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7.11
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 3-6.
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.
7.12
Signalling Alignments
7.12.1
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.
INADVERTANT USE OF THE PROGRAM BUTTONS MAY RESULT IN RADIO FAILURE.
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.
Maintenance
Table 3-7 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
Radio Tuning Procedure
3-13
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