[TowerTalk] "Magic" length from tower to first insulator
Jim Thomson
jim.thom at telus.net
Thu Mar 17 13:27:24 EDT 2016
Date: Thu, 17 Mar 2016 10:21:32 -0600
From: mntsdad53 <mntsdad53 at yahoo.com>
To: "john at kk9a.com" <john at kk9a.com>
Cc: towertalk at contesting.com
Subject: Re: [TowerTalk] "Magic" length from tower to first insulator
Just planning installation of my first ever towers so not much experience here. What is the reason for the "last ten feet" utilizing EHS instead of Phillystran?
Don Shelton, N0KGU
## You can cut phillystran with a knife....and burn it in half with a bic lighter.
A 10 yr old kid could easily bring it down.
## on another note, the magic length from tower to 1st insulator will be the
distance of 2 pre-forms back to back...with a couple of inches between em, and a
short length of ehs, like 3 feet..with a pre-form on each end.
## I used I think 38-39-40 ft for the spacing between 1st and 2nd insulators on my guyed tower,
back in 1981. But the top 20 feet of tower was not guyed. No big deal since it was 30 inches across.
Just a single hb 20m yagi at very top. 76 ft tower....guyed at 36 ft and 56 ft. 20 ft sections..with
bottom 4 ft in a block of concrete. 1/4 ehs used.
## 3/8 fiberglass rod will also work instead of ehs. But I dunno if the grips are still available.
Several towers use 3/8 rod..and it works very well. Philly works..and so does a free standing
tower. Depending on height, by the time you price out philly, and all that goes with it, plus
3 x guy anchors, and 6-10 inch OD steel tubes sunk into concrete to make up the guy anchor
assy... in some cases you may as well install a free standing tower like the AN wireless variety
or the Trylon super Titan series. Then no guys to mess with, and easy to install the various
ants.
Jim VE7RF
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