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Author Topic: shimming a t2x rotor  (Read 169 times)

W6AOA

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shimming a t2x rotor
« on: November 03, 2019, 09:20:03 AM »

This is new to me.  How is shimming done or is it needed.  I have a rohn 25g tower with a 1 1/2 inch mast with a bushing in the nosecone. Can anyone tell me what is involved in the "shimming" process ??
Thanks   
Ed Schaff  W6AOA  Pensacola, FL
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AA4PB

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Re: shimming a t2x rotor
« Reply #1 on: November 03, 2019, 10:37:12 AM »

You rotor manual should give you info about shimming the mast to ensure eccentrically with the top bushing or bearing. My HAM-IV manual gives the following info: "The geometry is such that a mast of 52mm (2.062 inches) will be exactly centered. For each 1.6mm (0.0625 inches) less mast diameter used, 0.8mm (0.031 inches) of shim must be wrapped around the mast of the clamping points.
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Bob  AA4PB
Garrisonville, VA

WB2WIK

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Re: shimming a t2x rotor
« Reply #2 on: November 12, 2019, 11:12:59 AM »

Or you can use four straight, flat shims installed 90 degrees apart around the mast where it clamps in the rotator housing; each shim would need to be 1/4" thick, so 1/4" thick flat aluminum or steel stock can work.

This keeps the mast rotating concentrically.   All the CDE ham radio rotators require shimming if a mast smaller diameter than 2-1/16" is used -- been that way for 5-6 decades.
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AA4PB

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Re: shimming a t2x rotor
« Reply #3 on: November 12, 2019, 01:01:34 PM »

Actually shims are only needed between the mast and the fixed portion of the mast clamp. The movable portion will tighten against the mast okay without shimming.
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Bob  AA4PB
Garrisonville, VA
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