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Note: Always make a drip loop (Figure 5-9) at the
entry point so that water will run off the line and not
into the house.
If you are running the line through wooden siding,
drill a hole through the wall, run the line through and
then seal the entry point with caulking compound for
weather protection.
Fig. 5-9. A drip loop prevents water from running along the
cable and into the house wall.
For an entry through brick, concrete, or stucco, use a
hammer and star bit or a carbide-tip masonry drill
bit. Again, caulking should be used to weatherproof
the entry.
CAUTION: Before making an entry hole, always
carefully check the interior surface of the wall for
electrical fixtures or wiring that may be in the path of
the drill bit. Do not enter near electrical wires or
outlets especially when using twinlead.
Indoor runs of transmission line should be concealed
as much as possible. With twinlead this is a practical
necessity because it should be shielded from unwanted
signals whenever possible. Coax should be concealed
too, but mostly for neatness. If possible, run the line
in closets, behind walls, behind baseboards and
moldings, or up through the floor from the basement.
Snaking the line down between wall studs however, is
difficult and time consuming. Consequently, it shouldn't
be done unless the customer has demanded it and
has agreed to pay the extra cost. Before attempting to
conceal the line behind baseboards and moldings, be
sure that you can replace them exactly as they were
without damage.
S
ELECTING &
18
I
T
NSTALLING
RANSMISSION
There are various couplers, amplifiers, and wall
outlets that are useful in many installations. Because
these
devices
usually
instructions, their installation will not be described in
detail here. However, we suggest the following
general procedures and guidelines:
1. Use only plastic outlet boxes or plaster straps for
300 ohm twinlead.
2. Locate TV outlets near electrical outlets. However,
avoid running twinlead parallel to the electrical
wiring in the wall. (Coax is not affected by the
electrical wiring because it is shielded.
3. When running transmission line from a coupler or
amplifier, be sure it runs to the outlet(s) as directly
as possible. The shorter the run the better.
4. Twinlead lines running in and out of any device
should never be run close or parallel to each other.
5. If you must use twinlead outdoors, select the kind
with a black polyethylene jacket. The sun's
ultra-violet rays will not penetrate it, and it will not
crack or chip in extreme heat.
Choosing the correct type and best quality of
transmission line and then installing it correctly, is
one of the keys to a customer-pleasing TV antenna
installation. Don't skimp on quality. "Cheap"
transmission line can be very costly in the long run.
Most so-called "cheap" lines not only produce
excessive attenuation and poor impedance matching,
but also are made of poor grade polyethylene which
deteriorates rapidly. This makes it necessary to
replace an installation within a relatively short
time. Because the dollar difference between "cheap"
and quality line is minimal, it always pays to invest in
the best.
L
INE
come
with
detailed
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