User Manual
Table Of Contents
- 1GENERAL
- 1.1Introduction
- 1.2Manual Organization
- 1.3VT-4B 136 - 174 MHz Transmitter Family Models
- 1.4Performance Specifications
- 1.4.1General
- 1.4.2Audio Specifications
- 1.4.3Physical Specifications
- 2THEORY OF OPERATION
- 2.1Transmitter Operation
- 2.2Transmitter Programming
- 2.2.1Transmitter Wide Options
- 2.2.1.1Disable Front Panel Led
- 2.2.1.2Secure Hardware Equipped
- 2.2.1.3Allow Emergency Transmissions
- 2.2.1.4Allow Radio Inhibit
- 2.2.1.5Allow Radio Check
- 2.2.1.6Enable Status
- 2.2.1.7Frequency Band
- 2.2.2Channel Wide Settings
- 2.2.2.1Frequency
- 2.2.2.2Voice/Signal Type
- 2.2.2.3Squelch Type
- 2.2.2.4CTCSS Tone
- 2.2.2.5Enable Reverse Burst
- 2.2.2.6DCS Code
- 2.2.2.7DCS Invert
- 2.2.2.8Enable Turn Off Code
- 2.2.2.9Transmitter Power
- 2.2.2.10Channel Bandwidth
- 2.2.2.11Deviation
- 2.2.2.12Time Out Timer
- 2.2.2.13Channel Status
- 2.2.2.14Transmitter Pre-emphasis
- 2.2.2.15NAC Transmitter Code
- 2.2.2.16NAC Transmitter
- 2.3Transmitter Programming using Motorola Radio Service Software
- 2.4Secure Communications
- 2.5Transmitter Assembly and Adjustment
- 2.5.1Controller Board Alignment
- 2.5.1.1Reference Oscillator Adjustment
- 2.5.1.2Transmitter Deviation Balance Adjustment
- 2.5.1.3Transmitter Deviation Limit Adjustment
- 2.5.2Amplifier Alignment
- 2.5.3Frequency Change
- 2.6Recommended Test Equipment List
- 2.7Repair Note
- 2.8Printed Circuitboard Numbering Convention
- 3ILLUSTRATIONS
- 3.1MT-4 Base Transmitter Front Panel
- 3.2MT-4 Transmitter Case - Exploded View
- 3.3Digital Base Transmitter Block Diagram
- 3.4Digital Base Transmitter Schematic Diagram
- 3.5Digital Base Transmitter Main Board Component Layout (Bottom)
- 3.6Digital Base Transmitter Main Board Component Layout (Top)
- 4PARTS LIST
- 4.1P25 Base Transmitter Main Board Parts List
- 4.1.1P25 Base Transmitter Main Board Electrical Parts List
- 4.1.2P25 Base Transmitter Mechanical Parts List
- 5REVISION HISTORY
DE
DANIELS
ELECTRONICS
VT-4B150 VHF Project 25
Digital
Base
Transmitter
Instruction
Manual
2-9
2.7 Repair Note
The transmitter is mainly made up of surface mount devices that should not be removed or replaced
using an ordinary soldering iron. Removal and replacement of surface mount components should
be performed only with specifically designed surface mount rework and repair stations complete
with ElectroStatic Discharge (ESD) protection.
When removing Surface Mount Solder Jumpers, it is recommended to use solder braid in place of
manual vacuum type desoldering tools when removing jumpers. This will help prevent damage to
the circuit boards.
2.8
Printed Circuitboard Numbering Convention
To ease troubleshooting and maintenance procedures, Daniels Electronics Limited has adopted a
printed circuitboard (PCB) numbering convention in which the last two digits of the circuitboard
number represent the circuitboard version. For example:
• PCB number 43-9120
10
indicates circuitboard version 1.0;
• PCB number 50002-
02
indicates circuitboard version 2.0.
All PCB's manufactured by Daniels Electronics are identified by one of the above conventions.