Rohn hdbx-48 - towertalk Forum at eHam.net

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eHam.net Forum : towertalk : Rohn hdbx-48

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Rohn hdbx-48	Reply
by KB3LFD on May 4, 2006	Mail this to a friend!
Hello all! I have a new rohn-hdbx-48 tower that is not yet up. This is a self supporting tower. I know that Rohn does not recomend using any antennas with a boom longer than 10 feet. However i would very much like to put a Hy-Gain 6meter model 66dx on it as well as a as yet undetermined smaller 2meter boom above the 6meter antena. The 6meter antenna has a 24 foot 5 inch boom and the longest element is 9 foot 9 inches. Hy-gain says the 66dx is 1.8 sq ft surface area with a wind load of 46.1 lbs @ 80 mph. It weighs only 17lbs. The effective moment is 213 foot lbs. I would keep the 6meter antenna low on the mast, just a little above the top of the tower. The rotor will be an alliance HD-73-1. I do not plan on using a 2meter beam nearly as large. Any thoughts pro/con are much appreicated!! Thanks Doug kb3lfd

RE: Rohn hdbx-48	Reply
by WB2WIK on May 4, 2006	Mail this to a friend!
If you don't have engineering review of your installation by a building and safety inspector, obviously you can do whatever you want. The HDBX48 is rated only for short booms because of its design and construction, which uses rivets and hardware, rather than welds, and cannot take a lot of twisting (torque) stress. That stress mostly occurs from stopping long antennas, not from winds. The HD-73 doesn't have a brake that can stop the 6L 6m beam quickly, so this may not be much of a problem; however you might wear out the rotor with the 24' long antenna (HD-73 is kind of a "medium duty" rotator, and I know I've certainly worn a few out). Having used the HDBX towers many times at different locations, I'd say you're probably okay; however if you have to undergo an inspection and provide documentation that you're not exceeding any ratings, you'd be in trouble because obviously you are. WB2WIK/6

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