[TowerTalk] (no subject)

[K7GCO@aol.com]

In a message dated 8/18/00 9:04:04 PM Pacific Daylight Time, 
107770.3462@compuserve.com writes:
<< 
 Just a couple more cents to throw in, would it be possible to pin the mast
 but use a bolt or whatever that would ultimately shear before too much
 stress was put on the rotor?  Not sure how that could be determined but it
 could be a mechanical fuse to keep from really tearing things up
 I recall once trying to pin a mast for no rotation and it was fairly easy
 to shear it off without too much force.
 
 73 Jim KI7Y
  >>
   There are times when "Johnson Mechanical Band Aids" are needed to solve a 
problem.and we all do this at times until we find the final solution.  
Sometimes the band aids are so good no further change is needed.  Others 
eventually fail to the point where users and even manufacturers say "that's 
it and develop or look for the final fix."  Then even proven designs fail as 
ways are found to ruin them.  Firestone comes to mind.  In some areas like 
rotators and towers this point has not been reached as yet.  Tolerance, time 
and money to waste for bad designs still exists with no sign of a solution 
innsight..  Manufactures of certain ham gear or antennas seems to hindge at 
the level where Reflectors like TT are needed to cover all the band aids and 
few permanent fixes are ever made even well into the year of 2000.  

At the age of 69 I don't have any tolerance, time or money to waste and that 
tends to govern my suggestions hoping to speed up the time when others decide 
they are damn tired of "Just Plain Junk".  Paul Harvey summed it up saying 
"We live in a "Junk Society".  We have junk cars, junk houses, junk food, 
junk pills, junk schools, junk books, junk buildings, junk movies, junk TV's, 
junk TV programs, junk radios (antennas, rotator, towers)(the old radio 
programs are absolutely great) and some cities even have junk people.  They 
have more suicides than homicides.  There is even junk sex also--it's low in 
emotional nutrition..  Yet the largest profits are somehow still made--on 
Just Plain Junk.  

Now this is the year 2000 and "certain problems" have been around since the 
first yagi was installed over 70 years ago.  Inadequate rotators or any 
device usually takes awhile to work out the bugs and many "final designs" 
still continue to be very elusive and no solution or demand of one has shown 
any flicker of light of ever emerging.  Occasionally suggestion are made by 
those who have solved the problem--over 50 years ago and repeatedly since.

"To Shear or Not To Shear" is the latest pin mast rotator problem plauging 
many hams minds on TT today still in the year 2000.  Others even adjust the 
tension on clam plates to make sure the casting don't eventually crack or the 
mast can slip before damage to the rotator or even the beam in a high wind.  
It's kind of a "mechanical fuse."  No one has yet to suggest a design that 
doesn't need all these band aids.  I'd like to see an add "Band Aid Free" for 
a product in the rotator, tower and antenna area.

At the Dayton Antenna Forum there was a "wind balancing concept" with an 
additonal short element placed the right spot to "wind balance the antenna" 
from any direction.  That should reduce wind torque surges on the mast and 
rototor.  That's a good idea that I don't even call a band aid as it corrects 
a built in deficiency..

Another band aid on TT was to use a very long mast of about 40' into the 
tower to take up some rotational torque peaks.

Another is the "BMW cushion" used inbetween the motor and rear transmision.  
My Porsche doesn't need it.  They strengthened everything adequately the 
motor drives.  It's used between the rotator and the mast and does have some 
value but it is another band aid. 

Then there are all the "brake problems" that go on and on and on.

Are you aware nany never ever have all these problems.  They use a rotator 1 
to 2 steps larger on purpose than the maunfacturer recommends--spend the 
money.  Or they have Prop-Pitch Motors properly installed as they are the 
only roator that is Band Aid Free.  There are basically 2 sizes (a 3rd really 
big one exists) that fit all beams.  If properly installed they seldom ever 
require maintenance except motor brushes after say 50 years or 2 owners full 
time use.  All my brushes are still good after 55 years use.  Water got in 
one that I didn't install properly but I've learned how to keep the water out 
and replace or repair all the bearings.  One bearing is no longer available.  
It's a good idea to remove the original oil in it and replace with a low 
temperature grease.  The oil will slip by the bottom seal and get into the 
motor.  Ne seals are available at the top.

PP motors have a 3/4 RPM with 28 VDC.  They will even work with AC voltage 
but at a lower speed and higher brush and comutator wear.  3 methods have 
been developed to mechanically speed them up without any mechanical 
compromises as they can have up to a 9000/1 gear ratio.  I have a PP motor on 
a 2M beam for the speed of rotation.  The first speed up in CQ in about 1946 
should not be used other than on light beams.  The 2nd modification shortly 
after is great.  I came up with one that is the simplest of all and it can be 
returned to normal if ever desired where the 2nd mod cannot.  Once the faster 
speeds are used I know of no one who ever went back to 3/4 or less RPM--maybe 
for a 75M beam.  Due to the very high initial gear ratio even after a speed 
up, NO BRAKE IS NEEDED.  The only thing that can happen when it is 
mechanically speeded up is that all those who have never used a PP motor 
claim is "it can rotate over a period of time to an orientation with less 
wind stress with a wind unbalanced 40M beam".   Big deal!  These hams would 
complain if hung with a brand new rope.  This is actually a "desired 
characteristic" for when one has a 40M wind unbalanced antenna--for those who 
can't see the light. This reduces the mast/tower torque and guy wire 
stresses.     

