Date: Wed, 9 Mar 2011 20:52:27 +0000 (UTC)
From: Eric Dobrowansky K2WD <k2wd@comcast.net>
Subject: Re: [TowerTalk] Mast Material
Wow,? I just ran some numbers thru this online utility, and the results vary
wildly from the older ARRL Antenna Mast Analyisis Excel sheet I found online a
year or so ago.
Can anyone tell me the correct stress PSI of the US Tower M20R reinforced
mast?? I would like to know the true ratings of this mast I have in use here at
the moment.?
Thanks
Eric
K2CB
## The US tower corp mast is made from 35 ksi material.... [ per their online
Q+A]. They have just stuffed one tube inside the other..and then but welded
em.
## IMO, if ur going to use steel.. use real steel. My mast is 2" OD x
.375" wall and is 107 ksi heat treated 4130 chromolly steel.
The ideal mast is 3" OD or 2.875" OD.. with a 1/4" thick wall..and at
least 87 ksi. A 2.875" OD mast + 1/4" wall weighs the SAME 7 lbs per
foot as
my 2" OD x .375" wall mast. Yet the section modulus of the 2.875" x
.25" wall tube is a helluva lot bigger than my 2" x .375" mast.
## In fact the 2.875" OD x .25" wall mast [ 87 ksi] is still stronger
than my 2" Od x .375" wall ,107 ksi mast..even though the yierld on the bigger
od mast is LESS.
## tashi towers sells 2" Od x .375" wall masts in 120,200 psi. The UST
version is only 107 ksi [ and a LOT more $$$] . Array solutions sells both
chromolly [ 104 ksi]
and 1026 dom masts [ 87 ksi] . Don't go cheap here, you will kick urself.
A good mast is a good investment...esp if you want to install more/bigger ants
down the road.
Later...... Jim VE7RF
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