Checking The Voltage-Controlled Oscillator - Codan NGT 2010 RF Technical & Service Manual

NGT—Checks and adjustments

Checking the voltage-controlled oscillator

Drawing
ALTERNATIVE TEXT
NOTE
NOTE
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
1
1
1
1
1
1
166
08-05261 (sheet 2)
If the PCB issue status is -06 or earlier, see drawing
The transceiver must be in Service mode to perform this check (see
page 154, Accessing Service
Ensure a screening can is over VCO and RxMIX1.
Select test channel 1.
Connect a DC voltmeter to TP402 and check that the voltage is between 2 V and
4 V.
The frequency at VCO test point should be approximately 45.25 MHz.
Select test channel 2.
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.
Select test channel 3.
Check that the voltage at TP402 is between 19 V and 25 V.
The frequency at VCO test point should be approximately 75 MHz.
or 08-05889 (sheet 2)
mode).
NGT Transceiver System Technical Service Manual
08-05889 (sheet 2).