[TowerTalk] tower specs/not wind loads

[ersmar@comcast.net]

Mike:

     You're correct - the BX-series of antennas has a torque limit on them.  This is because they are assembled with rivets, not welds, between the cross pieces and between the cross pieces and the legs.  The rule of thumb with these towers is that a ten-foot long boom would impart just about the maximum safe wind-induced torque on the tower.  A longer boom might twist the thing apart.

     Caveat Amateur.

73 de
Gene Smar  AD3F


 -------------- Original message ----------------------
From: "Mike Brown" <k9mi at sbcglobal.net>
> I may be completely off base with this, and if I am, I'll apologize right 
> now. With the Rohn BX, and HDBX series of towers, the "square foot" changes 
> according to model. But I swear, I thought I read that they all had a rating 
> on them that said not to use an antenna with a  boom over 10ft. Is that 
> right, or did I just read the specs wrong?
> 
> 73, Mike K9MI
> 
> 
> ----- Original Message ----- 
> From: <N0OEL at aol.com>
> To: <Steve at bnjcomp.com>; <towertalk at contesting.com>
> Sent: Tuesday, January 24, 2006 04:39
> Subject: Re: [TowerTalk] tower specs/not wind loads
> 
> 
> > Many of the towers made today are designed to sway and you dont want to 
> > guy
> > them such as the popular line of Universal Aluminum  towers.     The steel
> > towers are built to be self supporting  to a certain height as described 
> > by their
> > engineering specs.     The same with the Aluminum towers and you should 
> > pay
> > big attention to their  specs.   The 40 foot Rohn 25G
> > wont hold a lot when self supporting.    In fact  outside of a small beam
> > forget it without a set of guys!
> >
> > Rohn will tell you the size tower they advise and if its 25 G pay attn to
> > the need for guys.    If its HDBX dont try to guy it as its  designed to 
> > sway
> > Towers all vary as to max height and  that height should depend greatly 
> > not
> > on what you want but as to the antennas to  be put on them and that 
> > antenna's
> > windload.    Antennas should be  a certain height above ground depending 
> > on
> > what bands you intend to  work.    I personally think that the good DX 
> > starts at
> > 50 feet  with the average triband beam.    Dont try to impress the
> > neighborhood with big towers but build what is necessary and safe.    BTW 
> > the 56 foot
> > HDBX Rohn is small in
> > windload capacity and safer if you build it to just 48 feet!
> >
> > Pay big attention to windload and the specs of the beam and the tower 
> > before
> > you determine height of your tower.    My triband Higain  is at 50 feet
> > selfsupported aluminum with a 26 inch base.    I have 5.5 sq feet of 
> > concrete
> > holding it up.    And it  works great. And yes, it does have some sway as 
> > much as 6
> > inches as it is is  designed.
> >
> > Good luck!
> >
> > 73
> > Mike
> > K0BUD
> > _______________________________________________
> >
> >
> >
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> 
> 
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