So if we use perforated pipe, don't we still need coax
that is designed to be buried since the coax will be
wet (since the ground is wet all winter when it
Since the moisture can drain out, there will
presumably be times when the coax is dry. But there
will still be times when it is wet, right?
--- "J. G. Kincade" <firstname.lastname@example.org> wrote:
> John is correct. My experience with telephone
> company buried cable is the
> same. Unless there is something besides air to
> physically consume the
> remaining space in the conduit (phone company cables
> are injected with a
> waterproofing gel substance under pressure during
> manufacture) moisture
> absolutely will build up inside. In my installation,
> my tower base is about
> 60' uphill from my shack. The difference in
> elevation is about two feet. I
> used 3" grey electrical conduit because I wanted to
> run several coax lines
> in it, with the first run to the tower base serving
> as a jumpoff point for a
> second run to the base of my groundmounted vertical.
> All I had to do was put
> a loose wad of fiberglass screen in each end (to
> keep out critters). The
> conduit has a natural slope to it, so standing water
> is not a problem. It is
> still "wet" inside, though, so using direct bury
> type coax for ANY conduit
> installation is something I'd recommend. My conduit
> is only buried about 6"
> deep, just enough to keep me from damaging anything
> with the tractor or the
> riding mower. I'm putting up a larger new tower soon
> a little further from
> the shack, and I think I'll go with John's idea of
> perforated 3" or 4"
> plastic drain pipe for that one, because the last
> 40' will be on level
> ground. The right size conduit to use is twice as
> large as you think you'll
> ever need. Otherwise, Murphy's law will prevail in
> the future, when you want
> to add a line for that new coax switch two years
> from now, or whatever. The
> difference in materials cost between 2" and 3", for
> instance, is minimal
> compared to the possible future aggravation of
> having a conduit that's too
> small for your needs.
> 73, Jerry W5KP
> > So the answer is to put the cable in a conduit of
> some sort--
> > typically plastic pipe, right? WRONG, wrong, and
> more wrong.
> > During daily temperature cycling, the pipe will
> pull in warm,
> > moist air and the moisture will condense out when
> the pipe
> > cools. Over time the moisture will build up
> inside the pipe
> > until the coaxial cable is guaranteed to be laying
> in water.
> > The worst possible situation for a pin-hole filled
> PVC jacket.
> > I have seen this EVERY time I have taken cables
> out of
> > PVC pipe that has been buried for some time--even
> in the
> > dry climate of Colorado.
> > The secret to burying cable (if you must) is to
> use a pipe
> > with drain holes. If you want a relatively large
> pipe then
> > use standard sewer drain pipe with holes every few
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