Rx 900 Troubleshooting; Fig 9 Rx 900 Troubleshooting - Nokia RM-14 Rf Troubleshooting And Manual Tuning

RM-14
RF Troubleshooting and Manual Tuning
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Rx 900 troubleshooting

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ISSUE 1 11/04
Figure 9:RX 900 troubleshooting
RX 900 Troubleshooting
GSM900 ch. 37. Continuous Rx.
Use AGC "gain step" 14
Apply a signal of 942.46771 MHz (+67.71 kHz offset)
at -90 dBm to the antenna pad J124
Spectrum analyzer: RBW = 500 kHz, VBW = 500 kHz,
center = 942 MHz and span = 20 MHz
Measure voltage of a) RXI (J512) b) RXQ (J513). RXI and
RXQ = 800 mVpp and 1.35 VDC.
Note: DC level drops after a while.
Change the signal level to -30 dBm
Measure RF level = -55 dBm at Z803 SAW filter input.
Measure Z800 antenna switch control signal voltages
a) VANT_1 = 0V (C811)
b) VANT_2 = 0V (C809)
c) VANT_3 = 0V (C810).
Measure RF level = -55 dBm
at Helgo input (C808, both terminals).
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