P.A.M.S.
Technical Documentation
NME–2A
Troubleshooting Instructions
Page 16
Original 08/97
2.1. Check the VCXO:
After AFC is done, the tuning voltage will stay high.
In other modes the tuning voltage will be in mid.
– Measure at J902: > 3 V
PP
– High tuning: freq = 26 MHz +400 Hz ±100 Hz
– Low tuning: freq = 26 MHz –400 Hz ±100 Hz
– Mid tuning: freq = 26 MHz ±50 Hz
2.2. Check burst mode:
Select via PCLocals RF control, Active unit RX, Operation mode burst,
Continuous mode channel 60, AGC 93. Input –57 dBm 947.06771 MHz.
AGC is in that mode internally controlled.
Measure with scope ac coupled on RXI and RXQ, the output to RFI. Trig
the scope on RXPWR or 8.5RX TX SW or AGC0.
– Signal should be about 30 mV
PP
, and vary as the AGC operates.
– If not check the signal path and the LO signals as above.
3. Noise and sensitivity:
Checks the overall RX performance, except real demodulation.
Use F2 to measure clipping level and difference between I–Q.
Disconnect or switch off the RF signal from the generator.
Use F3 to measure SNR and Sensitivity.
– Clipping + SNR >50
– SNR > 20
– Sensitivity < –103 dBm
– I–Q < 1 dB
– If not repeat from 1 again.
4. Check camp on to HP8922G/H:
Set HP8922G/H up with neighbors for its own BCCH and some empty and
some used channels. In cph use 3, 5, 20 (=own BCCH), 59 and 90.
Use PCLocals F8 to monitor the radio.
– RXlevel within ±2 dB from the BCCH level.
– RXlevel for empty neighbors less than 3.
– Decoding of the information in the used neighbors
– If not OK, the malfunction may be in the RFI and the circuits that con-
trol the RFI.
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