In a message dated 97-01-09 05:23:23 EST, you write:
>Has anyone had a failure with 2" x .25" 4130 chrome moly. If so, what
>did you have on your mast and what were the weather condz at the time of
Failures on a 4130? I've never heard of one. My mast is a 2" with
0.50" wall of a pedigree between 4130 and 1026 (I think it's about 80-90,000
psi tensile strength) and I've got over 100 feet of boom on it. The wind
doesn't stand a chance with it.
>Also, are there any opinions, pro and con, to using either a larger
>diameter and/or thicker wall? Or is
>it a function of the percentage of elements in the alloy? This would
>seem to be the logical explantion. I have found 2" x .25" 4130 with PSI
>ratings from 110,000 up to 168,000.
If you want a stronger mast, the bigger OD is the way to go; I'll let the
more engineering oriented TowerTalkians go over the reasoning and math.
>A number of years ago Stan, W7NI, had an excellent article in NCJ on
>masts. Does anyone remember what year and/or issues?
It just so happens that I have copies of Stan's article available for an
SASE. Send your request to TOWER TECH, Box 572, Woodinville, WA, 98072.
There is also an excellent exposition on masts in Dave Leeson's, W6NL
ex-W6QHS, book Physical Design of Yagi Antennas.
73, Steve K7LXC
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