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Author Topic: grounds  (Read 592 times)
MIKEW
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Posts: 6




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« on: February 11, 2010, 09:16:40 PM »

I have been told that I need to drive 4 gound rods make them common and ground my equipment to them. they would be about ten feet from my equip. in the shack. will these serve as lightning protection also or only RF. ? and should I use braided wire or will solid suffice?
These rods are 10 ft long, and im in rocky ground..

thanks

Mike
KD0ISJ
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K9KJM
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Posts: 2415




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« Reply #1 on: February 11, 2010, 10:08:53 PM »

First question is, Who told you that, And what is the basic reason for the ground?

Ground "rods" do little to nothing for an "RF" ground. RF ground is obtained by running radial wires near the surface. (Ground rod interconnecting wires Could be part of such a radial plan)

Ground rods driven deep are for the lightning protection system, And it IS very important that all be bonded, or interconnected with your power, Telco, Cable TV etc grounds.  Ground rods should be spaced about twice the distance apart as the depth. (10 foot deep rods would be spaced about 20 feet apart.) IF you can only get them in, Say 5 feet, Then  just cut them in two and space them about 10 feet apart and have twice as many.

In a good lightning protection system, only 4 rods is simply a "start"

There was a pretty good series of three articles By Ron Block a few years ago in QST:

http://www.arrl.org/tis/info/pdf/0208053.pdf

If rock is real close to the surface, You can make homemade "Enhanced" grounds by doing stuff like getting some copper tube, Drilling it full of holes, Fill it with rocksalt, Backfilled with flyash or charcoal, And lots of other things.....
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K9KJM
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Posts: 2415




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« Reply #2 on: February 11, 2010, 10:13:31 PM »

And the statement that you need to ground your equipment to your ground system is not a real good one either. You want to ground the coax SHIELD where it enters the building, To your "Single Point Ground" panel, Which is where coax switches, Lightning arrestors are mounted is most important. Also, Your mast, Or tower would be connected to the ground system.  The object is to put any lightning strike to ground OUTDOORS before it gets to your equipment.

"Braid" is NOT a good product to use. Flat copper strap is one of the best. (.022 or so thick copper roof flashing, Available at home supply stores.)  If wire is used, #6 gauge is considered the lightest to use. Heavier is better.
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W8JI
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Posts: 9749


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« Reply #3 on: February 11, 2010, 10:37:06 PM »

I have been told that I need to drive 4 gound rods make them common and ground my equipment to them. they would be about ten feet from my equip. in the shack. will these serve as lightning protection also or only RF. ? and should I use braided wire or will solid suffice?
These rods are 10 ft long, and im in rocky ground..

thanks

Mike
KD0ISJ

Mike,

If you drive several ground rods in the ground and wire them to the radios and call it done, you will almost certainly greatly INCREASE the chances of lightning damage.

That is no way to do a ground system for RF or for lightning.

Try reading this:

http://www.w8ji.com/ground_systems.htm

Tom
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K6AER
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Posts: 4665




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« Reply #4 on: February 12, 2010, 08:17:02 AM »

An improperly installed ground system as Tom had mentioned, can cause more damage then no ground at all.

For instance, if you ground you radio and not bond and ground your AC panel with a AC surge protector, when a surge comes in via the AC line your radio will get fried when the surge travels through your radio to your newly installed grounds.

I wish for efficiency sake, E-Ham would just add a link to the Polyphaser site at the top of the main page.
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K0BG
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Posts: 10248


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« Reply #5 on: February 12, 2010, 09:58:55 AM »

Mike, while PolyPhaser does a creditable job, their solutions are only a chapter or two in the book. Personally, I like Tom's approach, and like him, I've suffered no damage even though my radios stay connected, 24/7/365. It is, after all, in the details.
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