On Tue, Oct 15, 2002 at 09:57:32AM -0400, K7LXC@aol.com wrote:
> In a message dated 10/14/02 10:08:24 PM Pacific Daylight Time,
> stetrekve@yahoo.com writes:
>
> > This makes only 14-15' above the tower and whatever it
> > takes to the rotator, which I hear will only fit in
> > the top most part of Rohn 25?
>
> Your configuration and spacing sounds okay.
>
> For 25G, the rotator will ONLY mount in a taper-topped section or at a
> leg joint. A HAM IV will go in but you'd need to take out a diagonal in order
> to get a T2X in there.
A 2-3/4 mast won't fit through the tube of a 25G tapered section. The
M2 web site doesn't give dimensions, but says a 2800 will fit inside
25G. Installation might be "interesting" however.
One problem I see it that this seems like a fairly large load for 25G.
Looking at the wind loading:
Comet GP-9: Not specified, assume 1 sq. ft.
M2 2M5WL: Force 12 doesn't spec this, however the similar Cushcraft 17B2
is specified at 3.5 sq. ft.
M2 6M7JHV: Specified at 2.5 sq. ft (which looks a bit low to me).
Force 12 5BA: Specified at 11 sq. ft.
The projected area of 15 ft. of 2-3/4 mast is about 3.5 sq. ft.
These total 21.5 square feet. According to the FCC database, K7AWB is
in Spokane county, which has a 70 mph wind speed rating. Rohn 25G is
specified for 18.4 sq. ft. with a single set of guys at 40 feet, 70 mph
wind speed, so the installation would be pushing things a bit. YMMV,
but I think a more conservative approach (heavier tower or smaller
antennas) should be considered.
73,
Bob, N7XY
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