Codan Radio Communications VT-3H040-S-HSO User Manual
Transmitter Main Board Instruction Manual IM20-MT3TXMN
iii
TABLE OF CONTENTS
1
GENERAL .......................................................................................................................1-1
1.1
Introduction............................................................................................................1-1
1.2
Performance Specifications....................................................................................1-1
1.2.1
General Specifications......................................................................................1-1
1.2.2
Audio Specifications ........................................................................................1-2
2
THEORY OF OPERATION............................................................................................2-1
2.1
Transmitter Main Board.........................................................................................2-1
2.1.1
General Theory of Operation ...........................................................................2-1
2.1.2
Transmitter Push-To-Talk................................................................................2-1
2.1.2.1
Microphone PTT .........................................................................................2-1
2.1.2.2
PTT With Time-Out-Timer..........................................................................2-2
2.1.2.3
PTT No Time-Out-Timer.............................................................................2-2
2.1.2.4
PTT Relay....................................................................................................2-2
2.1.2.5
PTT Output..................................................................................................2-3
2.1.2.6
PTT Voltage Switching................................................................................2-3
2.1.3
Transmitter Standby Modes.............................................................................2-4
2.1.3.1
Audio Circuits..............................................................................................2-6
2.1.3.2
Microphone Audio.......................................................................................2-6
2.1.3.3
Received Audio............................................................................................2-6
2.1.4
Channel Selection.............................................................................................2-6
2.1.4.1
Synthesized Transmitter...............................................................................2-6
2.1.4.2
Crystal Controlled Transmitter.....................................................................2-7
2.1.5
Amplifier Circuits.............................................................................................2-7
2.1.6
Time-Out-Timer Circuitry................................................................................2-8
2.1.6.1
Optional Time-Out Timer on the Audio Processor Board............................2-8
2.2
MT-3 Front Panel Board........................................................................................2-10
2.3
Version 1.8 Audio Processor .................................................................................2-11
2.3.1
General.............................................................................................................2-11
2.3.2
Power Requirements ........................................................................................2-11
2.3.3
Audio Processor Turn-on Time........................................................................2-12
2.3.4
Audio Processor Signals..................................................................................2-12
2.3.4.1
Audio Processor Outputs.............................................................................2-12
2.3.4.2
Audio Processor Modulation Output...........................................................2-12
2.3.4.3
Audio Processor Low Frequency / Direct Mod. Output ..............................2-13
2.3.4.4
Audio Processor Inputs ...............................................................................2-13
2.3.4.5
Audio Processor Microphone Input.............................................................2-13
2.3.4.6
Audio Processor Balanced Input..................................................................2-13
2.3.4.7
Audio Processor Auxiliary Input .................................................................2-14
2.3.4.8
Audio Processor Subtone Inputs .................................................................2-14
2.3.4.9
Audio Processor Direct Modulation Input...................................................2-14