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•
WCDMA receiver has to be active before RX VCO's output frequency and output level can be
measured. Procedure is explained in section "Receiver troubleshooting".
•
Measurements can be done with a spectrum analyser and an RF probe. Spectrum analyser centre
frequency should be set according the used RX channel (see section "Frequency mappings"). RBW
and VBW = 1 MHz, Span ≤ 200 kHz.
•
Check the level of the VCO frequency in T7501 outputs. The level should be about -25...-35 dBm. If
the signal level is correct in the input (about -20...-30 dBm) but output level is not as expected
then replace T7501.
4.2.4.9.1 RX VCO G7500 output level high enough?
•
WCDMA receiver has to be active before RX VCO's output frequency and output level can be
measured. Procedure is explained in section "Receiver troubleshooting".
•
Measurements can be done with a spectrum analyser and an RF probe. Spectrum analyser centre
frequency should be set according the used RX channel (see section "Frequency mappings"). RBW
and VBW = 1 MHz, Span ≤ 200 kHz.
•
Connect the RF probe to the T7501 input.
•
Check if the frequency of the RX VCO is as expected. If the VCO signal is not found try to use wider
span setting. The output level of the VCO should be about -20...-30 dBm.
4.2.4.9.1.1 Replace RX VCO G7500
4.2.4.9.2 Replace balun T7501
4.2.4.10 Are capacitors C7530, C7532, C7534 and C7536 in place?
•
Check that components are in place and solder joints are ok
4.2.4.11 VCTCXO frequency and output level correct?
Measurement can be done with an oscilloscope and a probe.
•
•
Connect the probe to C7529 (or C7582)
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The frequency of the VCTCXO should be quite exactly 38.4 MHz and level about 0.5 - 0.9 Vpp.
Example of the correct VCTCXO output signal is presented in figure
1.24V)".
4.2.4.11.1 VXO-voltage ok? (=Vdig).
•
Measurement can be done with an oscilloscope and a probe
•
Connect the probe to C7560 (or C7526, C7513)
VXO-voltage should be about 2.5 V
•
A-106
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Appendix A: RF Troubleshooting
6.5.1 "VCTCXO Output (DC Offset
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