Specifications

7.2. TRANSMITTER

Connect the unit to a Service Monitor with the power meter set to the 10 W scale (or autorange)

TCXO

Set the channel selector to the mid-range frequency 470 MHz, adjust TCXO1 for a reading of

470MHz ±200Hz (155 MHz VHF models).

TX VCO

TX VCO is pre-tuned at the factory and no more adjustment is required

To identify existence of defect of TX VCO, check the VCO Control voltage.

1. Set the unit to the highest transmit frequency, 490MHz(UHF2), 174MHz(VHF) key the

transmitter and verify the VCO control voltage is under 10.0 Volts. If it’s over 10.0 Volts,

adjust C208 of TX VCO to 10.0 Volts.

2. Set the unit to the lowest transmit frequency 450 MHz(UHF2), 148(VHF) key the

transmitter and verify that the VCO voltage is above 1.8 Volts. Adjust C208 to

1.8 Volts.

※ Note: use TP1 to measure the voltage.

CTCSS, DCS & TX Deviation and Balance Adjustment

1. a. Set the unit to a mid-frequency range and a CTCSS of 67Hz. Activate PTT and adjust

RV402 for desired CTCSS tone deviation.

b. Switch to a channel with the same frequency and CTCSS of 250.3Hz. Activate PTT and

adjust RV1 to desired CTCSS tone deviation, same as above step.

c. Switch between the 67Hz channel and the 250.3Hz channel and adjust RV1 until the

deviation is the same on both channels. It may be necessary to readjust RV402 to get the

desired deviation.

2. Set the unit to a mid-frequency and input the TX data with 400 Hz standard audio level.

3. Increase the signal level to 20 dB from standard level.

4. Monitor the demodulated signal from service monitor. Adjust RV1 to make the monitored

signal to be a balanced square wave.

5. Reduce input signal to the standard level and adjust RV2 for the standard deviation.