An ever recurring topic......4 way guying!
Usually it is for the same reasons, real estate space is at a premium.
One possible solution to a space problem is:
Have you thought about rotating your anchor points by 60 degrees? If
rotating them by 60 degrees makes your landing points land within your
yard's boundaries I would encourage you to do the following:
Instead of guy 1 pulling out on leg 1 away from the tower, pass it through
the tower so that guy one passes through the center of the tower and then
exits between legs 2 and 3. You need to use care to make sure you are not
riding on the cross braces when doing this.....I have seen this technique
used many times. The only hard part is the top set of guys - if you are
guying at the top of the tower this is impossible due to the mast being at
the heart of the towers cross section. Alternative solutions for the top
include fabricating a framework like Rohn uses for dish mount tops where
the guys end up coming off at right angle to the face.....or possibly
having six short lengths of guy wire, two for each face meeting several
feet out from the tower, and those forming the point for the top of the top
guy wire's run.
4-Way?
The reason to shy away from 4 way guying is really pretty straightforward.
The ideal tower structure from a mechanical engineering view would be
cylindrical one where lateral forces would be equally distributed all over
by virtue of it being a cylinder, just like the tubular boom of your yagi
does...do the impracticality of a tower being cylindrical you end up with
the smallest number of sides possible to create something with a
perimeter...the triangle.
The typical tower section has three equal sides and three legs which become
the focus of the forces being put on the tower. If you try and guy four
ways the forces the guys will be placing on the welds, etc in the tower are
not ones which the design, an equilateral triangle, anticipates.
The smoothest way to convert this combination of forces for four points
from three discreet "focuses" of force in my opinion would be to attach a
"ring" on the three legs of the tower, and that ring would have four
equally spaced guy attachment points.
This is a bit of a purist view, but considering the tower is designed with
the anticipation of THREE guy points, simply putting two on one leg, and
changing the vectors on the others is asking it to do a REAL lot of things
it was never intended to do.
Try the math for rotating your guy points 60 degrees....a lot of times guys
have to do this when they extend their towers and find that the necessary
distance out from the base is no longer on home turf.
....from a mechanical engineering dropout:
73,
Jim, K4OJ
Florida Contest Group - visit our website at:
http://www.4w.com/deemer/fcg.htm
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website@:
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