I just looked in my Rohn Ham Tower Catalog, and for the BX/HBX/HDBX towers, it
says:
"NOTE: ANTENNAS DEVELOPING A LARGE TWISTING MOMENT DUE TO WIND MUST NOT BE USED
ON THIS TOWER. ANENNAS SHOULD BE LIMITED TO THOSE HAVING A MAXIMUM BOOM LENGTH
OF 10 FT."
Then it repeats the 10 foot boom length limitation note on the next page.
I saw the twisted remains of an overloaded HDBX48 tower not far from here a few
years ago. It wasn't pretty. I'm giving serious second thoughts about re-using
my HDBX48 at my new QTH, except maybe for some small 2-Meter yagis or a
10-Meter Ground Plane. As difficult as it is to climb, even with steel shank
boots, I may just go with something different.
LJ
-----Original Message-----
>From: Nick Pair <daweezil2003@yahoo.com>
>Sent: May 14, 2007 2:47 PM
>To: towertalk@contesting.com
>Subject: [TowerTalk] HBDX 48
>
>Thanks for ideas on getting this bugger down.
>I thought about the welding idea first since I am a certified welder on stick
>and MIG/TIG welding and have several welders around here(although none gas
>powered). The problem there is two fold. I can only get a edge weld on the two
>lapped legs which are just thin sheet metal and second the weld will make the
>metal brittle around the weld and could fail with a tubby guy like me (>6 ft
>and 300lbs) thirty two feet above the weld carrying gin pole and tools. Still
>this might be the most doable if I can get my much lighter son to do the
>climbing(he is not nearly as brave at heights as I am).
>I can't get a handle on the splint idea.The legs have two rather large bolts
>going through them at this height and the lower section has around a two inch
>taper offset just inches from the upper section overlap end.The closest I
>could get the angle iron on outside would take a 3/8 in shim and the inner
>over a inch to make contact with the legs. The unusual shape of the legs has
>presented many a problem to get around after the failure. If I can figure out
>how to get both bolts out on a leg at the same time and not have it come over
>on me I'll be able to easily splint it. The aluminum stop that keeps the leg
>from telescoping while you are erecting tower has sheared off when the bolt
>holes failed.
>I would really like to save the top 32 ft to recycle into a home brew hytower
>type vertical.
>The antenna on top is a six meter six element home brew on a 24 ft boom which
>has had a couple of elements fail due to vibration at the ubolt holes. Didn't
>put rope dampeners in them but learned a lesson and will do on next ones. I
>thought the vibration frequency would be to high to sustain at wind velocities
>we have here.(mother nature made a fool out of me again)
>
>I may have to weld it together to allow me to get bolts out to apply splint.
>Think that would work guys?
>
>Nick
>WB7PEK
>Dreaming of what I will be able to do with the soon to be empty 15,000 Lb base
>in sunny SW WA
>
>
>
>____________________________________________________________________________________Boardwalk
> for $500? In 2007? Ha! Play Monopoly Here and Now (it's updated for today's
>economy) at Yahoo! Games.
>http://get.games.yahoo.com/proddesc?gamekey=monopolyherenow
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