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Re: [TowerTalk] Station Ground

To: Tom Rauch <w8ji@contesting.com>
Subject: Re: [TowerTalk] Station Ground
From: Gary Schafer <garyschafer@comcast.net>
Reply-to: garyschafer@comcast.net
Date: Sun, 16 Jan 2005 14:36:39 -0500
List-post: <mailto:towertalk@contesting.com>


Tom Rauch wrote:
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 you build your station to code or use common sense on
external cable and power entry that will never be a major
issue.


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.

That's generally NOT how it works. The path isn't a loop
from one piece of equipment to another via a ground buss
connection, it's generally from the improperly installed
antenna feedlines to a power line or telco ground through
the equipment.

The station ground should be neither for RF or lightning. It
should be for safety.


With individual ground leads to the ground window there

is no loop

through other equipment. Not always doable but it is the

proper way.

Not true at all. There are many paths between equipment in a
typical station. That's why a good low resistance ground
buss is generally a very distinct advantage.

73 Tom


It all depends on what you are trying to accomplish. If you are only worried about a safety ground then the "green" equipment wire ground should be sufficient if all is "properly installed" as professed. But we all know proper installation of all equipment is rather rare.


If you are wanting a true single point ground system to help with lightning suppression then doing as I described is the proper way to do it. You do not want ANY alternate path into any equipment chassis.
As I said it is not always doable though. In the case of most ham equipment it is very difficult to achieve. The transceiver is always tied to the amplifier via several cables at the operating position etc. In this case both should be bonded together and then to the ground window.
If there is say a 2 meter transmitter near by without connections to the hf equipment it would be beneficial to have its own ground lead to the ground window.
That will further isolate each equipment by not providing a second path for any lightning to exit through some other equipment.
Probably in most typical ham shacks it will be impractical to do separate leads back to the ground window. I am just pointing out the ideal protection scheme for equipment survival.


73
Gary  K4FMX



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