Installing the cable and outdoor choke
I bought a 1,000 foot spool of RG-6, quad shielded CATV cable, direct burial
style, and a Thomas & Betts "Snap-n-Seal" installation tool and "F" connector
kit. In retrospect, I wish I had not gone with quad shielded direct burial cable
but instead had bought normal flooded RG-6.
The problem with quad shielded cable is that the F
connectors are difficult to install compared with standard RG-6. This is due to
the cable and connector design. F connectors have an inner stepped cylinder that
slides between the center conductor insulation and the shield, expanding the
outer layers of the cable as the connector is slid into place.
The drawings below are from the Snap-n-seal patent
application. Part 30 is the inner cylinder.
In the complete cross sectional drawing below, the
cable enters from the right side, with the inner cylinder (30) fitting between
the inner foil and the inner braid. Part 60 is the plastic compression sleeve,
which is detached from the connector during installation. Part 14b is an O-ring
to seal the connector from moisture.
The figure below shows the connector with the plastic
compression sleeve (60) detached and ready to be slid forward into the connector
body. (A special tool is used for this purpose.) When slid into the connector
body, the plastic compression sleeve forces the expanded coax layers against the
inner sleeve (30) thus making tight 360 degree connection of the shield to the
A quad shielded cable has four shields, hence the name.
- Inner foil (adhesive bonded to the center conductor
- Inner braid
- Outer foil
- Outer braid
Over the outer braid is a thin transparent film and then
the jacket. The inner cylinder of an RG-6 QS F connector slides between shields
1 and 2, i.e., between the inner foil and the inner braid. (The inner
foil is adhesively bonded to the center conductor insulation and cannot easily
be removed.) When the F connector is slid onto the cable, the inner cylinder has
to expand the inner braid, the outer foil, the outer braid, the clear film and,
finally, the jacket. Forcing the F connector onto the cable sufficiently far to
be properly seated is extremely difficult, even when the cable is prepared with
the correct tools and to the correct dimension. (Quad shielded cable has a
slightly larger outer diameter than standard RG-6. It's important to use a
RG-6QS connector, or a "universal" connector suitable for all forms of RG-6.)
Why go with RG-6 CATV cable? First, it's readily available
in direct burial construction, unlike RG-58. Second, it's relatively
inexpensive. Third, properly installed, F connectors are weather resistant. (And
the T&B Snap-n-seal connectors are excellent in this regard.) That the cable is
75 ohms impedance instead of 50 is not material for an active antenna. One other
difference is that most RG-6 cable has a copper plated steel center conductor.
This increases the DC resistance and loss at lower frequencies. These
concerns are more theoretical than practical unless your coax run is extremely
In addition to relying upon the weatherproof nature of the
Snap-n-seal connector, I also used a length of 1/2 inch adhesive lined heat
To bury the coaxial cable, I use a lawn edging tool. It cuts a narrow slit in
the soil, which I enlarge slightly by working the tool back and forth. I cut
perhaps 10 feet (3 m) of slit at a time and push cable into it.