In a message dated 1/16/01 2:38:00 PM Pacific Standard Time,
w5ba@compuserve.com writes:
> Actually, all the back and forth on this caused me to go back and look at MY
> copy of the Rohn Ham Tower Catalog which shows a number of different
> scenarios:
> 1.) 110 MPH Basic wind speed ratings for everything from 40 to 170 ft.
> of 45G. (60 ft. will support 9.6 sf of antenna...guyed at 25 ft.
> with
> 3/16 EHS tensioned to 400# and 55 ft. with 1/4 EHS tensioned to
660#
> The same tower height, with a single 3/16 EHS 400# set of guys will
> support 16.7 sf at 70 MPH).
ACTUALLY there is another 8 sq.ft. of tower capacity available that was
netted out for a symmetrical commercial antenna mount in the general notes.
Take a look. So the above example will take 24.7 sq.ft.
> 2.) 70, 80 and 90 MPH ratings for everything from 40 to 100 ft. of
> bracketed 45G
> (60 ft. will support 33.3 sf at 70 MPH, 24.7 sf at 80 MPH and
> 17.0 sf
> at 90 MPH...bracketed at 23 and 46 ft. levels).
> What it does NOT show is any ratings for bracketed towers in excess of 90
> MPH
> wind speed ratings. My guess is they don't recommend it.
GOOD THINKING!
> That's not to say that it "can't" be done...
YES - that's exactly what that means - it can't be done.
> just that if you want to be sure that it is done
> safely, you'll get
> someone who is qualified to 'run the numbers' to check the installation.
> ARRL
> has a Volunteer Engineer program, similar to the Volunteer Counsel program
> for
> legal issues, and I'd wager you could find someone to take a look at your
> proposed
> installation for a LOT less than $1800/hr.
Yes, you can get the calcs run for a case of beer in some cases. But that
engineer will arrive at the same conclusion that the manufacturer has.
Cheers, Steve K7LXC
Tower Tech
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