[Towertalk] Rohn 25G foundation requirements

n4kg@juno.com n4kg@juno.com
Mon, 29 Jul 2002 10:01:08 -0600

I favor the tower in the ground approach.  I've started several towers
in the ground with NO guys, going up to ~25 ft to connect the first
set of guys.

I also suggest one set of guys, even if they are closely spaced.
For short towers, 80% guy anchor distance is NOT needed, assuming
a small antenna load.  Also, ANY guy is better than NO guy.  

FWIW, I would also put the antenna at 40 ft, assuming flat ground.
At this height, nearly ALL of energy in the first lobe will be refracted
back to earth.  Below 40 ft, a significant amount of energy is lost
(not refracted back to earth from 10 thru 20M).

Tom  N4KG

On Mon, 29 Jul 2002 "Mike Morrell" <morrellm@adelphia.net> writes:
> I am going to install an unguyed, free-standing 30' high Rohn 25G 
> tower and wish some information about various foundation 
> requirements.  
> Some info I gleaned from the Rohn website state that I should imbed 
> a short section of 25G in a  4' X 4' X 4' deep block of concrete 
> reinforced with # 7 rebar on a 12" pitch/grid pattern.
> Others at the local club suggest using the Rohn 25G self supporting  
> 1/2" thick plate that is anchored at  it's  corners with 5/8 " 
> anchor bolts imbedded to a concrete block.
> My plans for the tower are as follow:  1) the lightest HAZER system, 
> 2) a CDII rotor and 3) a Mosley Mini 33 triband. 
> The Mosley published loading is 2.5 sq. ft.
> Any comments about the various foundations and suggestions are 
> appreciated!
> 73 de Mike K8KE
> morrellm@adelphia.net
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