Introduction To Transmitter Tuning; Tuning Tx/Iq - Nokia RM-51 Service Manual

RM-51
RF troubleshooting

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 this mobile 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.
Center frequency
Frequency span
Resolution Bandwidth
Video Bandwidth
Sweep Time
Trace Type
Detector Type
Reference Level
Marker 1
Marker 2
Marker 3
2. Open the following two windows in Phoenix:
9238460 (Issue 1)
Figure 141 Oscilloscope screen shots (RF)
Table 8 Spectrum analyzer settings
GSM900
897.4MHz
300kHz
3kHz
3kHz
3 sec
Clear/Write
Max Peak
35dBm
897.33229 MHz
897.4MHz
897.46771MHz
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GSM1800
1747.8MHz
300kHz
3kHz
3kHz
3 sec
Clear/Write
Max Peak
35dBm
1747.73229 MHz
1747.8MHz
1747.86771MHz
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GSM1900
1880MHz
300kHz
3kHz
3kHz
3 sec
Clear/Write
Max Peak
35dBm
1879.93229 MHz
1880MHz
1880.06771MHz
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