Synthesizer Troubleshooting; Introduction - Nokia RH-64 Service Manual

RH-64
Nokia Customer Care RF troubleshooting
Figure 139 TXC signals at PCL15

Synthesizer troubleshooting

Introduction

There is only one PLL synthesizer generating Local Oscillator frequencies for both RX and TX in both bands (PCN
and EGSM). The VCO frequency is divided by 2 for PCN operation or by 4 for EGSM operation inside the RF IC.
The 26MHz oscillator is located near the RF IC (N7600). The coarse frequency for this oscillator is set by an external
crystal (B7600). The reference oscillator is used as a reference frequency for the PLL synthesizer and as the
system clock for the Baseband. The 26MHz signal is divided by 2 to achieve 13MHz inside the UPP IC (D2800).
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