Think about it... ham rotator speed typical @ 1 RPM
Bearing requirement - minimal... bearings with ball bearing races are
nice but the reality of the ham antenna is it just don't do that much
turning... other than possibly the guys who track satellites your
typical ham just does not use the rotor THAT much!
As long as the mast is not binding in that upper pointy top it will be
fine... one local has three 199 foot towers and side mounted yagis up
and down all of them - these side mounted antennas have a mast pipe that
passes from the rotor through a PVC sleeve for a bearing... its a loose
fit, that's it!
This is one of those times when hams can get over zealous - I am guilty
of it with two masts that have both a top and an intermediate TB... the
intermediate one could have been a piece of thick plastic with a 2 1/16"
hole in it for what it does!
If your mast is chafing on the pointy top tube then you need to check
the location of the rotor in relation to the hole - as has been
mentioned on this reflector many times the goal is for the rotor to end
up centered on where the mast wants to be. You do not want to force the
mast pipe to match the rotor's location. Typically this is done by
working backwards from the mast, first tightening the mast clamps on the
rotor then the bolts for the bottom of the rotor to the plate and
finally the u-bolts that clamp the rotor plate to the tower legs. by
working in this order you are least likely to cause a situation where
you encourage binding of the mast in the pointy top. If you still have
a situation where there is binding care should be taken to figure out
why... it is possible the pointy top was smacked during shipping and is
out of plumb with the rest of the section.
Low RPMs and hardly ever a complete rotation are pretty typical for a
ham rotor... here in Florida most of my rotorS only swing between Europe
and Hawaii or about 120 degrees (1/4 of a full rotation). YHMV (your
headings may vary!)
19 Days until the Florida QSO Party - all 67 Florida Counties WILL be on
the air... check out the details at:
Jerry K3BZ wrote:
> I've received several good comments and ideas, thanks. What I'm really
> concerned about is the aluminum mast and the aluminum tower sleeve wearing
> away slowly from metal-to-metal contact. But grease isn't the only way to
> keep them from actually touching. What about some sort of "bushing" to fit
> between the mast and the sleeve?
> I was thinking of a section of thin-wall pvc of appropriate diameter and
> wall thickness, sliced length-wise and inserted betwen the mast and sleeve
> on opposite sides of the mast, then clamped to the mast above and below the
> sleeve. The idea would be for the pvc to be sacrificed and replaced every
> few years as necessary. I'm no engineer and I don't even play one on TV, so
> any comments from those more talented than I?
> Jerry K3BZ
> See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless
> Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any
> questions and ask for Sherman, W2FLA.
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