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Theory Of Operation; Introduction; Vhf (136-162Mhz) Receiver - Motorola Commercial Series Service Information

Vhf1 136-162mhz

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Basic service manual (100 pages)

Basic user's manual (86 pages)

Selling manual (66 pages)

Table Of Contents

Table of Contents

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

VHF (136-162MHz) Receiver

The VHF receiver covers the range of 136-162 MHz and provides switchable IF bandwidth for use

with 20/25/30 kHz or 12.5 kHz channel spacing systems. The receiver is divided into two major

blocks, as shown in Figure 2-1.

■

Front End

■

Back End

RX from

Antenna Switch

Preselector

Filter

Amp

First LO

from Synthesizer

Recovered Audio

RSSI

Figure 2-1 VHF Receiver Block Diagram