[Towertalk] MW BC tower insulator swap method

[Rob Atkinson, K5UJ]

I have to confess at the beginning that I was only interested in how they 
handled a lightning strike. I didn't think until later that I should have 
asked about equipment rf grounding and so on.  In fact there were a bunch of 
things I wish I had asked but you can't think of everything.  Anyway, medium 
wave broadcast stations in the U.S. seem to all have antenna designs that 
happen to be great for dissipating strike energy because they have these 
really good radial systems.  This one was a relatively low power station 
(around 250 watts).  The tower was 5/8 w. & made by Rohn, around 370 to 400 
feet tall with a beacon on top and lights halfway down.  Each side was about 
a 15" wide.  Can't remember if it was 3 or 4 sides.  It tapered down to the 
insulator which went from about 8" down to 6" in diameter and 4 or 5 inches 
thick. Instead of spark balls they had a short rod about the size of a 
railroad spike coming up from the ground to within 3 to 5 mm of the tower.  
I guess the gap could be that small because of the low tx power.  The 
insulator sat on a concrete base about 3' square.  there were four 4" wide 
metal straps going down around the base to a buried loop around the base 
that the radials were tied to.  They had a radial every 3 degrees & all were 
one or two inch wide heavy gauge braid buried under the grass.  So it looked 
like when the tower got hit all of the energy would simply come down, jump 
the gap and fan out on the radials.
Assuming a ham with a tower has the room, I wonder how much more protected 
his station would be if he (this assumes he's not using the tower as a 
radiator) buried 120 heavy guage radials all one or two hundred feet long 
and bonded them to the base of his tower?  Would this divert most or all of 
the current?  Sorry I didn't come up with more useful information.

73,
Rob Atkinson
K5UJ
k5uj@hotmail.com


----Original Message Follows----
From: "Bill Hider \(N3RR\)" <n3rr@erols.com>
To: "Rob Atkinson, K5UJ" <k5uj@hotmail.com>,<towertalk@contesting.com>
Subject: Re: [Towertalk] MW BC tower insulator swap method
Date: Thu, 16 May 2002 08:58:31 -0400

Rob,

So tell us about how they did their grounding!!

Bill, N3RR


----- Original Message -----
From: "Rob Atkinson, K5UJ" <k5uj@hotmail.com>
To: <towertalk@contesting.com>
Sent: Wednesday, May 15, 2002 2:19 PM
Subject: [Towertalk] MW BC tower insulator swap method


 > Hi you guys:
 > stuff deleted
.  I wanted to see how the
 > pros did their grounding, counterpoise connections, and insulation of the
 > tower.  I expected to be told we couldn't get close because of liability
but
 > to my surprise the guy showing us around let us gather around the tower
 > base.
stuff deleted
 > 73,
 > Rob Atkinson
 > K5UJ
 > k5uj@hotmail.com
 >
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