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Re: [TowerTalk] Guy Tensioning

To: "towertalk@contesting.com" <towertalk@contesting.com>
Subject: Re: [TowerTalk] Guy Tensioning
From: Donald Chester <k4kyv@hotmail.com>
Date: Sat, 22 Oct 2016 16:28:38 +0000
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
> The Loos gage from Champion is easy to use to adjust the tension. In my case 
> 10 % of the 4,000 lb rated cable and phillystran. 

> Fred KC5YN

I use the better grade Loos gage for my 3/16" guys.  Well worth the cost.

The calibration chart that comes with the instrument is correct only for the 
19-strand wire rope it was designed for, which is what they use for sailboat 
rigging.  The stiffness of the cable  determines the reading as much as does 
the tension.  The chart that comes with the gauge is WAY off and totally 
useless for EHS guy cable.  I'm sure it would be just as far off, if not more 
so, with phillystran.

I made up a conversion chart by purchasing a few feet of the exact type of 
19-strand rope the gauge was designed for.  I attached the wire rope to a piece 
of 3/16 EHS guy cable, using a small strain insulator and a couple of cable 
clamps, and strung the whole thing between two trees, with a come-along and a 
turnbuckle at one end. I tightened the cable in increments with the come-along 
and fine-adjusted the tension reading with the turnbuckle, at each step 
recording the tension of the 19-strand rope according to the Loos chart,  then 
moved the Loos to the EHS and again noted that reading, and thus made up my 
chart.  With the two pieces tied together, they both have the same tension, so 
the tension reading on the wire rope has to  be the same as the tension on the 
EHS, thus allowing me to make up an accurate chart for 3/16 EHS.  That same 
procedure would work equally well with phillystran; I would make up a separate 
chart for each.

Before acquiring the Loos I had always tensioned my  guys by feel and by 
eyeballing the sag.  I was amazed how poorly that had worked and how 
non-uniform the tension was between different levels of guys.

The only time I ever set the tension all the way to 10% of breaking strength is 
in winter when the temperature is in the 20s or less.  You might not believe 
how much the ambient temperature affects guy tension.  If they are tensioned to 
10% on a warm summer day, the entire guy system will be grossly over-tensioned 
when the temperature drops to single digits.  I think of 10% as the maximum 
tension to be reached with temperature variations, not as the normal operating 
tension.  Since my 127' of Rohn 25G is used only as a vertical radiator and to 
hold up a single dipole, there is not a lot of wind loading, and I don't think 
the  guy wire tension is all that  critical.

Don k4kyv
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