Vhf Vco - Nokia NSW-5 Series Service Manual

NSW-5
PAMS Technical Documentation
Disassembly and Troubleshooting Instructions

VHF VCO

The VHF VCO signal is used to generate transmitter Intermediate fre-
quencies. The VHF VCO has two fixed frequencies. Operating frequency
is locked in a Phase Locked Loop, which is controlled by baseband.
In AMPS and TDMA800 modes the VHF frequency is 322.38 MHz. In
TDMA1900 mode a higher intermediate frequency is needed, so the op-
erating frequency is increased to 392.46 MHz.
The VHF VCO output signal is fed to the EROTUS LO–pin VV_in. Inside
the EROTUS, the signal is divided for the Phase detector and TX parts.
Before injection to the I/Q–modulator, the frequency is divided by 2 .
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