Tx Vhf Vco; Fault Finding Chart For Tx Vhf Vco; Fig 48 Fault Finding Chart For Tx Vhf Vco - Nokia RH-13 Series Troubleshooting Manual

RH-13
Troubleshooting

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
TDMA1900, CH1000
GSM850, CH189
GSM1900, CH661
4
Check components:
C853, C852, C851,
R810, R809, R821 and
C841, C873, L828
3
Check resonator
components:
V802, C850, L820,
C874, C865
Page 68
-> TX VHF frequency 358.08 MHz
-> TX VHF frequency 428.16 MHz
-> TX VHF frequency 356.4 MHz
-> TX VHF frequency 426.4 MHz
Figure 48: Fault finding chart for TX VHF VCO.
Change
cascade amplifier
OK
5.No OK
4.No
1 START HERE
Is oscillator locked
to 356.4, 358.08,
OK
426.4
3.No or 428.16 MHz
2.No
Check operating
voltage:
4.75 V
at R833
ãNokia Corporation
CCS Technical Documentation
5
N811
6.No
OK
Yes
OK
2
No
OK
6
Change
SAFARI
OK!
Check:
L819, R833
Issue 1 11/02