High power—Fault finding and adjustments
242 NGT Transceiver System Technical Service Manual
Adjusting the power supply operating area
To adjust the power supply operating area:
1 Ensure there is no audio drive to the NGT.
1 Use a cliplead to connect +5 V (X4) to the 10-pin header pin 4 (P1/4).
1 Hold down PTT.
1 Set the Voltage Adjust preset potentiometer R7 to give 50.0 V DC at X2.
1 Remove the cliplead, and check that the voltage at X2 drops to approximately
33 V DC.
1 Using an active load connected from X2 to ground, set the load current drain to
9.5 A.
1 Adjust the Current Limit preset potentiometer R12 to give 43.6 V DC at X2.
1 Move the active load to output terminal X3, and set the Current Limit preset
potentiometer R112 to give 43.6 V DC at X3.
1 Release PTT.
1 Repeat the above tests for the other Power Supply PCB (3062 only).
Adjusting the input attenuator
If it is found during testing that the amplifier output is controlled by the NGT rather than
the power amplifier, this indicates that the gain of the power amplifier is low. This can be
increased by removing the link X1 from the Splitter 2-way (500 W) PCB or Splitter
4-way (1 kW) PCB.
Drawing 08-05978 (sheet 1), 08-05978 (sheet 2) and 08-05978 (sheet 3)
NOTE
The transceiver does not have to be in Service mode to perform this
adjustment.
NOTE The header can be removed for this adjustment.
Drawing 08-05997 or 08-05999
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