[TowerTalk] mast.

giw at bellsouth.net giw at bellsouth.net
Fri Mar 19 21:18:26 EST 2004


I want to thank the many who responded directly to my request for information concerning the use of aluminum mast for my particular situation as described in my request. To summarize the responses, 1/3 said use only steel mast !!. 1/3 provided history of successful performance in the past with aluminum mast and 1/3 provided technical information that also helped me make a decision. Several included help and assistance in finding a source and their assistance is appreciated. The process  was a learning experience and a good one. For the 1/3 who were so adamant about using a steel mast I am sure they will think I did not learn much. 

I have purchased a new  2" X .25  6061-T6 mast to use as a 16 foot mast.  12 feet above the thrust bearing. The computer program winmarc says my configuration needs  more than 15878 in-lbs.in bending moment at 70mph and this mast provides 18800 in.lbs.  The difficult part was determining the force required to bend this particular mast. Not a large safety factor but enough considering that I don't think my guyed Rohn 25 tower with hazer will stand much more than 70 MPH winds. Weight was important to me so as to not overload the hazer and this drove my decision to an aluminum mast.  I look forward to getting up a 4 El Steppir at 70 feet and the rotatable dipole for 40 at 80 feet. The new antenna arrangement will be less total weight, and less total square footage than I now have up on a 10 foot steel mast. It has  been up for 10 years.  Not a world class instillation but one I think will be competitive when hooked to a PRO II and Alpha.  My thanks to towertalk for providing this great venue for assistance. 73 Van W4GIW


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