CCS Technical Documentation
Troubleshooting
RH-13
Issue 1 11/02
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Nokia Corporation
Page 65
RX VHF VCO
The RX VHF VCO signal is used to generate receiver Intermediate frequency. RX VHF VCO
has two fixed frequencies: TDMA 268.08 MHz, GSM 266.4 MHz. Operating frequency is
locked in Phase locked Loop.
RX VHF VCO output signal is fed to SAFARI. Inside the SAFARI signal is divided for Phase
detector and RX parts. Before I/Q-modulator frequency is divided by 2.
Fault finding chart for RX VHF VCO
Note! Measure oscillator frequency over L818 coil. Don’t connect probe to pads!
AMPS/TDMA
-> RX VHF frequency 268.08 MHz
GSM
-> RX VHF frequency 266.4 MHz
Figure 45: Fault finding chart for RX VHF VCO.
1 START HERE
Is oscillator locked
to TDMA 268.08
or GSM 266.4
MHz
OK!
Yes
2
Check resonator
components:
V801, C845, C871,
L818 and DC block C821
3
Check loopifilter
components:
C848, R808, C847,
R807, C846, R820, C870
check also R826
2.No
OK
3.No
OK
4
Change
SAFARI
No
OK