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Re: [TowerTalk] Phillystran Tension Gage

To: towertalk@contesting.com
Subject: Re: [TowerTalk] Phillystran Tension Gage
From: Ken Alker <ka6ken@alker.net>
Date: Sun, 25 Jul 2021 13:04:06 -0700
List-post: <mailto:towertalk@contesting.com>
If my conclusions are correct, the chart appears to be based upon the breaking strength of a different type of wire than one would use for a tower. The chart appears to be based upon stainless steel cable (for sailboats) rather than zinc coated cable (for towers). The SS cable has a higher breaking strength, hence, using the Loos would mean one would over-tention the guys on a tower if using the % scale, rather than the LBS scale.

--On Sunday, July 25, 2021 3:49 PM -0400 john@kk9a.com wrote:

Why are you concerned with the Loos gauge's breaking strength chart?  I
just use the table to set the guy wires to the recommended tension
(usually 10% of its breaking strength).

John KK9A



Ken Alker ka6ken wrote:

I'm new to this, but did a lot of research and found that the Loos PT2
appears to be calibrated for wire with a breaking strength of 4545-5000
lbs, while the Rohn 3/16EHS500 wire has a breaking strength of 3990 lbs.
I  assume, based on specs on various types of wire rope found at
<http://www.wcwr.com/catalog/webcat.pdf>, that the Loos PT2 is calibrated
more for 1x19 Stainless Steel type 304 wire rope used for sailboat
rigging  (4700 lbs) rather than zinc coated 3/16EHS500 (3990 lbs).  Here
is my math  based upon the chart found on the Loos gauge (from the web
site quoted by  Tim, below):

 LBS   %  LBS/%
----  --  -----
 240   5  4800
 300   6  5000
 420   9  4666
 500  11  4545
 640  14  4571
 840  18  4666
1030  22  4681
1240  26  4769

In conclusion, perhaps one should pay more attention to the "LBS TENSION"
portion of the Loos chart than the "% BREAK STRENGTH" if using the Loos
for  3/16" EHS (assuming it deflects in the same way that the sailboat
wire rope  deflects), or one may overtension their guys.  (Although,
perhaps the error  when tensioning to 10% of breaking strength when
tensioning to 400lbs, or  600lbs in the case of Phillstran, isn't big
enough to worry about?)

Even then, however, I'm very curious as to why the Loos numbers are all
over the map (4545-5000) rather than consistent at one breaking strength;
it is not just rounding error since their "LBS TENSION" appears to be
+-10  lbs.

Ken, KA6KEN

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