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[TowerTalk] Pier pin vs. burying in concrete

To: <>
Subject: [TowerTalk] Pier pin vs. burying in concrete
From: (Kurt Andress)
Date: Sat, 02 Jun 2001 11:50:44 -0700
Steve Maki wrote:
> Steve Maki <> wrote:
> >"Stan Stockton" <> wrote:
> >
> >>On Kurt's website he makes the following observation referring to a tower
> >>that is mounted on a pier with the equivalent of a ball socket mount:
> >>
> >>"Putting the tower on a free base connection has allowed us to increase the
> >>antenna loads by 49%."
> >>
> >> I am interested in a practical means of achieving this type of free
> >>rotating base. Will be out of town for 8 days, but will be interested to see
> >>if someone has a good, practical way of achieving this.
> >
> >IF the Rohn flat plate were strong enough, one could simply place a
> >small spacer, like a large nut, around the pin & under the plate.
> >
> >So the obvious solution would be to beef up the Rohn plate to an
> >appropriate thickness. I would guess 3/4" would do it for normal
> >ham installs. Kurt?
> As K3KO just pointed out to me, one might be concerned about the
> ability of the concrete base to support all that force and friction
> at one small point. A second thick plate, under the nut, should take
> care of that.
> 73,
> --
> Steve K8LX

Hi Steve and All,

The larger towers in the Rohn commercial catalogue use only a tapered base
section and a bearing plate between the tower and footing that is machined
so it has a small diamaeter under the tower and a larger one against the
footing. There is an option to insulate the tower from the footing.

You can see the details in Dwg B700216 for Model "C" tower, Dwg B690343 for
the Model 80 tower, Dwg C730307 for the model 90 tower. 

73, Kurt, K7NV

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