c) Signal generator Adjustment for RX sensitivity test
1) Adjust SSG to channel frequency.
2) Adjust modulation frequency, 1kHz to modulation degree, 1.5 kHz.
3) After adjusting the frequency of SSG to channel frequency, set RF level
to -47dBm.
d) Check and adjust Squelch sensitivity
1) Set the standard channel.
2) In squelch mode, SQ volume RV1 must be turned counterclockwise to open the squelch.
3) After adjusting SSG to channel frequency, the RF level of SSG is set
so that a SINAD of 8
∼
6dB is obtained. Turn potentiometer carefully so that
Squelch just opens at that point.
4.5 RECEIVER TEST
a) Rx sensitivity test
SSG should be adjusted to 12dB of SINAD's point needle
Observe waveform of oscilloscope at signal generator signal modulated with 1kHz
audio and 1.5 kHz frequency deviation. The 12 dB Sinad point should be reached with an
RF level of –110 to -107Bm. This is a good sensitivity.
b) Audio Distortion Test
1) SSG should be adjusted like way of point a) and RF level set to -47dBm.
2) Adjust to 0.7Vrms( at 8 Ohms load) observing audio wave form.
3) Read the needle of distortion meter (it should be less than 5% distortion).
c) Squelch Test
After RF level of SSG should be set to the lowest level, RF level should
be gradually increased until speaker makes audio sound. At this point,
check RF level(Check if the SINAD is 8
∼
6dB). Check that squelch will close when Level is
reduced to minimum. If not, readjust RV 1 and check again.
4.6 Symtoms, Check point & Correction
a) Diagnosis method
1) Check each switch to work well.
2) Check voltage of battery.
3) Problem whether problem comes from transmitter or receiver?
b) Troubleshooting
a)Transmitter
①
Power key is on condition but does not work.
