[amsat-bb] Re: Mast strength??

Doug Faunt N6TQS +1-510-655-8604 faunt at panix.com
Thu Nov 22 11:46:22 PST 2007

If you don't get an answer here, try TowerTalk at contesting.com.
Or you can spend $10. here and do the calculations yourself.

73, doug

   Date: Thu, 22 Nov 2007 14:13:57 -0500
   From: "Stargate" <stargatesg1 at verizon.net>

   Hi all,

	   I am installing 20' of Rohn 45 with a flat top from Normsfab
   and a Yaesu GS-065 thrust bearing.

   The lower end of the tower is already figured out but I'm not sure of what
   strength 2" mast I need.

	   All this short tower will be supporting is a 3-4 element 6M homebrew beam
   just above the bearing on the tower,
   as well as, the elevation portion of the Yaesu G-5500 rotor with 8'
   fiberglass cross mast, and M2 2MCP22, and
   436CP42UG beams on each end of the cross boom.
   The 2MCP22 is 2.5 sq ft wind load.
   The 436CP42UG is 2.0 sq ft wind load.
   I'm not sure of the WL for the rotor and 6M beam.

	   The mast will have to be at least 18'-20' long to give 2-3 foot inside the
   tower to the AZ rotor and
   enough sticking out the top to give 1/4 wavelength (at 2M) spacing between
   the satellite antenna's
   and the 6M beam.
   The satellite antenna's are close to 20' long and mount from close to the
   center so I need at least
   10' (+1/4 wavelength) above the top of the 6M beam.

	   I'm not an engineering type so I thought I would ask on here. What
   and material would the mast need to be to support this.

   I am thinking T6061 aluminum, .25" thick wall, 2" outside diameter mast.

   I live in a 75mph wind zone.

   Any help would be much appreciated.


   A good friend will come and bail you out of jail,
   A TRUE friend will be sitting next to you saying.....


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