Don,
Finally glad to see that someone else is a bit more 'clued in' on
tensioning guys using a Loos gauge.
So often in the past, I've seen people recommend them, and others, go on
and on about how great they are, with NO ONE mentioning that they are
not intended for EHS guy wire, which is normally what is used towers.
You can surely get EQUAL tension, but what is that tension?
I have often thought of doing just what you have done, which is a 'must'
if you want to use a Loos gauge with confidence. My problem is that I
didn't have any sort of strain gauge to throw into the mix.
73 de Steve, NR4M
On 10/22/2016 12:28, Donald Chester wrote:
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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73 de Steve, NR4M
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