Frequency Generating Section Detailed Circuit Description - Motorola MTH500 Service Manual

Frequency Generating Section Detailed Circuit Description

Dual Synthesizer
Data
Reference
Oscillator - TCXO
68P02963C70-O
See Figure 12.
This section describes the generating circuits that supply all the required frequen-
cies for the required transmitter and receiver functions. These circuits are de-
scribed as follows:
• REF. Oscillator - TCXO.
• Main VCO and Main Synthesizer.
• Second IF VCO and Dual Synthesizer RF section.
• Offset VCO and Dual Synthesizer IF section.
(U808)
IF Section
DOI F
50kHz
OSC_IN
FINIF
Divider
RF Section
DORF
OSC_IN
100kH z
FINRF
LOIN
Main VCO
WPI C
CPGITR
XTALBASE
PRSCI N
Figure 12 Frequency Generating Section - Block Diagram
Of fset VCO
LPF
Osc.
Second LO
219.3MHz
LPF
Osc.
Main Synthesizer
Buf fer
LPF
Osc.
Theory of Operation
113.65 MHz to Offset Mixer
493.65-513.65 MHz to RX Mixe
493.65-513.65 MHz to TX Mixer
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