DO THE MATH FIRST !! YOU WILL SEE THAT FENCE POST IS NOT SUFFICIENT.
http://www.math.niu.edu/KARC/mast/
Bill N1HWC
On Wed, Aug 6, 2008 at 10:45 AM, <k1xx@cfl.rr.com> wrote:
> Julio:
> I don't totally agree with all your statements regarding top rails. I've
> used them very successfully in the past. Since this goes back a few years,
> my memories a bit fuzzy. But, I seem to recall that there might be a heavy
> duty top rail which is "just slightly" under 2 inch OD and not much smaller
> as you mentioned. I'd have to go out back and measure one to determine the
> actual size.
>
> In several cases, I used 12'ish foot lengths for yagis mounted at the top
> of the tower with the rotor recessed 10 foot into the tower. In one case, I
> had a full 20 foot length with a custom-turned insert placed down into the
> top rail. This one had a big 6 element 10 meter beam on a 3" boom at the
> very top (10 foot out of the tower). I can't count how many ice and snow
> storms that combo survived.
>
> If any mast material's overloaded, it will bend. Doing the analysis is the
> first best step.
>
> 73 charlie, k1xx
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