On Sat, 18 Oct 2003 21:18:02 GMT, helmsman
wrote:

yea right wrote:

I would like to bury my coax for a distance of about 20ft. The location
consist of 6" of crushed decorative rocks over the top of very rocky soil.
SNIP
Anybody have any suggestions?

I can't find the original post, and going to Google to get it would be
starting another thread, soooo,,,, I'm just going to insert here.

The answer is one of those , "It all depends" on what you want for
reliability. It also depends on whether you will have any connections
underground. OTOH, connections underground are little different than
connections above ground. They should be treated the same.

Crushed rock and very rocky soil are about the worst location for
burying coax. PVC conduit is *cheap*, or at least relatively
inexpensive, particularly if you are only going to have one run of
coax. I have 7 coax cables 3 TV RG-6 cables, two rotor cables, a
power cable tot he 2-meter preamp and some other assorted *stuff* run
through mine. I use a 75 foot run of 4 inch PVC to a junction box on
the tower.. http://www.rogerhalstead.com/cablebox.htm

Go to the hardware and get a tube of silicon sealant and seal the
ends, if you don't think that's enough seal one end and shoot nitrogen
gas in the hose to displace the air and then seal it quickly.

A point or two here...If you want to force N2 through the coax you
need *both* ends open. However it *will* breathe as pressure changes
with temperature. Do NOT seal both ends of a coax run. Do the best
possible job up on top and leave the end in the house unsealed.
IF you seal both ends the pressure will eventually equalize. Then with
each temperature change it will either pressurize, or draw a vacuum.
This will eventually draw in moisture. I use heat shrink tubing on
top of the tower and fill the connectors with DC-4 silicon grease.
This works at least up through 440 and for all legal amateur power
levels.

SPLICES: The easiest and surest way to seal a splice from the weather
is to go to your local electrical supply house and purchase a length
of 3M (TM) 0800 IMCSN .80/.22 20/5/6mm flooded heat shrink tube for
RG-8 size cables. The stuff is *about* $10 for a 40 inch length. It
is coated inside with something akin to hot melt glue. It not only
does a tremendous job of weatherproofing, but adds mechanical strength
as well. Don't be cheap and expect to reuse the connectors although
you might get lucky and be able to do so.

"Unshrunk" the tubing will easily fit *over* a PL250, or N connector.
That .8 indicates the inside diameter prior to shrinking. It will
shrink all the way to 0.22 inches. Make your splice using either a
male to female connection, or two males with a barrel connector in
between. Slip a length of the heat shrink tubing long enough cover
the entire splice and extend at least 1 1/2 to 2 inches beyond the
connectors onto the coax jacket.
When applying heat to shrink the tube onto the splice be sure and
start in the middle and work outward. IF you start on the ends it will
look like a snake that just swallowed a very big frog by the time you
get any where near the center:-))
This method does a far neater and better job than coax seal and tape.
Less mess, adds strength, and is as waterproof as you are going to
get. It has the drawback of requiring a heat gun to shrink the tubing
(which sometimes means a very long extension cord, but I use them on
top of a 97 foot tower), nor will it fill a hole where coax passes
through like coax seal.

Roger Halstead (K8RI EN73 & ARRL Life Member)
www.rogerhalstead.com
N833R World's oldest Debonair? (S# CD-2)

Have a good day:')
.
Don't buy goods made in France or Germany and vacation somewhere else!