Note that Mike's 4 X 4 wooden base under a flat plate is
also another EASY way to achieve an INSULATED Base
for direct feed of the tower as a vertical.
With guyed towers, there should be ZERO lateral forces
at the base, all vertical so the main concern for a base is
that it be able to support the weight and resolved guy
tensions.
I remember vividly seeing the 19 R25 140 ft. towers at W1EVT's
hilltop location. EACH tower had a flat plate sitting on a
cinderblock base where the height of the cinderblocks
was adjusted so that each tower base was at the same
elevation for his wire arrays. To the best of my knowledge
he did not cement the blocks and there was NO pier pin
in sight. These towers have been standing for decades.
Tom N4KG
On Wed, 04 Sep 2002 Jon Ogden <na9d@speakeasy.net> writes:
> Mike,
>
> An interesting setup for sure. To be honest, with a guyed setup,
> you
> shouldn't need much of a base if you are on solid ground. I have
> been
> convinced by numerous people to use a pier pin assembly with the
> Rohn BPC25G
> base plate on top of a concrete pier. The rationale behind this as
> opposed
> to a section embedded in concrete is that as there are rotational
> moments on
> the tower, the base is free to move slightly. With a fixed base in
> concrete, all twisting forces are taken up in the tower itself. The
> only
> thing the pin does is to keep the tower on the concrete pad. Makes
> sense to
> me and made pouring the concrete, etc. a lot easier. To me, the
> pier is
> probably much bigger than needed for this setup (2'x2'x4') but it is
> certainly solid. Yes, you need guys all the time, but you are going
> to have
> them anyhow....
>
> 73,
>
> Jon
> NA9D
>
> on 9/4/02 8:20 PM, Mike Wetzel at mjwetzel@comcast.net wrote:
>
> > Jerry,
> >
> > My wood bases are comprised of 2- 6" x 6" x 4' long treated pieces
> of wood
> > covered with asphalt roofing compound. The pieces are laid
> horizontally
> > together, a Rohn base plate is attached to the wood with long lag
> screws and
> > on 2 diagonal corners of the pieces I have drilled holes and drove
> 1" steel
> > pipes into the ground. That's about all I remember about them
> because my
> > dad and I did this in about 1975. Obviously you can only put one
> section up
> > before you have to guy it temporarily to add more sections. With
> the 4' of
> > surface area, I have not noticed any sinking although I'm sure
> there must
> > have been some over the last 27 years. They probably won't last
> forever,
> > but.
> >
> > As I've said here before, I have no concrete on any of my guy
> anchors. For
> > the Rohn 25 towers just screw in anchors and truck driven 10"
> anchors on my
> > Rohn 45 (170') and 55 (150') towers.
>
>
> -------------------------------------
> Jon Ogden
> NA9D (ex: KE9NA)
>
> Life Member: ARRL, NRA
> Member: AMSAT, DXCC
>
> http://www.qsl.net/ke9na
>
> "A life lived in fear is a life half lived."
>
> _______________________________________________
> Self Supporting Towers, Wireless Weather Stations, see web site:
> http://www.mscomputer.com
> Call 888-333-9041 to place your order, mention you saw this ad and
> take an additional 5 percent off
> any weather station price.
> _______________________________________________
> Towertalk mailing list
> Towertalk@contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
________________________________________________________________
GET INTERNET ACCESS FROM JUNO!
Juno offers FREE or PREMIUM Internet access for less!
Join Juno today! For your FREE software, visit:
http://dl.www.juno.com/get/web/.
|