Motorola GM1200E Service Manual page 54

GM1200E Tuning Procedure
CAUTION:
1. Set test box (GTF180) meter selection switch to the "AUDIO PA" position and the speaker load
switch to the "MAXAR" position.
2. From the Service menu, select Receiver Alignment.
3. Select RSSI to open the RSSI tuning window. The screen will indicate the receive test
frequency to be used.
The softpot values are displayed for information only and cannot be edited.
4. Set the RF test generator to the receive test frequency, and set the RF level to the value
indicated for RSSI Level 0, modulated with a 1 kHz tone at the normal test deviation shown in
table 4-3. Set test box (GTF180) audio switch to the "SPKR" position. The 1 kHz tone must be
audible to make sure the radio is receiving.
5. Click the Program button to store the softpot value for RSSI Level 0.
6. Repeat steps 4 - 5 for the remaining RSSI levels.
7. Click the Cancel button to close the window.
1.12.2 MPT1327 Transmit Deviation / DTMF Transmit Deviation
The MPT1327 Deviation Softpot is used to tune the FFSK signalling deviation. Tuning is performed
at one frequency. The radio generates an alternating bit pattern for tuning. Values for other
frequencies are calculated by the radio software.
The DTMF Deviation Softpot is used to tune the DTMF signalling deviation. Tuning is performed at
one frequency. The radio generates a DTMF signal for tuning. Values for other frequencies are
calculated by the radio software.
1. From the Service menu, select Transmitter Alignment.
2. Select Signalling Deviation to open the signalling deviation tuning window.
3. Select the MPT value and click the Toggle PTT to key the radio. The status bar will indicate that
the radio is transmitting.
4. Adjust the transmitter deviation to the value shown in table 4-6.
5. Click the Toggle PTT to dekey the radio.
6. Repeat steps 3 - 5 for DTMF deviation.
7. Click the Program button to store the softpot value.
4-8
Inadvertant use of the program buttons may result in radio failure.
Table 4-6 Signalling Deviation
Channel Spacing
12.5 kHz
20 kHz
25 kHz
MPT 1327 Deviation
1.4-1.6 kHz 1.5-1.8 kHz
2.2-2.6 kHz 2.4-2.8 kHz
2.8-3.2 kHz 3.0-3.4 kHz
Radio Tuning Procedure