TRANSMITTER ALIGNMENT METHOD
GXT720/775
1. Frequency Setting
A. Connect a frequency counter or communications service monitor capable of at
least five watt RF.
B. Press the PTT switch.
C. Adjust CT201 trimmer capacitor such that the output frequency is equal to the
channel frequency with a maximum error of +/- 200 Hz. CT201 is located the
right side of VCO Shield can.
2. Output Power Alignment
A. Connect a communications service monitor or a wattmeter and dummy load to
the antenna connector.
B. Press the PTT switch.
C.
Adjust air coil (L6) by spreading or de-spreading, to achieve maximum power at
6V Vcc.
Note: Normally, it is not necessary.
D. Adjust semi-resistor(RV1) by rotate, to achieve 0.5W at 6Vcc
3. Deviation Adjustment
A. Connect an audio generator with 10uF coupling capacitor to the microphone jack.
The audio frequency should be set at 1KHz with a level of 200mV.
B. Connect an FM deviation meter or communications service monitor to the
antenna connector. Set the monitor to read peak deviation.
C. Press the PTT switch.
D. Adjust RV2 for +/- 2.0KHz deviation. RV2 is located the bottom right side of PCB.
