[TowerTalk] Would like to post to the Tower Talk list

[Robert Ross]

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 at 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
>