Dave:
Actual experience in short guy wire distances... from my old QTH in Central
Illinois... I had 100' of Rohn 25G with a 5 el 20m beam (40')boom and a
6 el 15m above that. the two guy wire were out only 45', the other at 60'.
This tower was up for 3 years in some VERY heavy ice storms, but held up
okay. Now I did have them guyed 4 times (25,50,75, 100;) with the 1/4 EHS
with some large concrete pads, but it worked very well... All guy wires went
to single guy anchors...
for what it's worth..
73 de Mike/ N7MB
At 04:42 PM 5/27/97 -0400, David Clemons wrote:
>Hi,
>
> I have a question concerning guy wire anchor placement. I have
>two towers (one is 83 feet of Rohn 25 with a Hygain 155BA and 105BA, the
>other is 99 feet of Rohn 45 with Cushcraft 204-CD and 402-CD.) A recent
>edition of the ARRL handbook says that the anchor distance should be
>between 60% and 80% of the tower height. I have two anchors on each leg,
>with the lower two sets of guys on the inside anchor and the highest guy
>alone on the outside anchor.
>
> Now the problem - the 13 acres of property behind me was bought
>last year and the new owners are putting up horse corrals for their
>boarding/training business. We recently discovered that four of my guy
>anchors (both anchors on one leg of each tower) are actually on their
>property. They have been nice enough to tell me it's ok, but two of them
>actually fall inside one of the corrals and I think it best to get them
>out of there. I am not going to move the towers, so that means I have to
>put the anchors closer (the outer ones by 12 feet or so) and also
>probably shorten the towers somewhat.
>
> The underlying question really is "how much can I cheat on the
>angle of the guy wires?". Now there are those among you who will
>correctly tell me that any cheating is dangerous, and I understand that
>concept. However, I am also aware that there is a different amount of
>danger associated with the anchor at 59% of the tower height than at 39%
>or 29%. Also, my use of two anchors takes some strain off the anchor for
>the top guys - thus making the issue of the strain on the wire and tower
>legs more likely to be the critical problem. The guy wire is 1/4 EHS,
>which I believe is rated for 6600 pounds. The wires are broken up with
>insulators, and some of the wires are fastened with deadends while other
>connections are made using 3 cable clamps on each side. (If it mattered,
>I could replace all cable clamps with deadends.)
>
> Does anyone have any experience or idea of the reliability of an
>installation with the top anchor at 50% of the tower height? How about
>as little as 40% (about 68% angle to the ground)?
>
>73, Dave Clemons K1VUT
>
>
>
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>
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