Table of Contents v
Table of Contents
Copyright ........................................................................................................ i
Safety Information......................................................................................... ii
Document History ........................................................................................ iii
Chapter 1 Maintenance ........................................................................ 1-1
1.1 Preventive Maintenance ................................................................................................................ 1-1
1.2 Inspection ...................................................................................................................................... 1-1
1.3 Cleaning......................................................................................................................................... 1-1
1.4 Safe Handling of CMOS and LDMOS............................................................................................ 1-2
1.5 General Repair Procedures and Techniques ................................................................................ 1-2
Chapter 2 Test Equipment, Service Aids, and Service Tools........... 2-1
2.1 Test Equipment.............................................................................................................................. 2-1
2.2 Service Aids................................................................................................................................... 2-2
Chapter 3 DC Power Distribution........................................................ 3-1
3.1 DC Regulation and Distribution ..................................................................................................... 3-1
Chapter 4 Controller Theory of Operation.......................................... 4-1
4.1 RX Audio Circuit ............................................................................................................................ 4-1
4.1.1 Audio processor IC (U102) ............................................................................................... 4-1
4.1.1.1 RX Audio Processing......................................................................................... 4-1
4.1.1.2 RX Tone PL/Digital PL Decode Filtering............................................................ 4-2
4.1.2 Audio Amp ........................................................................................................................ 4-2
4.1.3 Internal and External Speaker .......................................................................................... 4-2
4.2 TX Audio Circuit............................................................................................................................. 4-3
4.2.1 MIC and External MIC ...................................................................................................... 4-3
4.2.2 4-order 4 kHz Low-Pass Filter (U501-C, D) ...................................................................... 4-3
4.2.3 Audio processor IC (U102) ............................................................................................... 4-3
4.2.3.1 TX Audio Processing ......................................................................................... 4-3
4.2.3.2 Tx Tone PL/Digital PL Encode Filtering............................................................. 4-4
4.2.4 TX audio amplifier and 6 order 3 kHz Low-Pass filter....................................................... 4-4
4.2.5 TX modulation Adjustment................................................................................................ 4-4
4.3 Microprocessor Circuitry ................................................................................................................ 4-4
4.3.1 Memory Usage ................................................................................................................. 4-5
4.3.2 Control and Indicator Interface ......................................................................................... 4-5
4.3.3 Interface to USB programming ......................................................................................... 4-5
4.3.4 Storage of Customer-Specific Information........................................................................ 4-5
4.3.5 Sensing of VOX operating ................................................................................................ 4-5
4.3.6 Microprocessor Power-on reset Routine .......................................................................... 4-5
4.3.7 Microprocessor 7.3728 MHz Clock................................................................................... 4-5
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