The answer depends on what you plant to put on the tower. For most ham
applications, a pier pin base is not necessary. This arrangement is
used to reduce stress on the legs caused by the twisting induced by very
large antennas. You can also reduce this stress by using a 6 guy torque
arm arrangement on top, the method I prefer. It is also more difficult
to erect a tower on a pier pin base. You can either erect the sections
up to the first guy all at once with a crane, or temporarily guy the
first section until you get to the first guy point.
73
Dave Colter WA1ZCN
Lowell, Mark wrote:
>
> Which is more acceptable/desirable as a base for 110' of guyed R25G?
>
> 1) Short tower base section submerged in concrete.
>
> 2) Separate concrete base with anchor bolt/pin and a base plate adaptor.
>
> Does method 1 require additional rebar or does the tower section provide
> all the reinforcement that is necessary?
>
> Does method 1 allow better grounding if the portion of the base section
> that extends below the concrete is tied into a ground rod, carrying
> lightning strike current in the shortest path through the concrete?
>
> Is the torque control provided by method 1 even necessary or desirable for
> a guyed tower?
>
> It sure seems easier to just make a flattop base, except for the work to
> buy, bend, and build some sort of rebar cage. What kind of rebar cage does
> this require?
>
> Most of the locals here are making simple concrete cubes with no rebar and
> a single j-bolt.
>
> Since Rohn sells parts for each style of construction, I am unsure which
> type they are really recommending. However, it would appear that the only
> base drawing they show in their catalog favors method 1.
>
> Thanks for the help,
>
> --...MARK_N1LO...--
>
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