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[TowerTalk] Grounds

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Subject: [TowerTalk] Grounds
From: (Tom Rauch)
Date: Thu, 17 Jun 1999 10:06:47 -0400
>      the basement you can drop the cord/plug onto the cement floor. So,
>      now you have reduced the potential PATH by having a half inch gap
>      between the plug prong and the grounded(?) cement floor. Will it
> jump 

That's a gross over simplification.

The power and voltage divides by impedance ratios in many paths. 
The above over simplification, while it sounds convincing, paints a 
totally incorrect view of the problem because it assumes the ONLY 
path is the path through the rig. 

Adding a series one inch air gap results in a tremendous increase 
in protection, because the impedance of that path greatly 
increases compared to other paths (such as the one through the 
ground system outside the house).     

>         OK,  so you put the cord up on the table,  but in the meantime you
>      had put the rotator control box on the wooden table, and it's
> plugged 
>      in. How much distance between that control box and the rig? Not near
>      as far as between the cloud and your antenna, right?  

Same thing. Another gross over simplification of the actual system. 
The path through air from the cloud to earth is the ONLY path 
available, the paths in the system on earth are many. 

The description assumes there are no other grounds or paths. I 
would hope that isn't true by the time the wall of the house is 
reached, or you are in deep doo-doo.

The real trick is to insure a many times BETTER path occurs 
OUTSIDE the shack and to unhook the leads coming into the 
shack.  Then what you do inside the shack doesn't make a great 
difference. You don't want loops through the equipment, but if you 
are shortsighted enough to do the grounding in the shack by 
moving plugs you are very likely in big-time trouble.

73, Tom W8JI

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