Rx 1900 Troubleshooting; Fig 11 Rx 1900 Troubleshooting - Nokia RM-14 Rf Troubleshooting And Manual Tuning

RM-14
RF Troubleshooting and Manual Tuning
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Rx 1900 troubleshooting

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ISSUE 1 11/04
Figure 11:RX 1900 troubleshooting
RX 1900 Troubleshooting
GSM1900 ch. 661. Continuous Rx.
Use AGC "gain step" 12.
Apply a signal of 1960,06771 MHz (+67.71 kHz offset)
at -90 dBm to the antenna pad J124.
Spectrum analyzer: RBW = 500 kHz, VBW = 500 kHz,
f = 1960 MHz and span = 20 MHz
Measure voltage of a) RXI (J512) b) RXQ (J513). RXI and
RXQ = 700 mVpp and 1.35 VDC.
Change the signal level to -50 dBm and set "gain step" = 6
Measure RF level at Z801 SAW filter input.
(Z800 antenna switch pin1)
Measure antenna switch control signal voltages
a) VANT_1 = 0V (C811)
b) VANT_2 = 2.7V (C809)
c) VANT_3 = 2.7V (C810).
Measure RF level at V800 LNA input (C801).
Measure RF level at V800 LNA output (C804)
Measure a) V800 LNA supply voltage LNA_P = 2.8 V (V800 pin 4)
and b) LNA control voltage LNAB_P = 2,8 V (R801)
Measure RF level at N500 Helgo input (L807).
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