Radio Tuning Procedure
Maintenance 3-13
6. Adjust the softpot value until the squelch just closes.
7. Monitor for squelch chatter; if chatter is present, repeat step 6.
8. When no chatter is detected, select the next softpot and repeat steps 4 - 7 for all test
frequencies shown in the window.
9. Press Program to store the softpot values.
10. If the radio is a 20/25kHz channel spacing model, repeat steps 1 - 10 for 20kHz channel
spacing using the ÔSquelch (20kHz)Õ window.
7.9 Transmit Deviation Limit
The transmit deviation limit softpot sets the maximum deviation of the carrier. Unlike other radios,
the deviation limit for GM950E/GM950i is set using low frequency (PL) rather than the usual 1kHz
tone. The deviation value needs to be set at 7 frequencies across the frequency range. No audio
signals need to be injected, as the radio generates a 82.5Hz tone while the deviation limit alignment
window is open. This tone is used to set the maximum deviation. For 20/25kHz radios, the radio
stores separate tuning data for 20kHz and 25kHz channel spacing. Therefore, both sets of tuning
data should be set independently.
1. From the Service menu, select Tx Alignment.
2. Select Reference Deviation to open the reference deviation tuning window.
3. Set the value to 7 and press Program to store the softpot value.
4. From the Service menu, select Tx Alignment.
5. Select ÔDeviation LimitÕ to open the deviation limit tuning window. This window is used to set the
values for 12.5kHz radios and the 25kHz data for 20/25kHz radios. The window will indicate the
transmit test frequencies to be used.
6. Select the Þrst test frequency shown in the window.
7. Press Toggle PTT to key the radio. The status bar will indicate that the radio is transmitting.
8. Adjust the transmitter deviation to the value shown in table 3-7.
9. Press Toggle PTT to dekey the radio.
10. Repeat steps 6 - 9 for the remaining test frequencies.
11. Press Program to store the softpot values.
12. If the radio is a 20/25kHz channel spacing model, repeat steps 1 - 11 for 20kHz channel
spacing using the ÔDeviation Limit (20kHz)Õ window.
Table 3-7 Transmitter Deviation Limit Alignment Target.
Channel Spacing Deviation
12.5 kHz 375 Hz
20 kHz 600 Hz
25 kHz 750 Hz
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