[TowerTalk] Rotator Choice for Larger Yagi

[Jim Thomson]

Date: Tue, 3 May 2016 16:47:28 -0400
From: "john at kk9a.com" <john at kk9a.com>
To: towertalk at contesting.com
Subject: Re: [TowerTalk] Rotator Choice for Larger Yagi

I am not even sure that torque means much. All of the rotator issues that
I have had (broken gears, worn keyways, failed potentiometers, etc)
occured while the station was QRT.

I currently use a small and a medium prop pitch.  The small has a 9576:1
gear ratio and the medium has a 7063:1 ratio.  It is possible that the
small one has the same or more torque than the medium.  Which one is less
likely to break, I would guess the medium.  I think you would be happy
switching to prop pitch rotator and Green Heron controller.

John KK9A

##  A  buddy had the monsterstepIR,  turned by an OR-2800....and it lasted
exactly 9 days !    2 other folks  with the exact same ant / rotor combo  had
similar results.

##  If I remember correctly, the small prop pitch had its final gear  driven in 
3 x places,  every 120 degs, by small gears.   The OR-2800 has its  final gear
driven by only one small gear.   By using 3 x small gears, the back lash is
distributed over 3 gears.....and not just one.  

##  Back in the late 70s, early 80s, a japanese rotor maker had a rotor out that
used from  1-4 external, bolted on motors, every 90 degs around the perimeter
of the motor.   You could buy it initially  with 1 motor, then add more, if you required
more tq..and less back lash. 

##  I currently have  1  OR-2800 left..and its  final small gear is chewed up / trashed.
Back in the late 70s, early 80s,  I sold my ham-4  to a buddy, who used it to turn a 
hb 6-el 10m yagi on a 36 ft boom.  He always kept it pointed in one direction 99%
of the time. Eventually, due to constant wind buffeting, it literally ate 1-2 teeth, completely
gone. 

## perhaps what needs to be done is to use a worm gear to drive the final gear,  that would
eliminate the back lash, +  provide more surface area.  That and /or use a better grade of steel.
and /or  thicker gear teeth.   Or  provide some form of isolation  between mast + rotor.

Jim  VE7RF