Topband: Spark gaps

[N2TK, Tony]

As a side note, last night when the storm came barreling in with very strong
winds I was watching the tower as the elements whipped around. Bang! First
time I saw a direct hit on the tower. Had spots in my eyes for a while.
Tower is about 150' from the kitchen window.

I had everything tuned off but I never disconnect anything.
Was anxious when I turned on things this morning. Everything is fine except
the fuse blew on the Prosistel when I turned it on. Replaced the fuse and
everything is now fine.
I guess my ground system is working. Couldn't find any burn marks anywhere
inside or at the tower. With no visual or electrical damage maybe the tower
has been hit before? 

By the way the tower is grounded and I shunt feed it for 160M.

73,
N2TK, Tony

-----Original Message-----
From: topband-bounces at contesting.com [mailto:topband-bounces at contesting.com]
On Behalf Of donovanf at starpower.net
Sent: Friday, July 27, 2012 10:58 AM
To: topband
Subject: Re: Topband: Spark gaps

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-4f11-4ed
9-8e89-9fea015509e5&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 at w8ji.com>
>Subject: Topband: Spark gaps
>To: "topband" <topband at 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