[TowerTalk] Rohn tower installation specifications

Mike nf4l at att.net
Sun Apr 1 16:37:25 PDT 2012


My opinion, and that's all it is, is that Rohn's specs are CYA in this 
case. A lot will depend on what the house brackets are attached to. 
Fascia and siding doesn't give much support. With 2 brackets lateral 
force shouldn't reach the base.

GL & 73, Mike NF4L

On 4/1/12 3:24 PM, Dave Cook wrote:
> Hi guys, I'm in the process of relocating my 35' freestanding Rohn 25G tower
> after 8.5 years on the air. I figured this time I'll bracket it to the
> house, which is what I should have done in the first place. But I've run
> across a few problems with the Rohn specifications:
>
>
>
> 1.       The tower will be bracketed to the house mid-way up and also near
> the top of the tower with an eave bracket. The specifications for the
> brackets "must support a minimum horizontal force of 815 pounds". I can't
> find any calculations for how they came up with this number. And it seems
> very excessive for a modest 35 foot tower bracketed in two places.
>
> 2.       The specs also state that the base must be a "fixed base", rather
> than a pinned base. Again, in this case I don't understand why a pinned base
> wouldn't be sufficient for a well-bracketed tower. Why would the base
> experience any lateral loading?
>
> 3.       The specs also state that the base has to be the same 2x2x4 feet of
> concrete that was spec'ed for self-supporting and guyed towers. In this case
> I can understand somewhat having a solid chunk of concrete for the thing to
> rest on, but the entire weight of the tower and antenna will be, by my
> calculations just a little over 200 lbs. It doesn't seem to me that it needs
> a 2000 lb chunk of concrete to keep that from sinking into the soil.
>
>
>
> So in short, I'm just wondering if Rohn is simply CYA'ing themselves, or are
> these specs really to be taken literally?
>
>
>
> Thanks and 73,
>
> -- Dave WA0TTN
>
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