Motorola GM1200E Service Manual download pdf (Page 53)

GM1200E Tuning Procedure

Radio Tuning Procedure 4-7

7. Change the input tone to 3 kHz, 200 mVrms.

8. Adjust the deviation to within ±2% of the value recorded in step 6.

9. Check the deviation at 80 Hz again and repeat step 7-8, if it has changed since step 6.

10. Click the Toggle PTT to dekey the radio.

11. Repeat steps 3 - 10 for the remaining test frequencies.

12. Click the Program button to store the softpot values.

Note: The step size change for step 8 is approximately 2.5% softpot value.

1.11 Transmit Deviation Limit

The transmit deviation limit softpot sets the maximum deviation of the carrier. The deviation value

needs to be set at 7 frequencies across the frequency range.

1. From the Service menu, select Transmitter Alignment.

2. Select Reference Attenuation to open the reference attenuation tuning window.

3. Set the maximum value and press Program to store the softpot value.

4. From the Service menu, select Transmitter Alignment.

5. Select VCO Attenuation to open the deviation limit tuning window. The window will indicate the

transmit test frequencies to be used.

6. Set the Test Box (GTF180) meter selector switch to the “GEN” position, and inject a 1 kHz tone

at 800 mVrms into the "Audio In" port. Connect an AC meter to the meter port to ensure the

proper input signal level.

7. Select the ﬁrst test frequency shown in the window.

8. Click the Toggle PTT to key the radio. The status bar will indicate that the radio is transmitting.

9. Adjust the transmitter deviation to the value shown in table 4-5.

10. Click the Toggle PTT to dekey the radio.

11. Repeat steps 8 - 10 for the remaining test frequencies.

12. Click the Program button to store the softpot values.

1.12 Signalling Alignments

1.12.1 MPT RSSI Threshold Level

The Program buttons must only be activated when the required signal is input to the radio and the

radio is receiving. If the DPS detects that the input signal is not within the expected range for the

RSSI level in question then a message will be displayed to warn that the radio may not be set up

correctly for the alignment operation.

Table 4-5 Transmitter Deviation

Channel Spacing Deviation

12.5 kHz 2.2-2.3 kHz

20 kHz 3.4-3.6 kHz

25 kHz 4.3-4.6 kHz

1 2 ... 48 49 50 51 52 53 54 55 56 57 58 ... 61 62

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Motorola GM1200E Service Manual Page 53