My first guess was that the thrust bearing was not aligned correctly. As I
read furthur, it appears you are not running a thrust bearing. First and
foremost, a thrust bearing is recommended and will help to align the mast
correctly (if installed correctly).
The other issue is the rotor clamp. I've read here where you may need to
shim the clamp in order to get the mast centered.
My last question is, How far below the Rohn 25 "pointy top" is the rotor
mounted and is it LEVEL? I saw one installation where the rotor top was
less than an inch from the bottom of the top guide. No room for error
there! Drop the shelf down a level to give you more room for error.
Remember, the rotors are different. I wish I could better comment on the
center-to-center differences; but short of measuring them, I can't.
Let us know what you find!
>Yesterday afternoon, I replaced my old HAM-M with a HAM-IV recently returned
>from getting serviced.
>
>The M was showing some signs of age and it has been some years since it was
>last overhauled.
>
>On checking out the rotation of the new rotator on the tower, it swung from
>North through East to South. When swinging back the other way, rotation
>stopped at East. I was finally able 'ooch' the rotator through to about NNE
>where it resumed normal rotation speed. (The rotator worked perfectly on
>the test bench, by the way.)
>
>I moved the rotator back to South through East then back up to East where it
>stopped. I went up the tower (Rohn 25G, pointy top) to check things out.
>It looked like the mast was against one side of the bottom of the pointy top
>mast guide. When I had installed the rotator, I left the rotator base
>mounting bolts loose. I then tightened them up AFTER tightening the mast
>clamp--from something I read on the TT reflector.
>
>With the rotator on East, the rotator portion of the mast clamp is on the
>West side of the rotator where the mast seems to be tight against the pointy
>top guide. Is shimming the mast in the clamp a workable solution for this?
>
>If I shim it such that the mast now clears the bottom of the guide by a
>little bit where it's now binding, will I just move the binding point or
>will there likely be enough clearance between the mast and the guide to
>rotate freely? I didn't measure it, but it looks like there's about a
>3/16-1/4" of clearance on the other side of the mast from where it contacts
>the guide.
>
>Comments/Suggestions?
>
>Of course, today's weather forecast is thunderstorms, high winds, cooling
>temps.
>
>73,
>dale, kg5u
>
>
>
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>
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