Brahmangou@aol.com wrote:
> Whenever I pour 25G tower into the concrete base I drive a 10 foot section
> of galvanized plumbing pipe up each leg first. It's cheap and really
> stiffens up the tower when you climb it.
With the guys properly tensioned I'd think the tower would be plenty stiff.
> I'm sure there are several engineers on
> the list that will tell you never to do that, I'd kind of like to hear why.
>
I'd be a bit concerned about moisture being trapped between the pipe and
tower leg as well as the possibility of damaging the galvanizing on the
inside of the tower legs.
Up to 60 feet and bracketed, I still use dirt bases for 25G, but I don't
put anything monstrous on them either. Then again, our one acre lot is
surrounded by large trees that are considerably taller than 60' so an
antenna at 60' is relatively protected. I prefer to make the bases out
of 3/4 or 1" X 5' solid steel for the legs and weld 6" wide X 1/8"
steel plates across the legs. Each leg gets a pair of 1" wide by 4" long
X 1/4" thick plates welded on and drilled to create a hinged base. I
set the spacing by just inserting the legs into two tower sections and
then welding the plates onto them. It makes for a fast and accurate
assembly. I sand blast them and then give them a good coat of Rustoleum
primer, followed by a finish coat. They are very heavy, but quite
durable and I don't have to worry about water in them.
OTOH that much steel costs darn near as much as the commercial dirt base
from ROHN, or did. I don't think they are still available.
73
Roger (K8RI)
> FWIW.
> 73,
> Marty AB5GU
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