Rx Vhf Vco; Fault Finding Chart For Rx Vhf Vco; Fig 45 Fault Finding Chart For Rx Vhf Vco - Nokia RH-13 Series Troubleshooting Manual

CCS Technical Documentation

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
GSM
3
Check loopifilter
components:
C848, R808, C847,
R807, C846, R820, C870
check also R826
Issue 1 11/02
-> RX VHF frequency 268.08 MHz
-> RX VHF frequency 266.4 MHz
Figure 45: Fault finding chart for RX VHF VCO.
Change
SAFARI
No
1 START HERE
OK
Is oscillator locked
to TDMA 268.08
3.No
or GSM 266.4
MHz
2.No
Check resonator
components:
V801, C845, C871,
L818 and DC block C821
ãNokia Corporation
4
OK
Yes
OK
2
RH-13
Troubleshooting
OK!
Page 65