User Guide

PAMS Technical Documentation 10. Troubleshooting
NSD-5
Issue 1 05/02 Nokia Corporation Page 27
ulation is switched off. The output carrier is monitored with a spectrum analyzer. Click
on WinTesla Help for equipment set-up. The AFC PDM is tuned until the RF CW carrier
frequency is within +/-250Hz of 2073.1MHz (i.e., Channel 300).
Note: The Spectrum Analyzer must be connected to a high-stability, 10MHz reference at
the rear of the instrument. If this is not done, then the tuning will not be accurate.
Definition of Result
As a result of this tuning, the AFC PDM is stored to EEPROM, which puts the VCTCXO at
the correct frequency.
Manual Verification
Use WinTesla as follows:
1. Select Tuning from the WinTesla main menu and choose 1900 PCS and AFC... from
the drop-down menus.
2. The “Tuning AFC” dialog box is displayed. Use this box to adjust the Present AFC val-
ues, using the U
p and Dn buttons or the PgUp or PgDn buttons.
3. Select either the Save & Exit button or the No Save & Exit button when through.
Synthesizer Troubleshooting
The VCTCXO reference designator is G501. VR1 supplies 2.7V to the VCTCXO through
R501, decoupled with C561. The VCTCXO is controlled by a DC level from the AFC PDM in
MAD, connected to Pin1. The PDM is filtered by R141 and C141 in the baseband section
and by R504 and C507 in the RF section. Typically, a correctly tuned VCTCXO should have
approximately 1.5 volts on Pin 1.