Motorola GM340 Service Information

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Table of Contents
Chapter 1 MODEL OVERVIEW
1.0 GM140/GM340/GM640 Models...........................................................................1-1
2.0 GM160/GM360/GM660 Models...........................................................................1-1
3.0 GM380/GM1280 Models......................................................................................1-2
Chapter 2 THEORY OF OPERATION
1.0 Introduction ..........................................................................................................2-1
2.0 Controlhead Model for GM140, GM340 and GM640...........................................2-1
2.1 Power Supplies...............................................................................................2-1
2.2 Power On / Off................................................................................................2-1
2.3 Microprocessor Circuit....................................................................................2-1
2.4 SBEP Serial Interface.....................................................................................2-1
2.5 Keypad Keys...................................................................................................2-1
2.6 Status LED and Back Light Circuit .................................................................2-3
2.7 Microphone Connector Signals ......................................................................2-3
2.8 Speaker ..........................................................................................................2-4
2.9 Electrostatic Transient Protection ...................................................................2-4
3.0 Controlhead Model for GM160, GM360 and GM660...........................................2-4
3.1 Power Supplies...............................................................................................2-4
3.2 Power On / Off................................................................................................2-4
3.3 Microprocessor Circuit....................................................................................2-5
3.4 SBEP Serial Interface.....................................................................................2-5
3.5 Keypad Keys...................................................................................................2-6
3.6 Status LED and Back Light Circuit .................................................................2-6
3.7 Liquid Crystal Display (LCD) ..........................................................................2-6
3.8 Microphone Connector Signals ......................................................................2-6
3.9 Speaker ..........................................................................................................2-7
3.10 Electrostatic Transient Protection ...................................................................2-8
4.0 Controlhead Model for GM380 and GM1280.......................................................2-8
4.1 Power Supplies...............................................................................................2-8
4.2 Voltage Regulator Circuit................................................................................2-8
4.3 Power On / Off................................................................................................2-9
4.4 Microprocessor Circuit....................................................................................2-9
4.5 SBEP Serial Interface...................................................................................2-10
4.6 Keypad Keys.................................................................................................2-10
4.7 Status LED and Back Light Circuit ...............................................................2-10
4.8 Liquid Crystal Display (LCD) ........................................................................2-11
4.9 Microphone Connector Signals ....................................................................2-11
4.10 Speaker ........................................................................................................2-12
4.11 Electrostatic Transient Protection .................................................................2-12

Motorola GM340 Specifications

General

Channel Capacity	16 channels
Power Output	1-25 W (VHF), 1-25 W (UHF)
Weight	1.4 kg
Operating Temperature	-30°C to +60°C
Channel Spacing	12.5/20/25 kHz
Frequency Range	136-174 MHz (VHF), 403-470 MHz (UHF)
Modulation	16K0F3E, 11K0F3E