[TowerTalk] Loos PT-3

k7lxc at aol.com k7lxc at aol.com
Wed Jan 17 14:10:58 EST 2018

>  Hello-?? Just a quick question -- I?was looking at a?Loos PT-3 gauge and have been studying the specs. It was of interest?to read that the gauge is intended to be used primarily?for 19 strand?SS cables such as on sailboats, and that calibration on cables of other construction will be a little different.?? My question is does anyone have knowledge or info on how accurate the gauge is on the 7 strand EHS guy wire we all use, is it off very much as compared to the intended cables to be measured?
    Yes, the Loos gauges were designed with 7/19 SS cables. Don, K4KYV, tested a Loos PT-2 and measured it against a Dillon tension meter. Here is the original post:
Below is my conversion chart for my 110' Rohn 555 tower, which uses
HPTG67001 Phillystran guys with 1/4" EHS leaders from the guy anchors to a
level that's about 15' off the ground (to protect against vandalism, brush
fires, etc.) The guy lengths vary with height and direction because my tower
is on a steep hill, but the EHS portions are 29' on two sides and 37.5' on
the remaining (downhill) side, or roughly 20%-30% of each guy length.

I calibrated the Loos gauge against a Dillon dynamometer attached in line
with the EHS portion of the actual guys using a Klein grip and come-along.
Loos       Loos      Dillon
Reading    Chart     Reading

  26       450        300
  27       500        400
  30       660        450
  31       720        500
  32       780        600
  33       840        660
  34       900        700
  35      1000        765
  36      1100        850
  37      1200       1000

-----Original Message-----
From: Donald Chester [mailto:k4kyv at hotmail.com] 
Sent: Saturday, October 22, 2016 12:29 PM
To: towertalk at contesting.com
Subject: Re: [TowerTalk] Guy Tensioning

> 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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