TFE-4/RV-1
Company Confidential
TF4 Technical Information
Nokia Customer Care
Page 8b-60
Copyright
©
2005
Nokia Corporation.
Issue 2.0 Mar/2005
Company Confidential
TF-4 Synthesizer
There is only one PLL synthesizer generating frequencies for both Rx and TX and for all
two bands (EGSM900 and GSM1800). VCO frequency is divided by 2 or by 4 in Mjoelner
depending on which band is active.
General instructions for Synthesizer troubleshooting
Step 1: Setting up Phone and Phoenix
• Start Phoenix Service Software
• Open the FBUS connection
• Select File /Scan Product (Ctrl-R)
• Wait until phone information shows in the lower right corner of the screen.
• Set operating mode to local mode
• Activate RF-Controls
• Select Maintenance/ Testing/ RF Controls
Wait until the RF Controls window pops up
• Select:
Band
GSM 900 or GMS1800
Active unit
RX
Operation mode
Continuous
RX/TX Channel
37 or 700
The setup should now look like this:
Step 2:
Doing the Measurement
Since VCO chamber is completely shielded, it is not easy to measure frequency of
3769.6MHz at the output of the VCO (G701) using a resistive probe and a spectrum ana-
lyzer. It is possible to measure tuning voltage at charge pump output (C710) easily. For
f
VCO
= 3769.6MHz the tuning voltage should be 2.3V
DC
.. 2.8V
DC
(Tuning sensitivity of
VCO is 240MHz/V typ.).
If this is not the case, then go to section 1.4 of this document for troubleshooting.