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Old 13-Dec-2010, 2:30 PM   #1
jp2code
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Kevlar Guy Wire?

I've got a 10-ft pole that my antenna mounts to, and it shakes just a bit in strong winds causing pixelation on the TV inside.

Steel guy wire is expensive, or more expensive than Kevlar thread which is supposed to be very strong stuff!

How do you think Kevlar thread would work for guy wires? I only need 2 support wires, and each of them will be less than 20-ft in length.
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Old 13-Dec-2010, 10:04 PM   #2
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Kevlar can be as strong or stronger (per unit weight) than steel, but the down side is that it has poor UV resistance. I wouldn't recommended it for outdoor applications because you'd have to replace it regularly.
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Old 13-Dec-2010, 10:33 PM   #3
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Channel Master item number 3084 (100 feet of 20 gauge 6-strand galvanized steel wire) is available from their web site for $12.99 (link), and they have a free shipping promotion going right now. This kind of wire is only good for holding 100 pounds or so, but that should be sufficient for mast stabilization.

It's probably a lot cheaper than the typical galvanized or stainless steel "rope" you see at local hardware stores that can hold 700+ pounds and costs upwards of $1 per foot. That stuff will work too, but it's overkill for this kind of application.
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Old 14-Dec-2010, 1:46 AM   #4
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Good info. Thanks.
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Old 14-Dec-2010, 7:28 PM   #5
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How do you think Kevlar thread would work for guy wires? I only need 2 support wires, and each of them will be less than 20-ft in length.
Kevlar with a plastic jacket to resist UV rays is sold as Phillystran. It's more expensive than metal. You'd use it when steel guy wire will change the performance of the antenna system.

A cheaper alternative that's OK with UV is black dacron rope. http://www.hamcity.com/store/pc/view...idCategory=392
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Old 14-Dec-2010, 8:31 PM   #6
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So, whether I use Kevlar, steel or Dacron guy wire, how should I tie off this stuff?

I hear Kevlar will snap when it is bent.

Steel guy wire - does that twist on itself like the ends of a wire coat hanger or would I use electrical type of crimp connections?

I'm not sure what type of special material Dacron Rope is made of, but would it require anything special?
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Old 15-Dec-2010, 9:49 AM   #7
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So, whether I use Kevlar, steel or Dacron guy wire, how should I tie off this stuff?
I typically use a figure-eight loop knot to attach the line to the various end-points (ring anchors, guy-wire ring, etc.). For tying into closed rings, you need to first put a loose figure eight knot in the line, then pass the loose end of the line through the ring, and finally follow through the first figure eight knot backwards with the loose end (a video might help). After you've learned this knot once, it's relatively easy to remember, it's very secure (never comes undone on its own and never slips), and it's a type of knot that doesn't put very sharp kinks in the line. There are other great knots that will work and might not require as much slack as the figure-eight loop, but I find this knot to be one of the easier ones to remember.

In most circumstances, you will need turnbuckles to apply the final tension tightening on the lines.



Quote:
I hear Kevlar will snap when it is bent.
Kevlar does lose strength when folded or bent, but for mast stabilization, you're only talking about forces that are typically well under 100 pounds. Kevlar inside of a plastic sleeve will reduce the sharpness of the kinks, and a smart choice in knots will minimize the damage too. Hopefully, your mast will not be subject to stress levels that will test these limits.



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Steel guy wire - does that twist on itself like the ends of a wire coat hanger or would I use electrical type of crimp connections?
Wire twisting will not work. It will loosen too easily and will not hold the required tension.

Crimp on fasteners work well, but then you need to buy the crimp fittings and crimp tool to do the job.

The figure-eight (or any other suitable knot) method also works, and does not require any extra tooling, however, it does require more slack at each end to allow you to tie the knot. If this kind of knot is new to you, then you might want to practice a few times in your living room until you've memorized it and also become better at judging how much slack you need at each end to complete the knot.
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Old 28-Dec-2010, 1:20 AM   #8
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So I went with the black dacron rope.

It got here, and guess what? This is the same stuff sold at Home Depot under the name Nylon Clothes Line rope. Same price, with no shipping fees.

Just FYI for the group.
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Old 28-Dec-2010, 9:24 AM   #9
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So I went with the black dacron rope.

It got here, and guess what? This is the same stuff sold at Home Depot under the name Nylon Clothes Line rope. Same price, with no shipping fees.

Just FYI for the group.
They may look similar, but Nylon and Dacron are different synthetic fabrics. Nylon stretches more than Dacron.
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Old 27-Mar-2011, 2:15 PM   #10
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OK, so I've had this Dacron Rope installed for 3 months.

So far, I've had to go back up on the roof and tighten it down twice (2 times) because it keeps stretching.

Crap stuff. I would not recommend that over a steel wire.
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