Nokia NPM-2NX Troubleshooting Manual page 43

CCS Technical Documentation
- Center frequency: 133.2 MHz, Span: 200 kHz
- RBW: 3 kHz, reference level: -20 dBm
3) Set phone receiver to continuous mode with the following gain settings using Phoenix
(see picture of controls in step 3).
4) Connect spectrum analyzer probe to the output of GSM IF filter (at the one end of
R804) and record the level.
5) Connect spectrum analyzer probe to the input of GSM IF filter (at the one end of
R803) and record the level.
- If the IF signal levels are according to the picture below and local oscillators are OK
(see step 2 Local oscillator checking) but RX I/Q signal is not correct (see step 3 to check
RX I/Q signal) the problem is probably due too malfunction of either 2nd mixer or AGC
blocks inside Safari. Please note that these levels are measured with active probe.
- If the IF signal level is correct at the filter input but not at the output side the filter
shall be replaced with new one.
- If the IF signal level is not correct at the filter input side and the local oscillators are
OK, inductors L814 and L815 shall be checked, too. If they are OK and there is a signal at
the input of 1st mixer, the problem is probably due to faulty 1st mixer inside Safari.
LNA gain step function can be checked by measuring signal level at L803 and turning ON
and OFF the LNA using Phoenix. The gain should change by 20...25 dB.
Issue 1 07/02 ãNokia Corporation
NPM-2NX
Troubleshooting
Page 43