[TowerTalk] Rotator Choice for Larger Yagi

[Roger (K8RI) on TT]

Mine is the earlier version with the AC motor.  I don't know if the 
mechanical part of the new version has addressed the faults listed below 
or not.

I was using a PST61 on the array shown. 
http://www.rogerhalstead.com/ham_files/Tower29.htm . It worked fine 
except for the top seal design captured water causing the output shaft 
to rust which destroyed the seal letting water into the rotator.  A 
friend turned down the output shaft to get rid of the rust pits, so a 
slightly overs size seal worked just fine. That too is shown in the 
rebuilding link.

Beside the top seal design which can be worked around, I was made aware 
of the rotators main weakness being the bottom attachment to the mount 
being only 4 bolts shown in photo 21 in 
http://www.rogerhalstead.com/Gears.htm  Everything in the rotator is 
heavy duty (as shown in the rebuilding photos), "except" for those 4 
bolts.  I had no problems, but some others have had serious problems 
with large antennas.

The rotator is rated for 44 sq ft of antenna wind area, but I have my 
doubts as to those 4 bolts in that mount.
I like the way the PST61 works, but it does have a few short comings.  
OTOH, I think I'd go with the Alphaspid, or possibly the big (I think 
it's the PST71)  for the large antenna.

73 es good luck!

Roger (K8RI)


On 4/25/2016 Monday 3:14 PM, john at kk9a.com wrote:
> Nice antenna! I'm a big fan of prop pitch rotators.
>
> John KK9A
>
> To:	towertalk at contesting.com
> Subject:	[TowerTalk] Rotator Choice for Larger Yagi
> From:	Jerry Gardner <jerryw6uv at gmail.com>
> Date:	Mon, 25 Apr 2016 11:00:22 -0700
>
>
> Hi Tower Talkers
>
> I'm planning to replace the TH-7DX on my tower with an Optibeam OB17-4,
> which is a much larger antenna. I'm now looking at my options with regard
> to rotators beefy enough to handle this antenna (~27 sq. ft. wind area).
>
> Which of these would be sufficient to handle an OB17-4? Alfaspid RAK (the
> rotator currently on the tower), an Alfaspid Big RAK, or a Prosistel PST61.
> I don't need a controller as I already have a Green Heron RT-21.
>
> Thanks,
> Jerry
>
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>
>
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-- 

73

Roger (K8RI)


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