface unless a well-grounded and adequately sized (equal in radius to the height of the antenna) ground plane has been provided. Keep antennas widely separated, especially between VHF radios, and VHF and UHF radios. Bad antenna matches and close proximity will result in large amounts of spurious radiation, which may affect VHF-FM to VHF-AM operation and may result in harmonic interference between VHF and UHF radios.

2.5.2Strange Noises, No Receive Audio, Transmit Keying problems

Buzzes, hums or other background audio noises are symptomatic of multiple grounds or noisy external systems such as inverters, blowers or pumps sharing wiring with the audio system connections. Failure to key or correctly modulate a transmitter, or no receive audio is often caused by not connecting all required grounds or wires to the radio or external audio system. Check to make sure that the MIC AUDIO and PTT lines are not reversed (keys, but no TX audio). Be sure both audio output wires are connected from the transceivers (no or very faint RX audio).

A special caution is that no audio ground should be taken from the front instrument panel or similar location that shares a ground return with a turn and bank or horizon or other motor driven instrument. If this caution is not observed, the sound of the t&b motor may be heard mixed in with receiver audio.

2.5.3Some Frequencies Can't be Edited

Some frequencies are not really agile entries (such as crystal guard frequencies), and as such should not be edited during normal operation. All such entries must be set via the MASTER EDIT mode (see Section 3.11).

When in the SIMPLEX mode (RX and TX frequency lines display an 's'), you cannot edit the TRANSMIT portion of the radio channel assignments because there is actually a valid TRANSMIT frequency stored. It is temporarily hidden because of the SIMPLEX function. To edit these frequencies, simply return the control head to DUPLEX operation via the STATUS EDIT function or front panel switch, as appropriate.

2.5.4Display Brightness is Too Low, Can't Increase to Full Brightness

The intensity of the display is set by two functions, the level set from the display screen (advance the cursor past the last radio, then set the brightness up or down with the SELECT switch) AND the status of the panel dimmer line. If the dimmer is active, then the display automatically dims to HALF BRIGHTNESS of the previous setting. In some

Page 2-6

Jan 4, 2006

ENG-FORM: 805-0108.DOT

 

CONFIDENTIAL AND PROPRIETARY TO NORTHERN AIRBORNE TECHNOLOGY LTD.