I've had a full size 3 element 40M beam in the air for the last 35 years, and a
pair of them since 1986 in a very exposed location. I've had no element
failures, apart from several elements failures during a microburst in 1993 with
winds estimated over 120 MPH (it severely damaged a dozen heavy duty Yagis).
I'm not sure if the failures was caused by the wind or by the aluminum siding
hanging from the elements (torn from a house 1/2 mile upstream).
My 40M elements start at 2 inch o.d. tubing at the center, with six concentric
layers of 0.058 inch wall tubing, gradually tapered to tips with 3/4 inch o.d.
x 0.058 wall. Each elements weighs approximately 75 pounds.
I can provide construction details for anyone interested in duplication this
heavy duty, ice and wind resistant construction.
---- Original message ----
>Date: Wed, 9 Aug 2006 23:33:50 -0400
>From: "W3TX" <firstname.lastname@example.org>
>Subject: [TowerTalk] M2 40M3FS element tip problem
>I have a full sized M2 40M3 yagi at 120ft. It's been up about 5 years. The
>distal element taper is aggressive, ending with a 3/8 inch diameter tip on
>each of the six elements. Too small in hindsight!
>The 3/8 inch element tips are failing (it appears from a vibrational
>mechanism). It's disconcerting tofind a 20 to 30cm section of aluminum with
>the mower blade :-)
>Q1). Has anyone else had this problem with the M2?
>Q2). Has anyone else modeled and/or implemented a less aggressive taper
>ending at 1/2 inch distal tips?
>Thanks in advance...
>73, Scott W3TX
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