Date: Thu, 6 May 2010 07:35:16 -0400
From: "D Calder" <towertalk@n4zkf.com>
Subject: Re: [TowerTalk] Loran Tower
http://www.n4zkf.com/files/Tower.jpg
Here is what happens. (the TV antenna in the foreground mounted to the
service drop isn't mine, it's my
idiot neighbor. It's 20 ft away it just doesn't look it in the pic)
If the A3S was mounted 2 inches above the tower instead of 2 feet, it
probably would have survived.
Doesn't matter, I don't use them anymore.
Dave n4zkf
## great pix. What was the mast made from?? What OD, what wall thickness
and what yield strength, alloy etc. I will add it to my broken /bent mast pix
collection. The last one I saw was of VE7SV's contest station.. and the
402CD
was mounted abt 8-10' above the tower. Huge windstorm.. and mast folded
at a 90 deg angle. Removing a bent mast is EXTREMELY DANGEROUS. In some
cases, a crane can't be brought in....to safely bring things down. Even with a
crane,
it's dicey. The correct mast is a helluva lot cheaper than replacing ants,
rotor's and
crane costs. Why spend $20K on ham gear.. then cheap out on a mast? The
mast is
the most important part of the entire project. The mast should be the last
thing that fails.
## The freebie ARRL mast software will tell you all you want to know.. and
uses the
latest EIA-222-F specs. Just plug in the OD of mast.. and wall thickness..
and the yield
strength in ksi. Then XXX square foot for each ant... and also exact height
up the mast
for each ant. Then enter a wind speed. The wind speed you enter is a moot
point, since the
software will tell you at exactly what wind speed it breaks at. What the
software WON'T
do, is tell you what happens with an ice load. + wind.
## BTW.. the local franchised 'metal supermarkets'... across USA /canada.. all
carry 1026
DOM tubing. It's all 75 ksi yield strength... and available in any OD.. and
a great number
of wall thickness's. They also sell 3 x diff kinds of zinc paint.. like ZNC,
galvcon, etc... in
both pint + gal containers.. and also spay bombs. Pour the stuff down the
inside of the tubing,
with both ends capped off,.. and teeter totter on a single saw horse.. rolling
it back and forth.
Then paint outside. It all has to be prepped 1st. That's a last resort, if
you can't get it hot
dipped galvanized locally. Array solutions also sells quality masts.. like
87 ksi 1026 DOM
but the shipping cost are not cheap.
## the right mast is still a lot cheaper than destroyed ant's. One of these
days, somebody is gonna
snap off a heavy mast... and on the way down it's going to take out
phillystran /polygon guy wires,
which have minimal shear strength..and there goes the tower as well.
Later........ Jim VE7RF
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