Service manual

vii
Table of Contents
Chapter 1 Introduction
1.1 Scope of Manual ........................................................................................................... 1-1
1.2 Warranty and Service Support..................................................................................... 1-1
1.2.1 Warranty Period................................................................................................................... 1-1
1.2.2 Return Instructions .............................................................................................................. 1-1
1.2.3 After Warranty Period .......................................................................................................... 1-1
1.3 Related Documents ...................................................................................................... 1-2
1.4 Technical Support......................................................................................................... 1-2
1.4.1 Piece Parts Availability ........................................................................................................ 1-2
1.5 Radio Model Chart and Specifications........................................................................ 1-3
1.6 Radio Model Information.............................................................................................. 1-3
Chapter 2 Theory of Operation
2.1 Introduction ................................................................................................................... 2-1
2.2 Radio Power Distribution ............................................................................................. 2-1
Figure 2-1:DC Power Distribution Block Diagram ............................................................. 2-1
2.3 Keypad ........................................................................................................................... 2-2
Figure 2-2:Keypad Block Diagram .................................................................................... 2-2
2.4 Controller Board ........................................................................................................... 2-3
Figure 2-3:Controller Block Diagram................................................................................. 2-3
2.4.1 MCU Digital ......................................................................................................................... 2-3
2.4.1 Real Time Clock .................................................................................................................. 2-4
2.4.2 Circuit Description ............................................................................................................... 2-4
Figure 2-4:RTC Circuit ...................................................................................................... 2-4
2.4.1 MODB/VSTBY Supply ......................................................................................................... 2-4
2.4.1 Audio/Signaling.................................................................................................................... 2-5
2.5 UHF Transmitter............................................................................................................ 2-5
Figure 2-5:UHF Transmitter Block Diagram...................................................................... 2-5
2.5.1 Power Amplifier (PA) ........................................................................................................... 2-5
2.5.2 Antenna Switch.................................................................................................................... 2-6
2.5.3 Harmonic Filter .................................................................................................................... 2-6
2.5.4 Antenna Matching Network ................................................................................................. 2-6
2.5.5 Power Control Integrated Circuit (PCIC) ............................................................................. 2-6
2.5.6 Temperature Cut Back Circuit ............................................................................................. 2-6
2.6 UHF Receiver.................................................................................................................2-6
Figure 2-6:UHF Receiver Block Diagram.......................................................................... 2-7
2.6.1 Receiver Front-End ............................................................................................................. 2-7
2.6.2 Receiver Back-End.............................................................................................................. 2-8
2.6.3 Automatic Gain Control (AGC) ............................................................................................ 2-8
2.6.4 Frequency Generation Circuit.............................................................................................. 2-9
Figure 2-7:UHF Frequency Generation Unit Block Diagram............................................. 2-9
2.7 Synthesizer.................................................................................................................... 2-9
Figure 2-8:UHF Synthesizer Block Diagram ................................................................... 2-10
2.8 Voltage Control Oscillator (VCO)............................................................................... 2-10
Figure 2-9:UHF VCO Block Diagram .............................................................................. 2-11