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Figure 128 Oscilloscope screen shots (RF)
Introduction to transmitter tuning
In the transmitter, there are two kinds of tunings that can be done: IQ tuning and power level tuning. In general,
different repairs require different tunings. In order to decide which tuning is necessary after a repair, it is
important to understand the functionality of the repaired circuit. In general, it is recommended that if any TX
component is changed, both these tunings be done. All tunings are done in local mode using Phoenix to control
the phone.
As the RM-25 doesn’t support the EDGE feature, you don’t need to consider operating/tuning the phones in EDGE
mode although Phoenix sometimes has a control selection box to enable EDGE.
Tuning TX/IQ
Context
The tuning must be carried out in all three bands. In addition to Phoenix, a spectrum analyzer (SA) is needed.
Steps
1. Connect the spectrum analyzer (SA) to the RF connector of the module jig. The settings of the SA will depend
on the band to be tuned. The following table summarizes the settings for each of the three bands.
Table 26 Spectrum analyzer settings
GSM900
GSM1800
GSM1900
Center frequency
897.4MHz
1747.8MHz
1880MHz
Frequency span
300kHz
300kHz
300kHz
Resolution Bandwidth
3kHz
3kHz
3kHz
Video Bandwidth
3kHz
3kHz
3kHz
Sweep Time
3 sec
3 sec
3 sec
Trace Type
Clear/Write
Clear/Write
Clear/Write
Detector Type
Max Peak
Max Peak
Max Peak
Reference Level
35dBm
35dBm
35dBm
Marker 1
897.33229 MHz
1747.73229 MHz
1879.93229 MHz
Marker 2
897.4MHz
1747.8MHz
1880MHz
Marker 3
897.46771MHz
1747.86771MHz
1880.06771MHz
2. Open the following two windows in Phoenix:
RM-25
Nokia Customer Care
RF troubleshooting
Page 7–28
Company Confidential
9235618 (Issue 2)
Copyright ©2005 Nokia. All Rights Reserved.