Tx Vhf Vco; Fault Finding Chart For Tx Vhf Vco - Nokia NPM-2NX Troubleshooting Manual

NPM-2NX
Troubleshooting
GSM-> BB PLL frequency 78 MHz
3
Check loopfilter
components:
C878, R834, C881, R835,
C882

TX VHF VCO

The TX VHF VCO signal is used to generate transmitter Intermediate frequency. TX VHF
VCO has three fixed frequencies 358.08 MHz for lower band and TDMA 428.16 MHz and
GSM 426.4 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 358.08 MHz
TDMA1900, CH1000-> TX VHF frequency 428.16 MHz
Page 58
4
Change
SAFARI
OK
No
1 START HERE
OK
Is oscillator locked
to TDMA 77.76 or
3.No
GSM 78 MHz
2.No
OK
Check resonator
components:
V805, C871,
L829 and C893
ãNokia Corporation
CCS Technical Documentation
Yes
2
OK!
Issue 1 07/02