If you guyed a 70 foot 45G at 4 levels and put the top set at the top, it
would hold a HUGE load. I can't calculate how much since I am not an
engineer, but you should find one and suggest this configuration to him.
You will be very surprised at how much it will hold . . .
Stan
w7ni@easystreet.com
----- Original Message -----
From: "Michael Tope" <W4EF@dellroy.com>
To: <towertalk@contesting.com>; "Chuck Counselman" <ccc@space.mit.edu>
Sent: Monday, September 30, 2002 1:06 PM
Subject: Re: [Towertalk] 45G (guyed) vs. SSV (self-supp'g) 70-ft. tower
> I will probably get flamed for this, but I can't resist. Aren't those Rohn
> specs for 45G super conservative (8sq ft at 90 MPH) because they
> place the top set of guys so far below the top of the tower? I would
expect
> that a properly guyed 70' x 45G tower would be capable of holding up
> 20 sqft+ in a 90 MPH wind if the top set of guys were placed reasonably
> close to the top of the tower. For that reason alone I would go with the
> 45G tower. On the other hand, getting antennas on and off the guyed tower
> is a little more work (tram line) versus straight up and down. Also if you
> are interested in vertically stacking antennas along the length of the
tower
> you have the problem of guy wire interaction to worry about. This can be
> solved by going to Kevlar or Fiberglass guys, but I think it adds to the
> cost (versus steel guys):
>
> Rohn 45
>
> PROS
> Smaller base
> Larger antenna windload capacity - 20sqft (with properly engineered guy
> system)
> Fall zone probably smaller (heaven forbid)
>
> CONS
>
> Steel guy wires need to be broken up or replaced with insulated material
> Tram line needed to remove/install antennas
> Guys vulnerable to falling trees and vandalism (kevlar vulnerable to fire)
> Probably less appealing to neighbors
>
> SSV Tower
>
> PROS
>
> Antennas easily hoisted up and down
> No Guy wires and guy wire electrical interaction
> More appealing asthetically (to non-hams)
>
> CONS
>
> Lower windload capacity
> Larger concrete base
> Probably has (or a least potentially has) a larger fall zone
>
> That is the trade space as I see it, Chuck. I would probably
> opt for the 45G if it were me.
>
> Good luck!
>
> 73 de Mike, W4EF.............................................
>
> ----- Original Message -----
> From: "Chuck Counselman" <ccc@space.mit.edu>
> To: <towertalk@contesting.com>
> Sent: Monday, September 30, 2002 7:15 AM
> Subject: Re: [Towertalk] 45G (guyed) vs. SSV (self-supp'g) 70-ft. tower
>
>
> > At 8:59 AM -0400 9/30/02, K7LXC@aol.com wrote:
> > >In a message dated 9/29/02 8:48:19 PM Pacific Daylight Time,
> > >ccc@space.mit.edu writes:
> > >
> > >> Can anyone give me an estimate of the overall cost of each
> > >> alternative (45G or SSV), considering not only the tower itself but
> > >> also the foundation work, professional erection, and guying (for
the
> > >> 45G)?
> > >>
> > > > In other words, what's the net cost of doing without guys?
> > >>
> > >...You can gather the steel costs yourself - check Texas Towers or
other
> > >Rohn dealers.
> >
> > I'd already done that. The difference in steel cost is not
> > significant. The _erection_ of a 70-ft. SSV tower is what worries me.
> >
> >
> > >...if you want the least expensive 100' antenna structure and
> > >have the real estate and spousal approval, you can't beat a guyed
system.
> >
> > I know that a guyed system is cheaper, but by how much? $3k, $30k,
> > or what? Just approximately.
> >
> > I'm short on real estate. Guy anchors would have to go in the
> > "setback(s)" of my lot. Obtaining zoning approval may be difficult
> > and could force me into compromises that I want to avoid.
> >
> > -Chuck, W1HIS
> >
> >
> > _______________________________________________
> > AN Wireless Self Supporting Towers at discounted prices,
> > See http://www.mscomputer.com
> >
> > Wireless Weather Stations now $349.95. Call Toll Free,
> > 888-333-9041 for additional information.
> > _______________________________________________
> > Towertalk mailing list
> > Towertalk@contesting.com
> > http://lists.contesting.com/mailman/listinfo/towertalk
> >
>
>
>
> _______________________________________________
> AN Wireless Self Supporting Towers at discounted prices,
> See http://www.mscomputer.com
>
> Wireless Weather Stations now $349.95. Call Toll Free,
> 888-333-9041 for additional information.
> _______________________________________________
> Towertalk mailing list
> Towertalk@contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
>
|