[TowerTalk] US Tubular tower

[Kelly Johnson]

The MA550 should be able to handle a 2 element SteppIR to at least 70
mph according to the MA550 specs.  In fact, it should be able to
handle a 3 element SteppIR at that windspeed.  US Tower claims the
MA550 can hold 9 sq. ft and 65 pounds at 70 mph.  A 3 element SteppIR
is only about 6 sq. ft. and about 45 pounds I believe.

The bigger question is the rotatable dipole 10 feet above the top. 
That's likely to be a bigger problem.  Every foot you increase above
the top significantly decreases the allowable wind load.

Yes, keeping the tower down when not in use is always a good idea IMO.
 The problem with assuming it will be down when winds are high is that
it doesn't cut it with some building inspectors and zoning
regulations.  I can name at least one zoning ordinance that
specifically prohibits loading a tower beyond its rated wind load
rating, regardless of whether you plan to leave it down when winds are
high.


On 7/25/05, Rick Karlquist <richard at karlquist.com> wrote:
> I have an MA550 with 2 element Steppir 6 inches above the top of the
> tower.  According to the UBC calcs that came with the tower, this is OK up
> to winds of 50 or 60 MPH.  You should plan to crank it down in the event
> of a severe storm that may reach 70 or 80 MPH.  FWIW, the MA550 had a KT34
> on it during the '89 earthquake and stayed up, although it moved a lot.
> 
> Rick N6RK
> 
> 
> 
> Richard D. Markel wrote:
> > I must use a tubular tower in my location.
> >
> > I plan on installing a 55 foot US MA 550 tower with motor pull-down
> > drive.  I have tentatively decided on a Steppir two element beam (specs
> > aren't too shabby for such a short boom) either bolted directly to the end
> > of the top section of the tower or only 6 inches above the tower on the
> > mast.  The mast itself would have a total length of 10 feet with about
> > seven feet protruding above the tower.  At the top of the mast would be an
> > Optibeam 40 meter rotatable dipole.  Total wind load would be about 7.5
> > feet with a total weight (not including mast) of about 50 lbs.
> >
> > How does this sound?  Is the MA 550 up to it?  I think this is the best I
> > can do at this location and still get a forty meter antenna up at
> > acceptable height.
> >
> > Your thoughts would be appreciated.
> >
> > Tnx
> >
> > dick - KB6VT
> >
> >
> > _______________________________________________
> >
> > See: http://www.mscomputer.com  for "Self Supporting Towers", "Wireless
> > Weather Stations", and lot's more.  Call Toll Free, 1-800-333-9041 with
> > any questions and ask for Sherman, W2FLA.
> >
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> 
> 
> _______________________________________________
> 
> See: http://www.mscomputer.com  for "Self Supporting Towers", "Wireless Weather Stations", and lot's more.  Call Toll Free, 1-800-333-9041 with any questions and ask for Sherman, W2FLA.
> 
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