vi Table of Contents
4.3.8 Battery indicator ................................................................................................................ 4-6
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 ........................................................................................................... 5-3
5.3 UHF2 Transmitter .......................................................................................................................... 5-3
5.3.1 Power Amplifier................................................................................................................. 5-4
5.3.2 Antenna Switch ................................................................................................................. 5-4
5.3.3 Harmonic Filter.................................................................................................................. 5-4
5.3.4 Auto Power Control........................................................................................................... 5-4
5.4 UHF2 Frequency Generation Circuitry........................................................................................... 5-5
5.4.1 Reference Oscillator (12.8 MHz VCTCXO)....................................................................... 5-5
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 ......................................................................................................................... 5-6
5.4.5 Dual VCO.......................................................................................................................... 5-6
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)...................................... 7-5
7.3.1 Parts List ......................................................................................................................... 7-20
7.4 Circuit Board/Schematic Diagram and Parts List (UHF2 R&TTE: 435–470 MHz)....................... 7-29
7.4.1 Parts List ......................................................................................................................... 7-44
7.5 Circuit Board/Schematic Diagram and Parts List (UHF2: 435–480 MHz).................................... 7-53
7.5.1 MDC1200 and QCII Models............................................................................................ 7-53
7.5.2 Parts List (MDC 1200 and QCII) .................................................................................... 7-66
7.6 Circuit Board/Schematic Diagram and Parts List UHF2 - MDC/QCII R&TTE (435–470 MHz) .... 7-79
7.6.1 Parts List UHF2 MDC/QCII R&TTE (435–470 MHz) ...................................................... 7-91
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