Mike:
I'm planning for a self-supporting tower in the back yard at my QTH.
I debated the same things: slotted or solid conduit; DB jacket or not;
corrugated or smooth; gold or silver (just kidding.) I think I'll use solid
3" PVC to make it easy to add and/or replace coax. It's very wet here in MD
suburbs of DC and the slotted pipe will have water in it more often than
not. But I'm going to incorporate the following feature: a sump at the low
point(s) along the route. We used a similar design in underground
transformer vaults in the power company (PP&L) when I worked for them.
Here's my plan.
The cable route will be across my back yard and on to the tower
location about two feet lower in elevation. Total length about 60-70 feet.
I'll use a trencher to put the pipe down two feet below grade, with a slope
towards the tower. At at least one low spot, probably within a foot or two
of the tower base, I'll drill a hole with a fence post digger in the trench
and fill the hole almost to the bottom of the trench with large gravel, a'
la Rohn tower base. In the conduit run just above this hole I'll install a
PVC T fitting. The horizontal ends will splice into the conduit, and the
vertical T will (hopefully) empty any water into the hole where it will take
its time percolating into the earth. I'll also put a large gauge mesh
screen over the opening in the T to keep out large critters (we have plenty
of moles here in DC; many are actually NOT working for the government!)
I think the cost for this approach will be twice the cost of corrugated
pipe alone, but I'll be able to add/change/remove coax easily (no
corrugations to snag the pull line knot), provide more-robust protection for
the cable and keep it relatively dry.
BOTTOM LINE: I'd go down two feet (especially in PA) and use smooth
PVC (tougher than corrugated stuff), but also add a sump to collect and
disperse any accumulated water.
GL es 73 de
Gene Smar AD3F
-----Original Message-----
From: Michael Wacker <mwacker@epix.net>
To: towertalk@contesting.com <towertalk@contesting.com>
To: <towertalk@contesting.com>
Date: Friday, May 04, 2001 3:39 PM
Subject: [TowerTalk] Coax
>When putting coax in PVC pipe for underground burial, should I get the
>PVC pipe with or without the holes? How deep should I go? QTH is
>Pennsylvania.
>
>Mike N3HR
>
>
>List Sponsor: ChampionRadio.com - Trylon self-supporting towers,
>safety equipment, rigging gear, LOOS tension guages & more!
>http://www.championradio.com
>
>-----
>FAQ on WWW: http://www.contesting.com/FAQ/towertalk
>Submissions: towertalk@contesting.com
>Administrative requests: towertalk-REQUEST@contesting.com
>Problems: owner-towertalk@contesting.com
>
List Sponsor: ChampionRadio.com - Trylon self-supporting towers,
safety equipment, rigging gear, LOOS tension guages & more!
http://www.championradio.com
-----
FAQ on WWW: http://www.contesting.com/FAQ/towertalk
Submissions: towertalk@contesting.com
Administrative requests: towertalk-REQUEST@contesting.com
Problems: owner-towertalk@contesting.com
|