Codan Radio Communications VT 3H040 S Users manual

DANIELS
ELECTRONICS LTD. ®

MT-3 RADIO SYSTEMS

VHF TRANSMITTER

INSTRUCTION MANUAL

VT-3

29 - 50 MHz

Covers model: VT-3H035-SWA3, VT-3H045-SWA3

Copyright © 1997 Daniels Electronics Ltd. All rights reserved. No part of this publication may be
reproduced, stored in a retrieval system or transmitted in any form or by any means, electronic,
mechanical, photocopying, recording or otherwise, without the prior written consent of Daniels
Electronics Ltd.

Issue: 1 Previous Issue: N/A
Issue Date: May 97 Previous Issue Date: N/A Daniels Electronics Ltd.
Printing Date: Sept 97 Victoria, B.C.
Part No.: IM20-VT3040 PRINTED IN CANADA

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1 GENERAL

1.1 Introduction

The VT-3H040 transmitter is a low power, synthesized FM transmitter capable of operating in
20 kHz or 25 kHz channels and within one of two bands: 29 MHz to 38 MHz or 38 MHz to 50
MHz. The transmitter is rated for continuous duty at an RF output power of 3.0 Watt. The RF
output power level is preset at the factory. A modular design allows each of the transmitter's
modules; MT-3 Transmitter Main Board, MT-3 Audio Processor, VT-3H040 Amplifier and OS­3H040 Synthesizer to be individually assembled and tested. This facilitates construction, tuning,
maintainance as well as troubleshooting procedures. The synthesizer module can be programmed
to have up to 16 channels exclusive to one frequency band.

The VT-3H040 Transmitter is designed to interface with Daniels Electronics' MT-3 Repeater
System while maintaining MT-2 System compatibility. Both radio systems are characterized by
dependable, low maintanence performance under the most severe environmental conditions.

1.2 Manual Organization

The organization of this manual reflects the modular makeup of the VT-3 product line. Each
module is fully described within its respective submanual, all of which are contained within this
document. In general, each submanual contains:

1. A functional description and specification summary,

2. a detailed technical description (Theory of Operation) and

3. assembly, setup and alignment procedures relevent to that particular module.

The module manuals are as follows.

Note: material presented in a given "sub-manual" may include information related to other
module versions not directly appllicable to the VT-3H040 Transmitter family (eg, the OS-3H
Synthesizer Instruction Manual covers models from 29 MHz to 512 MHz).

Transmitter Manual: This manual provides an overview of the complete transmitter, manual
organization and assembly in terms of the other modules.

MT-3 Transmitter Main Board: This manual pertains to the audio processor module, transmitter
Main Board and Front Panel Board. Most of the user selectable options are accessed within the
Transmitter Main Board module, including channel selection. Since all external connections
(including power and signal lines) are made to the Transmitter Main Board, most of the material
pertaining to transmitter operation and installation is found here.

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VT-3H040 VHF Enhanced Transmitter Instruction Manual 1-1

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VT-3H040 VHF Amplifier: The amplifier module provides the final stages of RF power
amplification and harmonic filtering for the transmitter. This manual is intended primarily as a
reference since the amplifier module is adjusted at the factory.

OS-3H040 Synthesizer: This manual pertains to the synthesizer module. Channel selection is
described in the 'Transmitter Main Board' Manual.
VT-3H040 Channel Designation Table: This document relates operating frequency to the
transmitter channel number (see section 2.1).

1.3 VT-3H040 Transmitter Family Models

The VT-3H040 line of transmitters has a single RF power output rating of 3.0 Watt, with wide
band FM (20 kHz or 25 kHz channels) and employs synthesizer based frequency generation. The
two basic (i.e. no options added) band specific models of the transmitter are as follows:

VT-3H035-SWA3: 29 MHz to 38 MHz
VT-3H045-SWA3 38 MHz to 50 MHz

The frequency is determined by the model of synthesizer and by the lowpass filter that is installed
in the amplifier module (see the VT-3H040 VHF Amplifier manual for details). A group of
channels spanning 38 MHz can be accomodated by one of the models providing that the
frequency span does not exceed 1.0 MHz. Model VT-3H035-SWA3 can operate at frequencies
up to 38.5 MHz and is the preferred choice when spanning 38 MHz. Consult the factory for
futher information regarding operation around this frequency.

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ELECTRONICS

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1.4 Performance Specifications

1.4.1 General

The following is a general set of specifications for the generic VT-3H040 transmitter. Additional
specifications, specific to individual modules may be found in their respective submanuals.

Type: MT-3 Series Transmitter

Family: VT-3H040

Compatibility: MT-2 Series and MT-3 Series Radio Systems

Frequency Range: 29.0 MHz to 50.0 MHz

RF Power Output: 3.0 Watt Fixed (± 1.5 dB with temperature and

supply voltage).

System Impedance: 50  ; Type N connector.

Duty Cycle: 100%: Continuous operation from -30˚ C to +60˚C

(optional -40˚ C to +60˚C).

Harmonic Emissions: More than 90 dB below carrier.

Spurious Emissions: More than 80 dB below carrier.

Transmitter Mismatch Protection: 20:1 VSWR at all phase angles.

Transmitter Alarm: Forward power sense and reverse VSWR;

- open collector output (separate or 'OR'ed);

- linear output (separate lines only).

Modulation: 16K0F3E

Synthesizer Reference Frequency: 9.600000 MHz or 10.000000 MHz ; selectable.

Channel Spacing: 20 / 25 kHz

Frequency Stability: Standard: ±1 ppm, -30˚C to +60˚C,

optional -40˚C to +60˚C

Channel Selection: In 5 kHz or 6.25 kHz increments selected through

four internal BCD rotary switches. Preset capability
for 16 channel memory selectable through external
control.

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ELECTRONICS

VT-3H040 VHF Enhanced Transmitter Instruction Manual 1-3