Service Manual

Transmitter Alignment
Automatic Power Adjustment
Transmit periods longer than 3 minutes are to be avoided.
1. Switch to data radio to TX.
2. make the transmit power between 2 to 3W.
3. Switch the data radio to transmitter OFF.
Frequency accuracy
1. Whilst transmitting, measure the transmit frequency using the RF frequency counter.
2. Adjust VR1 so that frequency is as close as possible to the exact required transmit
frequency. Ideally it should be within 100 Hz at room temperature.
Receiver Alignment
Important note：Before setting up the receiver it is important to check the frequency
accuracy alignment is correct as described in the transmitter alignment section.
RF tuning
1. Connect an RF signal generator and SINAD voltmeter.
2. Set the RF signal generator to the receive channel frequency and set to 60﹪deviation.
3. Set the AF signal to 1 kHz.
4. Set the RF level to 1 mV pd (- 47.0 dBm )
5. Adjust T2 for maximum AF output about 250mVto 350mV and lowest distortion,
the distortion normally less than 5﹪.
6. Check for an RF voltage signal level of 0.35uV pd (- 116dBm)and a SINAD meter
Reading greater than 12 dB.
Squelch/Carrier Detect Adjustment
1. Set the RF signal generator to the receiver frequency with 60﹪deviation. Set the AF
Signal to 1 kHz
2. Set RF input level to give -112 dBm.
3. Adjust VR101 until CDS J1 pin 6 changes state from “HIGH” to “LOW”.
4. Reduce RF input level to –120dBm and check that CDS line goes HIGH . Switch
off the RF generator and disconnect the test equipment.
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