On 4/14/2012 7:17 PM, W2RU - Bud Hippisley wrote:
> This is so "not a problem" by using either:
> a. Four standard 25G sections plus a 25AG4 top section; or
> b. Five standard 25G sections plus the 1-ft 4-in BAS25 Rohn
> bearing/accessory shelf section.
I'll have a Force 12 C19 XR about a foot above the top of the flat plate
with a WARC 7 about 10' above it. With the 4.9 sq ft of wind area from
the WARC 7 that would produce the leverage, or bending moment of 49 sq
ft at the top of the tower. 58.8 if I went the full recommended 12'.
Both far exceed the rating for a 50' guyed 25G.
With the rotator mounted down in the tower the bending moment is
mostly gone and it's more or less a side force. On the 45G I mount the
rotator close to 30 feed below the top. The only places I've found the
accessory shelf fits properly is between the sections. Having worked
on a lot of equipment I was always taught that if it has to be forces it
> In either case, a TailTwister is easily mounted near the top of the top
> section, with provision for a TB-3 (2-in mast) thrust bearing a foot or so
> above the rotator.
> But I have also inserted a TailTwister into other Rohn 25 sections by angling
> it properly and putting a little bit of temporary pressure on one of the
The tail twister and Ham series are pretty much the same OD. It takes
well over a 100# of pressure to bend either welded brace between a half
to 3/4 of an inch to get the ham IV or V in there. The IV and V are the
same rotator, only the control is a little different. To me a "little
bit of temporary pressure" is something I can do with my bare hands and
that is definitely not the case here.
It's beginning to appear that the 25G is not suitable for these two,
relatively small antennas.
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