User Guide

PAMS Technical Documentation Troubleshooting Instructions
NPW-1
Issue 1 10/01 ãNokia Corporation Page 37
Figure 18: Fault tree: RX VHF VCO
TX VHF VCO
The TX VHF VCO signal is used to generate transmitter Intermediate frequency. TX VHF
VCO has two fixed frequencies 361.08 MHz for lower band and 363.6 MHz for upper
band. Operating frequency is locked in Phase locked Loop and frequency is divided by
two before modulator.
Fault finding chart for TX VHF VCO
AMPS, CH383 -> TX VHF frequency 361.08 MHz
TDMA1900, CH1000 -> TX VHF frequency 363.6 MHz
1
START HERE
Is oscillator locked
to 271.08 MHz
OK!
Yes
2
Check resonator
components:
V725, C724, C725,
L730 and DC block C726
3
Check loopifilter
components:
C720, R721, C721, R722,
C722, R733, C733
check also R724
2.No
OK
3.No
OK
4
Change
SAFARI
No
OK