RM-14
Nokia Customer Care
RF Troubleshooting and Manual Tuning
14
COMPANY CONFIDENTIAL
ISSUE 1 11/04
Copyright © 2004 Nokia. All Rights Reserved.
■
Rx 1800 troubleshooting
Figure 10:RX 1800 troubleshooting
RX 1800 Troubleshooting
GSM1800 ch. 700. Continuous Rx.
Use AGC “gain step” 14
Apply a signal of 1842,86771 MHz (+67.71 kHz offset)
at -90 dBm to the antenna pad J124
Spectrum analyzer: RBW = 500 kHz, VBW = 500 kHz,
center = 1840 MHz and span = 20 MHz
Measure voltage of a) RXI (J512) b) RXQ (J513).
Note: DC level drops after a while.
Change the signal level to -30 dBm
Measure RF level = -30 dBm at Z802 SAW filter input.
Measure Z809 antenna switch control signal voltages
a) VANT_1 = 0V (C811)
b) VANT_2 = 0V (C809)
c) VANT_3 = 0V (C810).
Measure RF level at Helgo input
(C807, not assembled, both terminals).
go to
“Helgo/Synthesizer
troubleshooting”
NOK
OK
OK
(Z800 antenna switch pin11)
OK
NOK
RXI and RXQ = 500 mVpp and 1.35 VDC.