[TowerTalk] FW: Mast Wall Thickness

[Jim Thomson]

Date: Wed, 26 Feb 2014 10:37:31 -0500
From: john at kk9a.com
To: towertalk at contesting.com
Subject: Re: [TowerTalk] FW: Mast Wall Thickness

##  IMO,  whoever standardized a two inch mast was a complete idiot. 
A 3 inch  mast  with a .25 inch wall   weighs the same 7 lbs per foot as 
a  2 inch mast  with  a .375 inch wall.   The difference in strength is
HUGE in favour of the 3 inch mast.   Since they both weigh the same..they
also both cost the same.   Even a 2.875 mast with a .25 wall...made from 87 ksi
DOM tubing is ONE HELLUVA  lot stronger  than a 2.0 mast with a .375 wall...and made from
107 ksi  chromolly tubing. 
...
##  Just use the free  ARRL  mast software.   Then you can put any diameter mast and and wall thickness you want.
You can also enter any yield strength u want.    Then enter how much mast above the top of the tower...
and where the various yagis are placed on the mast.   It spits out the exact mph where it will break. 

##  the strongest mast, bar none I heard about.. used a 3 inch mast with a .375 wall....... made 
from 120 ksi  chromolly. 

Jim  VE7RF




I have not used a 2" mast in years.  At P40A I had two Yaesu G-2800DXA
rotators and my 2 1/2" aluminum mast fit into their clamp perfectly.  My
prop pitch rotators have 3" masts. I am sure that other rotators also
accept larger masts.

John KK9A