Motorola EP350 User Manual

vi Table of Contents
4.3.8 Battery indicator ................................................................................................................ 4-5
Chapter 5 435 – 480 MHz UHF2 Theory Of Operation ....................... 5-1
5.1 Introduction ....................................................................................................................................5-1
5.2 UHF2 Receiver ..............................................................................................................................5-1
5.2.1 Receiver Front End ...........................................................................................................5-2
5.2.2 Receiver Back End ........................................................................................................... 5-2
5.3 UHF2 Transmitter .......................................................................................................................... 5-3
5.3.1 Power Amplifier................................................................................................................. 5-3
5.3.2 Antenna Switch .................................................................................................................5-3
5.3.3 Harmonic Filter.................................................................................................................. 5-3
5.3.4 Auto Power Control...........................................................................................................5-4
5.4 UHF2 Frequency Generation Circuitry........................................................................................... 5-4
5.4.1 Reference Oscillator (12.8 MHz VCTCXO).......................................................................5-4
5.4.2 PLL IC Prescaler and Comparator.................................................................................... 5-5
5.4.3 Voltage Doubler and Charge Pump ..................................................................................5-5
5.4.4 Loop Filter .........................................................................................................................5-5
5.4.5 Dual VCO.......................................................................................................................... 5-5
5.5 Keypad...........................................................................................................................................5-6
Chapter 6 UHF2 Troubleshooting Tables........................................... 6-1
6.1 Troubleshooting Table for Receiver (UHF2) ................................................................................. 6-1
6.2 Troubleshooting Table for Synthesizer (UHF2) ............................................................................ 6-2
6.3 Troubleshooting Table for Transmitter (UHF2) .............................................................................6-3
6.4 Troubleshooting Table for Board and IC Signals (UHF2) ............................................................. 6-4
Chapter 7 UHF2 Schematic Diagrams, Overlays, and Parts Lists ... 7-1
7.1 Introduction ....................................................................................................................................7-1
7.1.1 Notes For All Schematics and Circuit Boards ...................................................................7-1
7.1.2 Four Layer Circuit Board...................................................................................................7-3
7.2 Speaker and Microphone Schematic .............................................................................................7-3
7.2.1 Speaker and Microphone Parts List..................................................................................7-3
7.3 Circuit Board/Schematic Diagram and Parts List (UHF2: 435–480 MHz)...................................... 7-4
7.3.1 Parts List .........................................................................................................................7-16
Chapter 8 136 – 174 MHz VHF Theory Of Operation.......................... 8-1
8.1 Introduction ....................................................................................................................................8-1
8.2 VHF Receiver................................................................................................................................. 8-1
8.2.1 Receiver Front End ...........................................................................................................8-2
8.2.2 Receiver Back End ........................................................................................................... 8-2
8.3 VHF Transmitter.............................................................................................................................8-3
8.3.1 Power Amplifier................................................................................................................. 8-3
8.3.2 Antenna Switch .................................................................................................................8-3
8.3.3 Harmonic Filter.................................................................................................................. 8-3
8.3.4 Auto Power Control...........................................................................................................8-4
8.4 VHF Frequency Generation Circuitry.............................................................................................8-4
8.4.1 Reference Oscillator (12.8 MHz VCTCXO).......................................................................8-4
8.4.2 PLL IC Prescaler and Comparator.................................................................................... 8-5

Motorola EP350 Specifications

General

Channel Capacity	16 channels
IP Rating	IP54
Drop Resistance	1.2 meters
Frequency Range	VHF: 136-174 MHz, UHF: 403-470 MHz
Battery Life	Up to 11 hours
Power Supply	7.5 V (Nominal)
Waterproof	Splashproof
Dimensions	127.6 x 62 x 42 mm (with standard battery)