Date: Mon, 28 Aug 2017 08:41:34 -0400
From: Dick's <rcblumen@centurylink.net>
To: Tom Hellem <tom.hellem@gmail.com>
Cc: towertalk@contesting.com
Subject: Re: [TowerTalk] Direct Burial Of Coax (Was "A Dumb Question")
<I stand corrected. I think you folks are correct. My idea of burying coax in
sand and protecting it with plastic trim boards is not as good as laying the
coax in perforated pvc pipes that have drain holes over pea gravel. Both are as
effective in the short run, but <with the pipe you can always replace the coax
or add another line if you pre-ran a string or rope with the coax.
<Dick, K0CAT
## The issue with the PVC pipe with the aprx .375 holes down each side
is..... for ham use, you have to orient the holes, so they are facing up..and
down. In normal drain tile usage, the holes are oriented so they are on each
side, to allow water in..and drain away. For ham use, with holes at the top
and bottom of the pvc.... sure if water gets in, it will drain though the
bottom holes, but it will also allow water to ingress, via the top holes. A
better method would be to use pvc with no holes at all, then drill out
a single row of holes...and orient those holes, so they face straight down,
towards the bottom. Then at least you get to decide how many holes you want,
and what spacing you want, and hole diam. Then dig your trench, fill partly
with sand, put the pvc pipe in, then cover up with more sand, or what ever you
want. You could always add an above ground T or Y....and also plug the hole
+ cables with duct seal at one end.... and leave the far end open. Then stuff
either compressed air or the blow end of a shop vac at the T or Y. Then
leave it on for 40-60 mins. You would dry it out pretty quickly. I have a
unit that is made to dry out wet vehicles. Stupid high pressure vs a shop
vac..and has heat too. Bought it at the local harly davidson dealer. Called
an Airforce blaster.. made in NY...and built like a tank. You could also put
a nitrogen bottle on one end, the humidity is 0 % with nitrogen.
## Cables sitting in water, have to be designed to sit in water 27 /7. Once
water gets into the pvc, it stays put.... and just accumulates, gets worse.
If the pvc is only less than 1 foot below ground, the standing water inside
the pvc will freeze in winter, compounding issues. Folks who have in ground
sprinkler systems know this..which is why in the winter, they are shut down
for the season, and standing water is blown out with compressed air.
## Drilling out a single row of holes by hand, imo, has a lot going for it,
then sit the pvc in sand filled trough, then cover it up with what ever you
want. Any water just drains into the sand below. Cables are not sitting in
standing water. The shop vac procedure can be done once per year during the
hot summer months, with far end opened off, to completely dry it out....which
may nor be required at all... but easy to do.
Jim VE7RF
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