Friend here had one with KLM KT34 on top. Antenna was rotated by long mast
to rotator mounted at base. No torque from antenna was transmitted to
tower. Worked flawlessly through several bad storms here in Houston area.
Keith NM5G
-----Original Message-----
From: towertalk-bounces@contesting.com
[mailto:towertalk-bounces@contesting.com] On Behalf Of Doug Renwick
Sent: Wednesday, April 13, 2005 1:03 PM
To: towertalk@contesting.com
Subject: [TowerTalk] Rohn HDBX48 failure
Interesting. I see that the specs. for a HDBX48 are a 18 sq. ft antenna
max.
at point 3 ft above the apex of the tower for a 70.7 mph wind .
With a note: "antennas developing a large twisting moment due to wind must
not be used on this tower. Antennas should be limited to those having
maximum boom length of 10 ft. No engineering data relating to the use of
boom lengths in excess of 10 feet is available and the use of such boom
lengths is not recommended."
I am surprised at the high (18) square footage they have calculated. They
also appear conservative in their max. boom length mainly because they have
not done the calculations. They are also saying that for this self
supporting tower that failure will likely be from a twisting moment.
Chuck. The devil is in the details. Please share with us the details of
your loss. Was your HDBX48 sensibly guyed? Share how you had guyed the
tower. Did the guys break or pull out first? Was the tower guyed at the
top and also lower? What was the wind speed? Was it a hurricane or
tornado?
How long a mast did you use? How far above the apex of the tower was the
KT34XA mounted? Did the mast collapse first? Was the HDBX48 mechanically
sound?...i.e all cross braces in place and secured.
Doug/VA5DX
Chuck Sudds wrote:
> Yes Dave, *I* was one of those idiots who attempted using an HDBX48
> tower to hold up a KT34XA and a 14 element 2 meter beam atop that!!
> Unfortunately, I can no longer find any of the photos of that disaster
> of 7 years ago, it is still etched firmly in my memory! DON'T DO IT!
> I was lucky..... nobody was killed or injured! And yes, I even had
> mine guyed!! I sure do sleep better with my 100ft Rohn 45G properly
> guyed these days though. Do what the manufacturer says!!
>
> Chuck KØTVD
_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless
Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any
questions and ask for Sherman, W2FLA.
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather
Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
and ask for Sherman, W2FLA.
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|