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Author Topic: How many lightning arrestors are needed?  (Read 1378 times)
KE0Q
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Posts: 19




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« on: February 20, 2013, 10:16:14 AM »

I'll be putting up a 43 ft Zero-Five Vertical as soon as the snow melts in Minnesota.  I'm planning on using one lightning arrestor where the coax enters the shack and and one at the base of the vertical.  Will using an additional arrestor at the base of the antenna provide a little more protection or is it overkill?  Tim - ke0q Huh
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AA4PB
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Posts: 12897




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« Reply #1 on: February 20, 2013, 11:02:33 AM »

Just before it enters the shack is the important location. The arestors need a proper single-point ground to be effective.
You can find some good information on the PolyPhaser web site.
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K4PP
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Posts: 64




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« Reply #2 on: February 20, 2013, 06:43:38 PM »

I also put in a ground rod at the base of my vertical and mounted a lightning arrestor to it. I have been meaning to put one up at the entry to the house (quite a run from the antenna) but just haven't done it yet. I went through the same thing as it seems like the at the antenna was the logical place, but then there is the coax run up to the house, the point beyond which you want protected. I finally decided two wouldn't hurt and would be a little more protection. You still need to bond all the ground rods and back to the AC service ground.

K4PP
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WB6BYU
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Posts: 13341




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« Reply #3 on: February 20, 2013, 08:43:25 PM »

Remember that a lightning arrestor is designed to break down at high
voltage.  If you are running a tuner in the shack, then there can be
high RF voltage at the antenna feedpoint, and the arrestor will limit
the power that you can run on the antenna.
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AD4U
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Posts: 2173




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« Reply #4 on: February 21, 2013, 05:29:35 AM »

And one more thing..............Even the best and most expensive lighting arrestor is no better than the ground it is connected to.  Do not skimp here.

Dick  AD4U
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W5LZ
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Posts: 477




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« Reply #5 on: February 21, 2013, 12:18:48 PM »

If it's done right, a single arrester should do fine.  That 'done right' thingy means the whole system, not just part of it.  If the whole system isn't at least -close- to right then it won't matter if you have three dozen arresters.
 - Paul
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AA4PB
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Posts: 12897




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« Reply #6 on: February 21, 2013, 12:28:43 PM »

and if you get a direct hit to the antenna it probably won't matter if you have 100 arrestors - they'll all be a pile of melted aluminum. The most important thing is a single point ground just before the coax enters the house in order to keep the majority of the current flow outside of the house. Lightning arrestors only handle fairly minor surges and probably aren't even needed if your antenna center conductor is DC grounded.

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