Receiver - Tait TB8100 Service Manual

3.8

Receiver

Task 1 —
Check Synthesizer
Task 2 —
Check Sensitivity
TB8100 Service Manual
© Tait Electronics Limited September 2006
These checks will verify whether:
the receiver synthesizer is locked
the sensitivity is correct.
1. Set up the test equipment as shown in
2. Run the Service Kit and connect to the reciter. Put the reciter in
Standby mode. Select Diagnose > Reciter > Synthesizers.
3. Check that the receiver synthesizer is locked. If it is, go to
it is not, go to Step
4. Click Start Test in the receiver row.
5. Check that the synthesizer lock range matches the frequencies
displayed in the Receiver setting box in the Monitor > Module
Details > Reciter form. If the two frequency ranges match, go to
Task 2. If they do not match, adjust the receiver lock band using the
Calibration Kit and repeat this task.
1. Select Diagnose > Reciter > Receiver.
2. Inject an RF test signal (1kHz audio, 60% modulation) of the
required frequency at –117dBm (0.32µV) into the antenna input.
3. In the Receiver values area, check that the Current RSSI value
matches the level of the test signal, and the Current SINAD value is
greater than 12dB. If the levels are correct, go to
not, go to Step
Note
The sensitivity for de-emphasised response will be different from
flat response (refer to
4. Retune the receiver front end and recalibrate the RSSI using the
Calibration Kit. Repeat the test. If the levels are correct, go to
Step 5. If they are not, the digital board is faulty. Return the
complete reciter to your nearest CSO for repair or replacement.
5. Check the SINAD sensitivity and RSSI at –60dBm (223.6µV),
–100dBm (2.2µV), and –117dBm (0.32µV).
The RSSI reading in the Service Kit should be within ±1dB of the
signal level of the test set. If it is not, recalibrate the RSSI using the
Calibration Kit and repeat the test.
The SINAD sensitivity should be at least 12dB at –117dBm. If it is
not, and the digital IF is not faulty
faulty. Return the complete reciter to your nearest CSO for repair or
replacement.
If the RSSI and sensitivity are correct, go to
4.
4.
Table 3.2 on page
(Section
Figure 3.2 on page 73.
Task
Step 5. If they are
96).
3.7), the RF board is
"Exciter" on page
Reciter Fault Finding
2. If
86.
85