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For Motor Glider and Ultralights install the following intercom switch wiring. Wire the center
conductor to PIN 5 and the shield to ground. The switch is the same as for the backlight switch
described previously or when the switch is not used, you can use voice operation (VOX
function).
Memory toggle center conductor to PIN 13 and the shield to ground. The memory toggle switch
is momentary type with the center conductor to common and the shield to normally open.
You may have noted that nearly all switch connections are to ground, this was done to simplify
wiring and avoid any possible shorts to positive voltages.
5.7 Antenna Installation
The following section refers to proper antenna installation.
NOTE: In certified aircraft approved antennas must be used.
5.8 Tuning
Before any tuning can be attempted you must have a VSWR meter which can measure the
antenna’s reflected power. The lower the SWR reading the higher the output and the
radiated signal. High SWR degrades performance and can cause damage.
An SWR of <1.5:1 is desirable.
5.9 On air testing
Before transmitting check all connections and switch on. Operate controls as per section 6.
A simple on air test for audio quality on transmit and receive should be done.
Have someone monitor your signal on another radio. Transmit and speak into the
microphone at normal level. If the received signal is quiet then the mike gain control will
need to be adjusted. If the signal is loud and distorted then it will need to be turned down.
These adjustments should be done using a comm. test set.
Have another radio transmit a test call and monitor the audio quality. With the volume
control turned to the 3/4 position the audio should be loud and not distorted. Distortion
could be caused by the choice of speaker. A 4 watt speaker is recommended as a minimum
power rating. Set the squelch and have the station transmit, the squelch should break
crisply and without delay.
Note;
Do not transmit on 121.500MHz, as this is the international distress frequency.
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