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MOUNTING SITES AND RELATED
PROCEDURES
Attic Installations
An attic installation (Figure 4-3) may work in areas
where strong signals are present. In most cases, an
attic installation is the easiest, fastest, most
economical, and most convenient installation. There
are a few conditions however that can prohibit an
attic installation. Shallow attics that are obstructed
by rafter supports may not accommodate the size
antenna required for the installation. Most attics are
not large enough to accommodate multi-antenna
arrays and rotors. Also, aluminum foil on insulation,
aluminum or steel siding, metal gutters at the attic
level, and metal lath under older plaster walls all can
interfere to some degree with reception.
Fig. 4-3. A typical attic installation.
To determine if an attic installation is suitable, take a
test antenna, a field-strength meter and a portable TV
up into the attic and check the signal level and
picture quality. If the signal level is sufficient and
there is room enough to properly orient the antenna,
assemble the antenna in the attic and attach one end
of the transmission line to the antenna terminals.
Then prepare the mount for the antenna.
Several roof-type mounting brackets (Figure 4-4) and
swivel mounts (Figure 4-5) are adaptable for use in
attic installations. The mounting bracket is used to
attach the short mast to a rafter or rafter support.
The antenna is then mounted on the other end of the
mast. The antenna however, must not touch the attic
floor. Also, remember that the antenna should be
attached to the mast right side up, even though the
installation appears to be the reverse of an outside
installation.
T
M
OOLS,
ASTS &
Fig. 4-4.
Examples of swivel mounts that can be used in attic installations.
An alternative method of mounting the mast is to
flatten one end of the mast with a hammer and drill a
hole in it through which a nail, screw, or bolt can be
inserted for securing the mast to a rafter or rafter
support. However, this method requires more time
and effort than does the bracket method.
Instead of using a mast, you may suspend the antenna
from the inside of the roof with guy wires or nylon
rope. But don't let the guy wires touch the antenna
elements. They will short out the antenna.
Once you have the antenna mounted or suspended,
you are ready to run the transmission line. If at all
possible, keep it indoors. Coaxial cable (Figure 4-6) is
the best transmission line for any antenna installa-
tion. It should be used instead of twinlead even in
attic installations. Selection and installation of the
correct transmission line is described in the chapter
beginning on page 15.
Fig. 4-6. Coaxial cable, the preferred type of TV transmission line.
After you have run the transmission line, use a
compass and field-strength meter to orient the
antenna toward the signal source(s). Check the
picture and sound on all channels before you tighten
down the clamp that secures the antenna to the mast.
Some manufacturers make special antennas for attic
installations. These antennas however, tend to be
omni-directional. This means they intercept signals
equally well from all directions. Consequently, they
will also pick up interference more readily than a
good directional antenna.
HA
RDWARE
Fig. 4-5.
R
EQUIREMENTS
9
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