NGT—Checks and adjustments
166 NGT Transceiver System Technical Service Manual
Checking the voltage-controlled oscillator
VCO1 is located on the RF/IF PCB in the RF unit. There is no adjustment available for
VCO, but it can be checked to ensure it is operating correctly.
To check the operation of VCO:
1 Ensure a screening can is over VCO and RxMIX1.
1 Select test channel 1.
1 Connect a DC voltmeter to TP402 and check that the voltage is between 2 V and
4V.
The frequency at VCO test point should be approximately 45.25 MHz.
1 Select test channel 2.
1 Check that the voltage at TP402 is between 9 V and 11.5 V.
The frequency at VCO test point should be approximately 60 MHz.
1 Select test channel 3.
1 Check that the voltage at TP402 is between 19 V and 25 V.
The frequency at VCO test point should be approximately 75 MHz.
ALTERNATIVE TEXT
Drawing 08-05261 (sheet 2) or 08-05889 (sheet 2)
NOTE If the PCB issue status is -06 or earlier, see drawing 08-05889 (sheet 2).
NOTE
The transceiver must be in Service mode to perform this check (see
page 154, Accessing Service mode).
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