Date: Fri, 24 Jul 2015 20:04:47 +0000
From: Daniel Hileman <n9wx@hotmail.com>
To: TOWER TALK <towertalk@contesting.com>
Subject: [TowerTalk] Tower Installation Questions
Hi All,
I am thinking of going with an AN Wireless HD70 or 80...probably with a TH-11
Hy-gain at around 70' and a 3 element 40M Yagi @ 85'. This is all new to me,
and I am going to bring in people of experience (probably a crane to raise
tower and yagis), however, I do have a question about mast raising. How do you
winch or raise a mast from the top of the tower...say you install a yagi, then
want to hoist the mast up with the upper yagi? How is this done from the top of
the tower?
Thanks and 73,
Dan N9WX
## Do yourself a favour and use a 3 inch OD x .25 inch wall thickness, 4130
chromolly mast.
Typ they are 104-120 ksi yield strength.
Don’t even think about messing about with a 2 inch OD mast..even if its .375
inch wall thickness.
A 3 inch x .25 wall will weigh the same as a 2 in od x .375 wall, yet the 3
inch mast will be one helluva lot
stronger. You can see that effect on the arrl mast spread sheet.
The 3 inch od x .25 inch wall thickness mast, in heat treated 4130 CM is the
strongest thing there is.
the only mast stronger would be the same 3 inch od... but with a .375 inch wall.
## Then install mast steps. Then you can easily get to the top yagi. A 3 el
40m yagi will have its DE +
balun right at the mast, or very close to it. Then u don’t have to mess with
removing the rotor, and dropping the
mast down several feet..just to get at the top yagi. UST makes a mast raising
fixture designed
for their crank up towers, to raise and lower a mast.... pita. Even then,
you have to still loosen the boom
to mast clamps on the lower yagi, so the mast will drop down.
## mast steps are readily available that will easily do the job. Mine are
hb, and consist of 2 inch angle AL x.25 inch thick.
They are clamped to the mast with a single DX eng jumbo mast clamp, huge
surface area clamp. The top and sides of the angle
al are covered with that 2 inch wide x XXX long non skid stuff. At the
extreme ends, I use a single .25 x 20 SS bolt + SS nylock
etc. These small bolts protrude upwards....and used so you can feel them with
your climbing boots...so you know where the
ends of the mast steps are.
## climbing a mast is not difficult at all, but you have to be careful, and
proceed slowly, and use a pair of correct length lanyards.
Once at the top or whatever height up the mast you want to be at, one of the
lanyards is wrapped several times around the mast.
The 2 inch angle al is easy on the feet. Install the heaviest duty, bomb
proof balun etc, you can up there. Done right, you should
not have to be going up there very often...if at all.
Jim VE7RF
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