TY96/97 VHF Radio Installation Manual 29 July 2016
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Trig Avionics Limited Page 17
6.2.5 Frequency Step Size
The TY96/TY97 is capable of operating in both an 8.33 kHz and 25 kHz environment. If 8.33 kHz
operation is not required, the 8.33 kHz channels can be disabled to simplify the tuning operation.
Note: 8.33 kHz operation is required in some European airspace.
6.2.6 Auxiliary Input Volume
The auxiliary input is a low-fidelity monophonic input intended for nav radio ident inputs and simple
annunciators. This setting controls the relative volume of the auxiliary audio input.
6.2.7 Auxiliary Input Muting
This allows the auxiliary input to be muted when the radio is receiving or transmitting speech. Turn
this feature ON if the auxiliary input is being used for non-essential services, like an MP3 player. Turn
this feature OFF if the auxiliary input is being used for essential services like annunciators or traffic
alerts.
6.2.8 Sidetone Volume
The audio sidetone is the transmitted audio signal; this setting controls the level of the sidetone in the
headphones.
6.2.9 Receiver Squelch Offset
The receiver has a factory set nominal squelch point of approximately -95 dBm which should be
appropriate for most installations. In some aircraft with noisy electrical environments, such as vintage
or experimental aircraft, the factory setting may lead to nuisance squelch breaking.
The receiver squelch offset allows the installer to moderately increase the squelch set point.
6.2.10 Audio Test Tones
The audio test tones provide a simple way of testing that the installation is correctly wired. The radio
has two stereo headphone outputs, a mono line output, and a cabin speaker output. The audio test tone
generator sends a sequence of tones to each of those outputs in turn.
Use the small right hand knob to scroll through the output choices, and check that each output in turn is
correct. The stereo music and intercom functions will appear in the wrong positions if the wiring is
incorrect.
During the test the volume knob controls the active outputs.
6.2.11 Microphone gain adjustment
The factory set microphone adjustment provides a nominal sensitivity of 100 mV RMS which is
compatible with most conventional aviation headset microphones. Automatic gain control takes care of
variations in speaking voice and variation between different microphones. Microphone adjustment is
therefore only required to correct for alternative installation choices. If the installation uses unusually
high output microphones, or an audio panel with built-in amplification, the radio input can be
overloaded and cause distortion on the transmitted audio. If the microphone output is too low, the
transmitted modulation will be low, and may be unreadable. Each microphone input can be adjusted
separately.
The microphone gain is adjusted in steps of 1 dB. The left end stop on the range corresponds to a
nominal sensitivity of 200 mV; the right end stop corresponds to a nominal sensitivity of 6 mV. The
factory original setting is 6 steps from the left of the range.
6.2.12 LCD Dim Point
The LCD backlight illumination is controlled automatically by the ambient light sensor. Depending on
the amount of light spill in the cockpit, and the brightness of other adjacent avionics displays, it may be
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