In a message dated 1/16/2010 4:23:25 A.M. Pacific Standard Time,
towertalk-request@contesting.com writes:
> I must be a heretic on tower building. If I were an engineer, I'd
probably
still be designing my first tower.
If you were an engineer, you'd be observing Laws of science as well as
engineering and legal codes - not "back of the envelope" estimates.
> I can see stress tensioning the guys on
a 600' commercial tower, anyone can, but on 50' or 60' of Rohn 25 I really
do not see the need to get wrapped around an axle over it. In the older
catalogs, 40' was self supporting.
I think this was an old wive's tale (which I have in the past repeated
myself). I've never seen that statement in any Rohn literature so I don't
know where it came from ("I put it up and it didn't fall over"?).
OTOH Rohn towers are well known to endure amateur radio overloading
conditions on a regular basis without failure.
> It wasn't until the lawyers got involved that it had to be guyed at 20
through 40 feet.
While it's true that tower manufacturers are Insurance-driven
enterprises, the industry wide adoption of the original EIA-222 Tower Standard
made
manufacturers re-calculate their towers in light of these new standards
and publish new specifications.
> My thoughts, as wrong as they may be, are that the guys on a 60' tower
only
need to be tight enough to keep the tower vertical.
So I expect your guys to be way under-guyed which has the potential to
introduce wind-induced guy wire slamming as the wind gusts and the tower is
forcibly pushed to the end of the guy travel.
> I've never pulled a
guy wire more than hand tight on a turnbuckle. What would be the need to
apply much more vertical and horizontal stress on a tower? If the tower
flexes
one inch in a strong wind the guy wire on the windward side will tighten
and apply the necessary force to stop the tower movement. The middle guy
wires only need to be snug enough to keep the center sections of the
tower
from doing the hula.
Major violations of the LXC Prime Directive to "DO what the manufacturer
says" aside, some of your advice is potentially dangerous and contrary to
industry and manufacturer's specs. I'd say you've been lucky but then every
time you speed you don't get a speeding ticket, do you?
Cheers,
Steve K7LXC
TOWER TECH -
Professional tower services for hams
Author of UP THE TOWER - the first tower book ever written
_www.championradio.com_ (http://www.championradio.com)
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