350-Watt Digital VHF LB Transmitter
Chapter 3, Installation and Setup Procedure
DT325B, Rev. 0
3-1
Chapter 3
Installation and Setup Procedures
There are special considerations that
need to be taken into account before the
DT325B can be installed. For example, if
the installation is completed during cool
weather, a heat-related problem may not
surface for many months, suddenly
appearing during the heat of summer.
This section provides planning
information for the installation and set up
of the transmitter.
3.1 Site Considerations
The transmitter requires an AC input line
of 220 VAC with a rating of 30 amps
connected to the AC input box on the
cabinet. Make sure that the proposed
site for the transmitter has the voltage
requirements that are needed.
The DT325B is designed and built to
provide long life with a minimum of
maintenance. The environment in which
it is placed is important and certain
precautions must be taken. The three
greatest dangers to the transmitter are
heat, dirt, and moisture. Heat is usually
the greatest problem, followed by dirt,
and then moisture. Over-temperature
can cause heat-related problems such as
thermal runaway and component failure.
Each amplifier tray in the transmitter
contains a thermal interlock protection
circuit that will shut down that tray until
the temperature drops to an acceptable
level.
A suitable environment for the
transmitter can enhance the overall
performance and reliability of the
transmitter and maximize revenues by
minimizing down time. A properly
designed facility will have an adequate
supply of cool, clean air, free of airborne
particulates of any kind, and without
excessive humidity. An ideal environment
will require temperature in the range of
40° F to 70° F throughout the year,
reasonably low humidity, and a dust-free
room. This is rarely attainable in the real
world. However, the closer the
environment is to this design, the greater
the operating capacity of the transmitter.
The first source of heat in the building is
the transmitter itself. The fans designed
and built into the transmitter will remove
the heat from within the trays and
cabinets, but additional means are
required for removing this heat from the
building. Two blowers, one mounted on
the roof of each cabinet, are designed to
achieve this.
The second source of heat is other
equipment in the same room. The third
source of heat is equally obvious but not
as simple to calculate. This is the heat
coming through the walls, roof, and
windows on a hot summer day. Unless
the underside is exposed, the floor is
usually not a problem. Determining this
number is usually best left up to a
qualified HVAC technician. There are far
too many variables to even estimate this
number without detailed drawings of the
site showing all construction details. The
sum of these three sources is the total
amount of heat that must be removed.
There may be other sources of heat, such
as personnel, and all should be taken into
account.
Now that the amount of heat that must
be removed is known, the next step is to
determine how to accomplish this.
The options are air conditioning,
ventilation, or a combination of the two.
Air conditioning is always the preferred
method and is the only way to create
anything close to an ideal environment.
Ventilation will work quite well if the
ambient air temperature is below 100° F,
or about 38° C, and the humidity is be
kept at a reasonable level. In addition,
the air stream must be adequately
