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Re: [TowerTalk] Station Ground

To: <>, "Frank Donovan" <>
Subject: Re: [TowerTalk] Station Ground
From: "Michael Tope" <>
Date: Fri, 14 Jan 2005 21:33:01 -0800
List-post: <>
> With a common buss bar you have ground loops between pieces of 
> equipment. If a surge, lightning etc. should get through to one piece of 
> equipment it will hopefully exit via the ground to the ground window.
> If there is a common buss bar the surge can enter another piece of 
> equipment and go through it via the ground connection on it's way to 
> ground. The ground lead from the buss bar will always have some 
> impedance so it will be somewhat above ground with a surge.
> With individual ground leads to the ground window there is no loop 
> through other equipment. Not always doable but it is the proper way.
> 73
> Gary  K4FMX


That might be true if each piece of equipment in the shack 
was totally isolated from every other piece of equipment. In 
reality there are all kinds of incidental chassis connection 
between gear. Gear that is on a common 12V supply, gear 
that shares a coax shield connection, etc. There is also the 
green third wire in the AC supply line from each piece of
gear to consider. If you run a wire from the chassis of each 
piece of gear to your single point grounding window, you are 
still going to have all those other connections woven between 
gear. Some of those connections will be solid with large 
conductors making the incidental connection and some will 
be puny little RCA cables that incidental sneak path
connection. The buss bar concept gives you a hard low 
impedance connection shorted across all those various 
incidental connections. 

The real key to the single point ground concept is that your
trying to keep all the conductors entering the shack that
could be carrying a surge at the same potential. If that is 
the case, the connection between the panel and the equipment
is not so critical. The main thing is that you don't want a 
secondary path from the equipment to ground that doesn't
pass through the SPG window. 

73 de Mike, W4EF............................................. 


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