> > damaged antenna off a straight mast rather than a bent one, but what
is the
> > difference in price you are willing to pay for that mast.
>
> Hold on a minute. The goal of ALL tower owners and manufacturers
should
> be to build a reliable tower/antenna system that is designed, engineered
and
> installed so that a minimum of maintenance is involved to provide ZERO
> mechanical failures. For YEARS.
Not me. Zero is a pretty extreme case!
Zero failures is a good goal for nuclear bomb detonators, but not my
stuff!
I balance cost with life, performance, and ease of installation.
> Please enlighten me how a 118K psi yield strength chromoly mast will
fail
> before a 35K psi 6061-T6 aluminum mast? When did they change the laws of
> physics? Wall thickness has little to do with it.
Then why does the rating include stress per square inch? Of course wall
thickness has a lot to do with it!
I used an aluminum mast for years. It was 6061-T6, and it was 18 feet out
of the tower holding a 5 element 20 meter yagi and a trap vertical right at
the top, some VHF stuff, and a 40 meter full size yagi.
A three inch 3/16 inch wall 18 foot aluminum mast sleeved over a 2-1/2 inch
24 foot 1/4 inch wall aluminum mast is pretty strong, isn't it? My friend
at Cleveland Tramrail said the Rohn 55 would fail long before the mast, and
he designed cranes for a living.
Now here's the question. Has anyone done a cost vs weight vs strength
analysis on aluminum and steel masts? I would think a simple analysis would
answer all questions factually.
Obviously aluminum WILL work quite well if it is large enough diameter and
thick enough wall. So what is the cost vs weight vs strength spread between
aluminum and steel, and where does the advantage shift from one material to
the other??
Logic please. Quell thy wicked lashing tongues and give me some facts.
73 Tom
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