On Aug 16, 2007, at 12:18 AM, KC8DDQ@aol.com wrote:
> I'm getting ready to put up a 20 foot Rohn 25 tower. I was
> planning on pouring a 20"x20"x42" concrete base. I will be
> anchoring a Rohn base
> plate to the concrete with four 36 inch 3/4" galvanized all thread
> anchors
> set in the concrete. The tower will be free standing.
This is not what the manufacturer recommends. See here:
http://www.radiancorp.com/ROHNNET/rohnnet2001/catalog/pdfs/25G/25G-1.pdf
Look at note #2 -- Fixed bases must be used, "Pinned" bases cannot be
used.
Here's the diagram of the fixed base:
http://www.radiancorp.com/ROHNNET/rohnnet2001/catalog/pdfs/25G/25G-2.pdf
Look carefully at the dimensions -- note that the recommended base is
FOUR FEET square, and four feet deep. Your 20"x20"x42" base is way
too small.
Even the standard base is 24"x24"x48":
http://www.radiancorp.com/ROHNNET/rohnnet2001/catalog/pdfs/25G/25G-4.pdf
Your proposed base is too small for any conceivable use of Rohn 25G.
--
There was a recent mini-article in QST where a guy discussed the use
of a 18" Sonotube to pour his tower foundation. The picture clearly
shows Rohn tower sections. Unfortunately an 18" diameter base is too
small. You'd have to use a 24" Sonotube for Rohn 25G.
Bill Coleman, AA4LR, PP-ASEL Mail: aa4lr@arrl.net
Quote: "Not within a thousand years will man ever fly!"
-- Wilbur Wright, 1901
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