My 40 HDBX has closer to 6 yards under it. It's a block 6.5 square, 6 ft
deep. The old Rohn drawings specified a 4' deep hole. I also have a yard
of gravel in the bottom of the hole to prevent ice lensing. (Which at 6
ft deep shouldn't ever happen here in 4 land! HIHI)
I take the Walt Disney mantra of engineering, take what you know, design
it to your best, then "plus" it to make it better.
73!
-Adam
On 5/13/2011 8:18 AM, WA8JXM wrote:
> Many years ago I had a 64' freestanding tower with a 3el triband beam (TA-33)
> on it. The base was only 2 cu yards of concrete. As far as I remember, that
> was all the manufacturer (Heights) recommended at the time.
>
> Now when I look at anyone's recommendations, the base requirements are much
> larger. Rohn (and others) recommends 3 cu yards even for a 40' BX tower.
> I had used only 1 cu yard for a freestanding 40' tower.
>
> Is my memory faulty, or have the recommended bases grown over the years?
> Were the old recommendations inadequate, or has everyone grown super
> conservative over the years? "If one yard is adequate, three will be
> better, so let's use five yards"???
>
> As one ham commented on the air yesterday, the only failures he has ever
> heard of were in the tower itself, not the base falling over.
>
> Ken
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