Installation guide

MULTI-SET RECEPTION
28
Before attempting multi-set reception with passive
devices, use a field-strength meter to measure the
signal strength at the receiver end of the main trans-
mission line. If it is less than 2000 microvolts (uV) and
you need to feed three sets, you will have to increase
the signal level. To do this, you will have to use one of
the following methods:
• A higher gain antenna
• A mast-mounted preamplifier (preamp)
• Both a higher gain antenna and a preamp
• An Amplified Coupler
Amplifiers
When signal levels are weak, a preamplifier (Figure
10-4a) should be used as this will give the lowest
system noise figure. A distribution amplifier (Figure
10-4b) is a type of amplifier that is mounted indoors,
usually in a central location. It is designed to provide
amplified signals to a number of TV sets. The term
“amplified” means that the strength of the signal is
increased by electronic circuits called amplifiers. See
the Channel Master catalog for models.
The distribution amplifier should be mounted in a
relatively central location so that the coaxial cables
(through which it feed signals to TV sets) are the
same length. This will help ensure that all TV sets
receive the same strength of signals.
In areas with very weak signals you will need to use
both a mast-mounted preamp and a distribution
amplifier. However, be sure the two amplifiers are
matched. The term “matched” means that the
electronic characteristics of the two amplifiers are
similar enough to permit using them together without
causing interaction and reducing picture quality.
A signal-distribution system that is equipped with a
matched pair of amplifiers is called a tandem system.
The matched amplifiers are called “tandem units.”
See the Channel Master catalog for models.
MATV Systems
“MATV” means Master Antenna Television (system).
A home MATV system is an expanded version of the
multi-set reception systems described previously. It is
used to distribute the signals from one antenna (or
antenna array) to a number of wall outlets located at
convenient points in all or most rooms of the house.
The components and distribution network of a typical
medium-size home MATV system are shown in Figure
10-5. The antenna signals are fed through coaxial
cable to a distribution amplifier. This amplifier
increases the strength of the signals and then splits
them into two or more outputs. The signals at these
outputs are fed through coaxial cable to conveniently
located splitters. The splitters, in turn, divide the
main branches into subbranches, which feed the wall
outlets in one or two rooms. Coaxial cable is used
throughout the system. Ideally, a home MATV system
should be installed while the house is being built,
so that the cables can be conveniently run inside the
walls. However, a MATV system can also be installed
in a finished house by feeding the cables into the
wall spaces through holes drilled in the attic floor
above the spaces. The cable-entry holes also can be
drilled through the main floor from the basement or
crawl space.
A home MATV system can be expanded to provide
closed-circuit TV surveillance of various outdoor and
indoor areas, including nurseries, playrooms, and
house entrances. It also can be used to distribute
Cable TV or Community Antenna Television (CATV)
signals throughout the house.
MATV is relatively easy to install. Don’t hesitate to
suggest MATV to your customers. Most probably do
not know about MATV and the convenient, high-quality
reception that it provides for a relatively small invest-
ment. You can substantially enhance your reputation
and your profits by providing MATV sales, installa-
tion, and service to both homes and businesses.
MATV for business is no more difficult to plan and
install than that used in large houses.
Fig. 10-4a. Channel Master
®
Preamplifier.
Fig. 10-4b. When many outlets (more than 4) are required,
a distribution amplifier should be used.