[TowerTalk] Re:Beam Orientation in Wind--How To Eliminate It.

[K7GCO@aol.com]

In a message dated 4/7/01 5:01:28 PM Pacific Daylight Time, n3rr@erols.com 
writes:
<< 
 Ford,
  Turn your beam so that it is "radiating" into the wind.  That's
 the least load on both the elements and the rotor.
 
 BTW, what melted?  Ice at the base of the tower?  What's your QTH?
 
 Bill, N3RR
 
 ----- Original Message -----
 From: Ford Peterson <ford@cmgate.com>
 To: <towertalk@contesting.com>
 Sent: Sunday, April 08, 2001 12:49 AM
 Subject: [TowerTalk] What a weekend!!!
  
 > About all I can do is sit at the window and worry.
 >
 > My 80' tower (68' rohn tiltover with 20' mast sticking 12 feet out of the
 > thrust bearing) is standing in over a foot of water, which just melted.
   The wx today is like nothing I've ever seen... 60+mph sustained winds most 
of
 > the day.  Gusts must be much higher.
 >
 > It looks like the tribander is holding up.  The 11el 2mtr beam at the top
    is whipping around like a flag on a pole.  I faced the beam into the wind
    last night in anticipation of today.  My guts keep telling me to turn it 
90
 > degrees from the wind to reduce the wind load.  I've been told that it is
 > easier on the beam/tower turned out of the wind but can damage the rotor.
 > The rotor is an alliance of some sort--ham fest special went up two years
 > ago in a very big hurry to beat old man winter...
 >
 > What's a fella to do?  Into the wind or out of the wind?
 > 
    Ford-N0FP
 > ford@cmgate.com
 >
 > Too bad 160 is lousy.  I'll bet the tower in a swamp would be a killer on
 > 160....

Ford:  Rotator design has been so deficient for many years that if you use 
what the mfgs recommend, you will be lucky to get 10 years out of it and do a 
lot of worrying.  One size larger may give you 20 years.  If you play the 
"orientation favor game" in the wind and/or use the BMW drive shaft cushion 
you might a get a few more years.  The ideal rotator is one the can take all 
the wind ice loads regardless of the orientation and without all kinds of "TT 
Band Aids" that are constantly recommended year after year.  A poorly 
designed tower, rotator & beam will cause you no end of grief, worry and 
money.  

I also prefer speeds faster than 1 RPM as I run a lot of antenna patterns and 
its great for quickly finding the true direction of a DX station even with 
low gain beams.  This concept is constantly bad mouthed by those who have 
never ever experienced or used a fast rotator or other recommendations and is 
a bad habit of some on TT.

There is a rotator that can handle the largest beams without all the "band 
aids" and concern for beam orientation in any wind.  I've used them for over 
55 years and have never had a mechanical break down.  They do have to be 
installed so that water cannot get into them or some bearings will rust.  
They are all replaceable except one and/or repairable.  They can be speeded 
up to as high as 6 RPM and handle a 3 element 20M beam with ease.  Bigger 
beams can be rotated at 2-3 RPM with great results.

It's called a "Prop Pitch Motor" off the W.W.II airplanes.  There are still 
many around and there are 3 major sizes.  The small one will handle say a 7 
element 10M beam with easy even speeded up to 3 RPM as I have done it.  The 
medium one will handle just about anything else.  It was my first one and 
it's still in use at 6 RPM.  There is a larger one which I haven't seen yet 
but am trying to get one for a use on a 2M beam--just kidding. 

When speeded up it "builds up" to speed and will torque the tower at the 
rotator point in proportion to the weight to the beam and speed.  Torque arms 
at the rotator are useful to reduce the torquing of the tower.  I always use 
a 20' mast 15' into the tower which lowers the torque point on the tower.  
When the large PP is revved up to 6 RPM with a 20M 3 element beam on it, it 
will coast for 90 degrees.  So the speed change is gradual building up and 
down.  In ham radio you have to learn how to design mechanically for whatever 
the stresses are or you may have a problem to fix in the winter time.

You do have to come up with a direction indication system using a selsyn and 
I have a very good and trouble free system.  I also have a rotating globe 
direction indicator with the top axis point centered on Seattle driven by the 
110V selsyn.  The smaller ones drive the compass needles just fine.  When I 
get time I will write it up for one of the mags.  

I keep hearing complaints repeated that when the PP is speeded up it will 
turn in the wind with the big beams like a 40M 3 element.  The turns ratio of 
the gears would drop from say around 6000/1 to say 2000/1.  You still have 
plenty to spare.  I've never had it happen with all the big beams I've used.  
I'm told it takes a couple of hours to do it in the wind.  My answer to that 
is "SO WHAT".  In doing so it does just what you would want of orienting the 
beam into a more favorable position to reduce the stress on the boom, tower 
and guy wires.  It automatically takes care of your concern.  What more could 
you ask?  There are those that would complain if hung with a new rope.  If 
the doesn't move and you are still worried about your beam in the wind, you 
have serious design deficiency problems that need to be corrected.  

If properly installed the PP will last you a life time of trouble free and 
"no worry service."  I'd recommend checking it over about every 50 years or 1 
average life time of use.  I paid $10 for my first one.  I just paid $50 for 
the medium PP and that's the highest I ever paid for all that I have.  I've 
been working it over and speeding it up.  It's pure mechanical joy working on 
these PP motors if you know how.  I have all kinds of pictures I've taken 
over the years of the various stages of assembly and conversions and may 
publish something on them.  It would be a difficult task for many without 
pictures and the necessary mechanical insights.  There is a trick of assembly 
that if not followed you will never get it together.  

I'd suggest going to the archives on PP motors and reading them and I have 
more info here.  Remember if properly installed, no "Band Aids" are needed 
and it will last a life time.  There is no Reflector for PP motors that I 
know of--it doesn't need any.  It's original speed with about 28VDC is 3/4 
RPM which is just too damn slow for "advanced beam use".  When speeded up 
mechanically it can be slowed down again just by lowering the voltage.  I've 
used a Variac on the PS to get the speed I wanted.  I've speeded up all the 
other light rotators I have and even the small TV rotators for many friends.  
They love the way they work.  Someday it may catch on.  You have to try it 
first.  I've spent the least money over 55 years for rotators, have had the 
least rotator problems of any ham (none) and the greatest utility and joy of 
use of anyone.  When you learn to select and use the right parts and 
components in ham radio, it will save you a lot of money and grief.  If you 
don't you will need a full time Reflector for info to solve your problems 
with one band aid or costly replacement after another.  Replacing a rotator 
is not an easy job.  This is regularly one of the biggest and most costly and 
time delaying problems in ham radio.  Design and select for longevity and no 
concern or worry for the wind speed.  None of the fancy mast bearings are 
needed--that often fail.  I use a simple aluminum surface to surface bearing 
I make that never rusts or fails.  Any PP motor you find today will have to 
be over hauled.  K7GCO  

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