User's Manual

An FM demodulator should be connected to the RF output of the module through a suitable
power attenuator or coupler. The demodulator filters should be set for no de-emphasis, as low a
highpass cutoff as possible (<50 Hz, preferably down to DC), and a lowpass cutoff of
approximately 15 kHz. The demodulator output should be connected to an oscilloscope so that it
can be observed.
An audio oscillator should be connected to the AUX IN input. The output waveform should be
sine, the level at zero, and at a frequency of 500 Hz. Confirm that the Aux In Gain value is at least
10.
On the channel drop-down menu, select lower band edge. Activate the PTT, and while observing
the demodulated waveform on the oscilloscope, begin increasing the audio oscillator’s output
level or the Aux In setting. The waveform should begin as a sinewave and at some point show
clipping. The clipped portion may not necessarily be flat. The audio oscillator level should be set
so that a substantial portion of the waveform is clipped, at least 50 %. Adjust the balance value
so that the clipped portion is flat i.e. horizontal rather than tilted. Although the programmer can
change values while transmitting, it is better to unkey between value entries. After the balance is
set, the deviation should be set to a value of 1.2 kHz for a very narrow channel, 2.3 kHz for a 12.5
kHz channel or 4.6 kHz for a 25/30 kHz channel. Select the upper band edge on the channel
menu and repeat. As a result of this procedure, the per channel balance and deviation values
may have changed.