Rick
I install a Trylon T-200 96ft like 9 years ago for a client who in that
time he was in the need for 2 or maybe 3 at most wireless links using 60 cms
dish antennas very light in weight
5 years later the tower was loaded with 14 of those ( great news for my
wallet, but my mind was not very relax thinking in overload tower) and later a
new ISP in town install a 10ghz 3ft dish like 100 pounds all at 65ft to
provide broadband
internet to this client, weeks later they complaint about some loss in windy
days around 20-25 mph and significant loss when winds over 30 mph where
present, just in the 10ghz antenna.
My recommendation was to add 3 guy wires below the dish and works perfect
with winds gust over 50 mhp and my mind rest , but 2 years later 2 more ISP
add 1 similar antennas just above the other and other at 80ft smaller but
little heavy
when saw that push the client to get another set of guy wires at 80ft level,
to avoid movement and the collapse of the tower in a worst case scenario
The guys wires are simple philly 1200 and 3/8 turnbuckles just with the
minimum tension on the tower using custom made guy brackets , the anchors are
elevated and far from the tower and the tension on the guy wires is just the
minimum needed
to keep the tower stable.
I'm not engineer but apply the logic and caution in this "solution" and is
working , and do not see why can not be used in others tower, yes the HBX
are too light for that on extreme weather, maybe swapping all the rivets for
bolts and nuts. moving the
rotor to the lower part of the tower and adding a special custom made anti
sway bracket, 6 guys and big separation anchors from the tower base, can work,
but can be more expensive than get a real tower like heavy Trylon or AN
tower to fight the torque
This is my experience and my practical idea
J.Hector Garcia XE2K / AD6D
Mexicali B.C DM22fp / El Centro
P.O.Box 73
El Centro CA 92244-0073
http://xe2k.net
Tweeter @XE2K
________________________________
From: Richard Karlquist <richard@karlquist.com>
To: towertalk@contesting.com
Sent: Monday, August 12, 2013 2:06 PM
Subject: [TowerTalk] Adding guys to self supporting towers
The topic of adding guys to self supporting towers has been
discussed a number of times on this reflector, but I am
still not clear on exactly why it supposedly won't work.
If I have figured crrectly, the worse case compressive load
on a leg at the bottom of a trianguler tower
is equal to the product of the horizontal windloading
at the top times the factor h/[w*sqrt(3)] where h is
the height and w is the width of a face.
For example, a 100 ft windload at the top of a 50 foot
tower with 18 inch face will induce 1925 lbs of
compressive force. If a the tower is guyed at the top
with the guys at 45 degree angles, the compressive
force is simply equal to the horizontal wind load, or 100 lbs.
Much less than the unguyed 1925 lbs.
It seems to me the guyed tower is much stronger and could
handle a considerably larger wind load based on this
simple analysis.
The only way I can see that this wouldn't work is if a
larger antenna resulted in torque loads that the tower
couldn't handle. For example, the HDBX series, well known
for its poor torque strength, would be a poor candidate
for guying. OTOH, a light weight tower with a large
face width might be able to take a lot of torque. To
facilitate this, you might want to build the tower with
less taper than it typically has in the self supporting
configuration, or maybe no taper. All of this depends
on wind area and boom length.
Comments?
-- Rick Karlquist
N6RK
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