[TowerTalk] HBDX 48

Mon May 14 18:17:52 EDT 2007

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 at yahoo.com>
>Sent: May 14, 2007 2:47 PM
>To: towertalk at 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
>
>
>       
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