Chain link fence

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mbrockm
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Location: Shenandoah, Iowa

Chain link fence

Post by mbrockm » Tue Jun 13, 2017 9:12 am

We have always had wooden fences around our towers. Need to replace around our center fence. Thinking of going to chain link, less expensive and durable. Question I have is how often do I need to ground the fence. I was thinking the 4 corners and 4 sides would be adequate.
Mark Brockmeyer
KMA Engineering

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Deep Thought
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Re: Chain link fence

Post by Deep Thought » Tue Jun 13, 2017 11:42 am

Depending on the frequency involved, the tower height and how close the fence is to the tower you may need to ground it more often, but the corners and midway between them is a good start. Definitely make sure that there is a horizontal wire run through the entire fence and that it is grounded to the tower ground system. You might also want to make sure that there is a wire connecting the gate to the rest of the fence unless you like getting RF burns from the lock. :shock:

If the tower is over 90° tall and/or you are on the upper end of the band the tower impedance may shift a bit.
Mark Mueller • Mueller Broadcast Design • La Grange, IL • http://www.muellerbroadcastdesign.com

rfn
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Re: Chain link fence

Post by rfn » Tue Jun 13, 2017 9:15 pm

Look into alternative fencing. There are new materials, all of which are non-conductive. If you'd like a wooden look, Trex or similar product works well. There are also plastic material that have the durability of and look like chain-link and might actually be tougher to cut than actual steel. Also, if you run a continuous wire through steel mesh you're looking for trouble with dis-similar metals in contact and the effects of oxidation on the two materials. Not so many years ago I fabricated a fence with wooden posts connected by horiontal 2x4 pressure treated lumber. One horizontal low; the other high. Drilled through at 4 (or so) inch intervals with plastic pipe threaded through. Then, on the inside, one BRASS screw run into each pipe so they could not just be lifted out. I did that because of drifting snow that, previously, had made it possible to walk right over a 10-foot tall fence. With the round cross-section and slightly wider spacing the snow mostly just blew through.

https://www.fybush.com/Tower%20Site/030 ... -close.jpg

If you go to the link you'll see the posts are 20-footers. Each is drilled and woven with yellow polypropylene rope so as to form at least a visual barrier in case the snow tops the fence. The call letters will tell you more about where that was necessary.

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Deep Thought
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Re: Chain link fence

Post by Deep Thought » Tue Jun 13, 2017 11:18 pm

rfn wrote:
Tue Jun 13, 2017 9:15 pm
Also, if you run a continuous wire through steel mesh you're looking for trouble with dis-similar metals in contact and the effects of oxidation on the two materials.
That's why you use the same galvanized wire the fence companies use to secure the top and bottom parts of the chain link. It may be there already.
Mark Mueller • Mueller Broadcast Design • La Grange, IL • http://www.muellerbroadcastdesign.com

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Jim Sofonia
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Re: Chain link fence

Post by Jim Sofonia » Wed Jun 14, 2017 7:59 am

We used sizable pre-fab dog pens at the base of our towers. Easy and cost effective. Tied into the ground system at four points. Never had any problems. You can always add extra grounding later as needed.

mbrockm
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Location: Shenandoah, Iowa

Re: Chain link fence

Post by mbrockm » Wed Jun 14, 2017 8:26 am

Tower 480' used for Non DA and DA on 960. Fence is 25 feet from tower. Looked into vinyl which would look good but about 2K more in price then chain link. As most of us are, I am looking for least expensive.
Mark Brockmeyer
KMA Engineering

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