Thanks for answering.
MARB at the bottom (at the top Murphy’s law would have it fail quickly) - I’m
planning on using a smaller StepIR 3E with 30/40m element, which has 8.1 sq ft
wind loading. I have asked for the mechnical drawings. I assume there is some
kind of bottom support with a bearing of some type.
Any other thoughts?
Bob n2oml
> On Apr 1, 2015, at 7:12 AM, ve4xt@mymts.net wrote:
>
> Hi
>
> More important than the tower is how big is the antenna. Is it within the
> tower's spec?
>
> Are you mounting it on the top plate or using the MARB rotating base?
> Rotators such as the Ham IV are severely de-rated when mounted outside a
> tower (ie. without a thrust bearing above). Also, the Ham IV is quite
> optimistically rated for 15 square feet, but a long boom and heavy antenna
> can stress it quite a bit even if within the 15 square feet. As an example of
> de-rating, the Ham IV falls to 7.5 square feet when mounted outside (or on
> top of) a tower.
>
> 73, Kelly
> ve4xt
>
> Sent from my iPhone
>
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