How-To Guide Chapter 3

ManualsBrandsUBS-Axcera ManualsElectronicsLow Power Television

100 Watt High Band VHF Transmitter Chapter 3, Installation and Setup Procedures

420A, Rev. 0 3-1

Chapter 3

Installation and Setup Procedures

There are special considerations that

need to be taken into account before the

420A transmitter 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

information that will assist in planning for

the installation and set up of the

transmitter.

3.1 Site Considerations

The transmitter requires an AC input line

of 115 or 230 VAC with a rating of 10

amps. Make sure that the proposed site

for the transmitter has the voltage

requirements that are needed.

The 420A 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. Overtemperature 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 its overall

performance and reliability 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 requires temperatures in

the range of 40° F to 70° F throughout

the year, reasonably low humidity, and a

dust-free room. It should be noted that

this is rarely if ever attainable in the real

world. However, the closer your

environment is to this design, the greater

the operating capacity of the transmitter.

Although the fans and blowers designed

and built into the transmitter will remove

the heat from within the cabinet,

additional means are required for

removing heat from the building. To

achieve this, a few considerations should

be taken into account. The first step is to

determine the amount of heat to be

removed. There are generally three

sources of heat that must be considered.

The first and most obvious is the heat

from the 100-watt transmitter itself. This

can be determined by subtracting the

average power to the antenna (69.5

watts) from the input power (750 watts).

This number in watts (680.5) is then

multiplied by 3.41, which gives 2320, the

BTUs to be removed every hour.

The second source of heat is other

equipment in the same room. This

number is calculated in the same way as

the equation for BTUs. 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

Summary of content (7 pages)

PAGE 1
00 Watt High Band VHF Transmitter Chapter 3, Installation and Setup Procedures Chapter 3 Installation and Setup Procedures There are special considerations that need to be taken into account before the 420A transmitter 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.
PAGE 2
100 Watt High Band VHF Transmitter Chapter 3, Installation and Setup Procedures 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. conditions, condensation may occur on, or worse in, the transmitter. Ventilation will work if the ambient air temperature is below 100° F, or about 38° C, and the humidity is kept at a reasonable level.
PAGE 3
100 Watt High Band VHF Transmitter 5. 6. Chapter 3, Installation and Setup Procedures The exhaust should be located as high as possible. Some ducting is usually required to insure the complete flushing of heated air with no stagnant areas. falling below 40° F during transmitter operation. The filter area must be adequate to insure a maximum air velocity of 300 feet per minute through the filter. This is not a conservative number but a never-exceed number.
PAGE 4
100 Watt High Band VHF Transmitter Chapter 3, Installation and Setup Procedures Figure 3-1. 1 kW Minimum Ventilation Configuration 3.2 Unpacking the Cabinets and Trays that hold the cabinet to the shipping skid and slide the cabinet from the skid. Remove the plastic wrap and foam protection from around the cabinet. Do not remove any labeling or tags from the cabinet as well as any cables or connectors. These are identification markers which make reassembly of the transmitter much easier.
PAGE 5
100 Watt High Band VHF Transmitter Chapter 3, Installation and Setup Procedures 3.3 Installation of the Trays Not Supplied With a Cabinet tray(s) into the cabinet. Slowly slide each tray in and out to verify that they do not rub against each other and have no restrictions to free movement. Adjustments to the position of the trays may be necessary.
PAGE 6
100 Watt High Band VHF Transmitter Chapter 3, Installation and Setup Procedures Figure 3-3. Cabinet Mounting Diagram Connect the baseband video input to J2 on the rear of the tray. power raise/lower control connects to jack (J10), a 25-position, "D"-type connector, on the rear of the tray. Other remote control functions also connect to J10 and J11 of the transmitter.
PAGE 7
100 Watt High Band VHF Transmitter Chapter 3, Installation and Setup Procedures 3.4 Setup and Operation Procedures the video signal is restored, the transmitter will automatically return to Operate. Initially, the transmitter should be turned on with the RF output at the bandpass filter asssembly terminated into a dummy load with a rating of at least 100 watts. If a load is not available, check that the output is connected to the antenna.