Chapter 1
THEORY OF OPERATION
1.0 Introduction
This Chapter provides a detailed theory of operation for the VHF circuits in the radio. Schematic
diagrams and board layout diagrams are included in Chapter 4 in this Section of the manual.
2.0 Transmitter
2.1 General
(Refer to Figure 2-1)
The VHF transmitter contains five basic circuits:
1. Power Amplifier
2. Antenna Switch
3. Harmonic Filter
4. Antenna Matching Network
5. Power Control Integrated Circuit (PCIC).
2.1.1 Power Amplifier
The power amplifier consists of two devices:
1. 9Z67 LDMOS driver IC (U3501) and
2. *PRF1507 LDMOS PA (Q3501).
Figure 1-1 Transmitter Block Diagram
PCIC
Antenna
PA
Driver
Vcontrol
Vcontrol
From VCO
Jack
PA - Final
Stage
Antenna Switch/
Harmonic Filter/
Matching Network
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