User's Manual
Transmitter Alignment
Automatic Power Adjustment
Transmit periods longer than 3 minutes are to be avoided.
1. Switch to data radio to TX.
2. Adjust RV1 to give the appropriate transmit power.
3. Record the transmit power set.
4. Switch the data radio to transmitter OFF.
Frequency accuracy
1. Whilst transmitting, measure the transmit frequency using the RF frequency counter.
2. On the TCXO PCB, adjust trimmer capacitor VC700 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 60deviation.
3. Set the AF signal to 1 kHz.
4. Set the RF level to 1 mV pd (- 47.0 dBm)
5. Adjust T2 for a maximum audio output (viewed on oscilloscope).
6. Adjust L16 and L17 for lowest distortion; this is normally less than 3.
7. Check for an RF voltage signal level of 0.35uV pd (- 116dBm) and a SINAD meter Reading
greater than 12 dB.
Repeat steps 7 to 9 as necessary.
Squelch ⁄ Carrier Detect Adjustment
1. Set the RF signal generator to the receiver frequency with 60deviation. Set the AF
a. Signal to 1 kHz
2. Set RF input level to give -115 dBm.
3. Adjust RV2 until CDS J501 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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