An air gap using one to two inch diameter balls with only a one or two
millimeter gap provides a nearly uniform field resulting in the fastest
breakdown at repeatable and fairly breakdown voltages but capable of
withstanding kilowatt transmitter power levels.
Ordinary carbon steel balls used in architectural applications should provide
adequate protection if they are inspected -- and replaced if necessary -- after
a lightning strike. For example, Wagner Industrial sells two inch diameter
threaded steel balls for $11.00 each. There may be alternative sources.
http://www.shopwagnerb2c.com/SPHERES/SPHERES_ST?categoryId=315e03cf-4f11-4ed9-8e89-9fea015509e5&filters=&sortby=1&page=1&pageSize=10&criteria=
Very hard steel balls such as carbon or tungsten are ideal for withstanding
multiple lightning strikes without need for inspection and replacement, but at
higher cost.
The balls should be aligned in the horizontal plane, to ensure rain, do not
bridge the gap. Preferably, the balls should be installed in a
weather/insect/rhodent proof enclosure.
73
Frank
W3LPL
---- Original message ----
>Date: Fri, 27 Jul 2012 10:09:16 -0400
>From: "Tom W8JI" <w8ji@w8ji.com>
>Subject: Topband: Spark gaps
>To: "topband" <topband@contesting.com>
>
>Has anyone looked at, or looked for, cheap electric fence gaps??
>
>My system copper pipes near tower legs work great for me on rigid towers, I
>can bend them so they spring away from the tower and then slide an inner
>pipe in or out to set gap distance. I'm thinking of gaps for wire antennas.
>
>Maybe something is good from some other application that is a good bit
>better than a spark plug.
>
>_______________________________________________
>UR RST IS ... ... ..9 QSB QSB - hw? BK
_______________________________________________
UR RST IS ... ... ..9 QSB QSB - hw? BK
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