Date: Tue, 18 Jun 2013 23:37:35 -0400
From: "Mark Robinson" <markrob@mindspring.com>
To: "K0DAN" <k0dan@comcast.net>, "Randy" <randy@verizon.net>
Cc: towertalk@contesting.com
Subject: Re: [TowerTalk] Screw Anchor Experience
There was an article about this in QST a while back. I followed the article
and installed Magnesium sacrificial anodes to protect my buried guy anchors
from corrosion.
Mark N1UK
## why mess with screw in anchors ? Only power company’s + telco’s use em.
Even then
they use eggs in the EHS guys. A 40’ tall utlility pole is already 6 feet
into the ground. No
anodes used.
## The rohn type rod anchors are in contact with the soil, where it is
trenched, so that portion
of the rod needs to be coated with roofing tar pitch. Those GAC series anchor
rods involve
excavating a huge hole, that is then trenched. The concrete slab needs to be
poured, then the
entire mess is bakfilled with dirt.
## A better way is to use elevated anchors. Six to ten inch diam steel pipe is
used. Weld a
steel plate onto the bottom of the pipe. Then weld 3-4 rocket fins onto the
base. Pour
a layer of crushed gravel onto the base of the hole, then drop in the steel
tube. A .375 inch
to .5 inch thick steel rectangular plate, typ 4-6 inchs wide x 12-14 inchs
tall is welded to the
side of the steel pipe. Typ 4-5 feet above ground level. Fill the hole
with re-enforced
concrete and rebar. And don’t forget to fill the INSIDES of the steel pipe
with concrete as well !!
## I designed the above guy anchor bases for a buddy with a 190 foot tall
rotating tower + 14
yagis. He used 10 inch diam steel pipe, sched 40. Then had it all hot dip
galvanized..after
all the welding was done. It uses a fair amount of concrete for the 3 x
holes. Flip side is
it’s a fast install vs installing a slab of concrete at the bottom of a
hole, trenching the hole, and
using anchor rods, then backfilling. .375 inch fiberglass guy rod used for the
12 x guys...with the
bottom 20 feet using EHS.
## If EHS used for guys...along with egg insulators, dunno if the last
little bit of each guy
needs to be grounded or not. The base of the tower is grounded, and the eggs
have insulated
the EHS steel guy cable, so grounding the last bit of guy wire is not really
doing anything.
later... Jim VE7RF
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