With a full 28VDC on them I can get up to 6 RPM.  When I tell other hams of 
this I hear the total nonsence again "it too fast-it will tear up the tower 
or bream."  For 10M and higher "it's perfect."  I've even use it on a 3 
element 20M beam on a 24' boom with a long mast in a 20' tower.  The PP motor 
was near the bottom where it removed 95% of the tower from the additional 
rotational torque.  On a high tower, rotational torque on the tower can be 
reduced with guy torque arms that are available.  To further explain why 
speeds above 1 RPM are desirable and very practical, the turning rate 
accelerates up to the full speed over say 5-25 degrees (1-6 RPM) due to the 
high gear ratio and momentum of the large PP.  With the larger PP (actually 
the meduim one), it would smoothly coast down to a stop from say 6 RPM over 
about 90 degrees--less with slower speeds and the smaller PP.  There are "no 
sudden jerks."  You learn to shut it off before you get there.  This is a 
great rotator concept.  I used to do a lot of F/B checks and loved the speed. 
 I can peak an unknown signal except with a 2 element all band quad with the 
DE's tied togther with a real fast or I can nail a known DX station with the 
same antenna with individually fed DE's when I hear him real fast.  Those who 
I demonstrate this to inparticular with a higher gain beam "suddenly see the 
light--or speed light" and demand I convert their PP motors or get them if 
they don't have them.  

One can adjust the speed to the size of the beam.  For example a 7 element 
10M beam on a 44' boom, I usually rotated at 3 RPM and will use 5-6 RPM with 
a proper tower torque measures on the tower below the rotator.  

I have a way to easily speed up conventional rotators also.   I increase the 
diameter of the small gear on the motor shaft and decreased the size of the 
adjoining gear of such ratios to get any new rpm I want.  The same shaft to 
shaft spacing remaines.  I frequently use a smaller beam than what it was 
designed for and have yet to have a problem.   I even speed up the small TV 
rotators the same way.  4 RPM for even a large TV antenna is no problem.  

I did add a great feature of a "stepped voltage switch."  This is not needed 
for PP rotoar protection.  I do use a variac to adjust the initial working 
voltage and speed.  The voltage steps were such that I obtained speed 
increments of for say a 3 RPM max of 1, 2 or 3---then 3, 2, 1 and 0 RPM per 
step.  So regardless of the final speed, no more than 1 RPM increase or 
decrease ever occured depending on how fast I rotated the stepped swtich CW 
or CCW.  I could stop at any speed or change it as desired for "fine 
turning."  It works like a charm and speeds up all phases of antenna pattern 
measurements and general ham operation.  One DXer who used mine had all his 
rotators speeded up with the proper design and is trouble free to this 
day--and very fast.  Manufactures probably won't do this as it would add some 
additional cost to them but it would be a great sales feature for an 
innovative manufacturer.  Does one exist?  

You can still use an "advanced rotator design 55 year old PP rotator" from 
the last Century with the proper modifications.  M Squared has a kit for 
proper installation including a direction indicator.  If made today the PP 
motor would problably cost $4-5000.  The mechanical tolerance control inside 
was tremendous during WWII manufacture.  I've never seen any variance in the 
fit of all the parts and bearings.  It's the only mechanical device I've 
worked on where this was true.  Quality control of mechanical tolerances 
vanished from US manufacturing for many years but was found again in Japan 
aided by Demming and his efforts.  US manufcturers wouldn't listen to him 
after the WWII as the US could sell anything it made.  I believe the PP 
motors were made by Electrolux the Vaccum Sweeper Co and I still have one of 
their Sweepers.  Does anyone have any manufacting plans for the PP motor or 
any other background?  I love these rotators.  I used to know the son of the 
owner of Electrolux in Philadelphia back in the 60's--Walter Groff.  He had 
an interest in guns.  I didn't know then of this connection if my information 
is correct.

If you ever take one apart and remove the planatary gear, there is a trick 
you have to know or you won't get the bell gear to mesh.  There are some 
witness marks on the 3 or 4 grear planatary gear like a "0" that have to be 
all pointing out.  Some of the 4 gear models that have 2 marked with a "0" 
and 2 with a "2".  Which do you use--the "0" or the "2" all pointing 
out--neither?  You have to alternate these and I had to find this out the 
hard way.  I accidently did it right the first time not knowing what I did.  
Years later I speeded up the motor and could not get the bell gear on with 
either combo.  How did I get it together before on the first try--blind luck. 
 So as a last try I alternated them and presto--it dropped in place.

By the way there are no Band Aid Reflectors for PP motors and other properly 
made antennas like the M Squared ones I've used, Antenna Mart Quads and 
Raibeams--they don't need any.  When you get the ham license it doesn't tell 
you that beam antennas can grow into an Albatross on your back or actually 
your tower if not properly installed, cost you a lot of maintenance time and 
money if it's not of the proper design.  Hams incorrectly assume many of them 
will never need any maintenace.  Many antenna problems never get fixed over 
the winter.  Those with big contest antenna sites can spend a lot of time 
working on them.  Check into the Band Aid List on TT often needed of 
equipment before you buy it.  It will cost you more than the money you think 
you saved buying it.  k7gco

.               



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