DE
DANIELS
ELECTRONICS
VT-4R150 VHF Project 25 Digital Transmitter Instruction Manual
1-1
1
GENERAL
1.1
Introduction
The VT-4R150 Project 25 Digital Transmitters are low current, synthesized FM Transmitters
capable of analog or Project 25 digital operation in 12.5 kHz (narrow band) or 25 (wide band)
channels. They operate over the bands from 136-150 and 150-174 MHz. Modular design allows
each of the Transmitter’s internal modules to be individually assembled and tested, which
facilitates construction, tuning, and general Transmitter maintenance.
The VT-4R150 Transmitter combines state of the art performance in a compact modular enclosure
for applications ranging from remote mountain top repeaters to congested urban radio
environments. Each Transmitter module is characterized by dependable, low maintenance
performance under the most severe environmental conditions.
The VT-4R150 Transmitter is compatible with all Daniel’s subrack and base station enclosures. It
supports a basic analog interface, and may be used in a mixed system with MT-2 and MT-3 series
Receivers and Transmitters.
1.2
Interim Operation
Although the VT-4R150 family of transmitters can generate Project 25 voice transmissions, it
cannot currently be used to create a fully compliant Project 25 repeater. All hardware necessary to
enable a fully compliant Project 25 transmitter is present, however a firmware upgrade will be
required to achieve this capability. In its Interim Operation mode, the transmitter can accept
baseband audio and remodulate it as a FM analog or Project 25 digital signal. In a repeater made
up of and interim Receiver and Transmitter, a voice signal will be repeated in either mode, but
other Project 25 digital information such as Network Addressing Code, Talk Group ID, and low
speed data will be lost.
1.3
Manual Organization
The organization of this document reflects the modular construction of the VT-4 family of
products. Each product is fully described within its respective "sub-manual"; all of which are
contained within this document. In general, each of these sub-manuals contain:
1. A functional description and specification summary.
2. A detailed technical description (Theory of Operation).
3. Assembly, setup and alignment procedures relevant to the particular module.
The following sub-manual is contained within this document cluster:
VHF
Amplifier
Instruction
Manual
: This manual provides information on alignment and operation
of the 2 and 8 Watt RF amplifier modules.
The following manual is also required for alignment of the VT-4 family transmitter.
Radio
Service
Software
M
anual
: This manual provides instructions on using the PC-based Radio
Programming Software package to perform Transmitter alignment and frequency and mode
selection. This manual is available as a PDF file on CD that is supplied in the Radio Service
Software and Interface Kit.