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NSD-6
Disassembly/Troubleshooting Instructions
AMPS Tuning AFC
Description of Test
This test tunes the VCTCXO to exactly 19.2 MHz using a DC voltage (TP100) controlled by
the AFC PDM. The resulting PDM is stored to eeprom.
The unmodulated AMPS transmitter is set on Channel. 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 carrier frequency is within ±250Hz of 841.5MHz (i.e. Channel 550).
The AFC must be tuned if the VCTCXO is replaced.
On SSP phones where there is no AMPS, the PCS transmitter is used; however, the CDMA
IQ modulation is switched off and the AFC is tuned on the CW carrier.
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
The result of this tuning is the AFC PDM stored to eeprom which puts the VCTCXO at the
correct frequency.
Manual Verification
Use WinTesla as follows:
Page 24
Nokia Mobile Phones Ltd.
PAMS Technical Documentation
Issue 1 04/01
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Troubleshooting
