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CCS Technical Documentation
GSM1900, CH661
4
Check components:
C853, C852, C851,
R810, R809, R821 and
C841, C873, L828
3
Check resonator
components:
V802, C850, L820,
C874, C865
UHF SYNTHESIZER
The UHF synthesizer consists of a external 2GHz UHF VCO, loop filter and integrated PLL
in Safari RF-IC. Safari GTE IC contains stages like counters, prescaler, divider by two,
phase and frequency comparator and a charge pump circuit which allows two opera-
tional modes analog and digital. The UHF VCO Oscillation frequency is from 2006.16
MHz to 2124 MHz
In upper band (TDMA1900 &GSM1900) 2 GHz synthesizer frequency is fed straight to
mixers. In lower band case (AMPS & TDMA800) 2 GHZ UHF VCO frequency signal is first
divided by 2 inside SAFARI and then that divided signal is fed to mixers. The output fre-
quency of the VCO depends on the DC-control voltage which is controlled by PLL-circuit
inside SAFARI.
Issue 1 07/02
-> TX VHF frequency 426.4 MHz
5
Change
cascade amplifier
N811
OK
5.No OK
4.No
1
START HERE
Is oscillator locked
OK
to 358.08, 426.4
3.No
or 428.16 MHz
2.No
OK
2
Check operating
voltage:
4.75 V
at R833
ãNokia Corporation
NPM-2NX
Troubleshooting
6
6.No
Change
OK
SAFARI
Yes
OK!
No
Check:
L819, R833
OK
Page 59
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Table of Contents
Troubleshooting
