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Author Topic: Knobs for large variac  (Read 241 times)

WB8PFZ

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Knobs for large variac
« on: July 01, 2022, 04:40:09 AM »

I am looking for a few large knobs for some General Radio variacs. Does anyone know of a source? The center hole is .750 diameter. Thanks Mike
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K4JJL

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Re: Knobs for large variac
« Reply #1 on: July 01, 2022, 04:53:06 AM »

A motor pulley for a 3/4" shaft would work.  Might look a little weird, though, but it would work.
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W1RKW

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Re: Knobs for large variac
« Reply #2 on: July 01, 2022, 05:16:53 AM »

I am looking for a few large knobs for some General Radio variacs. Does anyone know of a source? The center hole is .750 diameter. Thanks Mike

https://www.ebay.com/itm/194869184540?hash=item2d5f1bc81c:g:FCsAAOSwv7JiFsxI
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WB8PFZ

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Re: Knobs for large variac
« Reply #3 on: July 01, 2022, 06:01:05 AM »

Thanks for the Ebay link.  Need to get a loan :)
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K8AXW

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Re: Knobs for large variac
« Reply #4 on: July 01, 2022, 08:47:03 AM »

Re: eBay link:  I suggest "Make an Offer."
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A Pessimist is Never Disappointed!

N1BNC

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Re: Knobs for large variac
« Reply #5 on: July 01, 2022, 09:41:35 AM »

How about a small steering wheel?
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KG4RUL

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Re: Knobs for large variac
« Reply #6 on: July 01, 2022, 10:15:15 AM »

If you use a metal (conductive) knob, be sure to check for stray voltage from the rotor shaft to the case.  You wouldn't want to have an electrifying experience.
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KE6SLS

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Re: Knobs for large variac
« Reply #7 on: July 01, 2022, 10:28:49 AM »

A motor pulley for a 3/4" shaft would work.  Might look a little weird, though, but it would work.

Make sure you keep your other hand on the test gear so you can fully appreciate the electrocution.  sigh

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WB8PFZ

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Re: Knobs for large variac
« Reply #8 on: July 01, 2022, 10:32:28 AM »

The 3/4 inch shaft is insulated. It looks like a steel core with a plastic outer cover. Kinda like a M & M
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WA3SKN

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Re: Knobs for large variac
« Reply #9 on: July 01, 2022, 11:53:35 AM »

.75 is a fairly common size.  I would look at CPVC and PVC plastic pipe "T"s to see how snug they fit.  You might have to add some glue or a set screw.

-Mike.
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KG4RUL

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Re: Knobs for large variac
« Reply #10 on: July 03, 2022, 01:46:52 PM »

The 3/4 inch shaft is insulated. It looks like a steel core with a plastic outer cover. Kinda like a M & M

If you use a metal knob with a setscrew, make sure it doesn't go through the plastic insulation.
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WB8PFZ

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Re: Knobs for large variac
« Reply #11 on: July 04, 2022, 04:07:40 AM »

Correct.
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N8YX

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Re: Knobs for large variac
« Reply #12 on: July 04, 2022, 12:18:08 PM »

Go for broke.

Put a ship's wheel on the thing and watch the conversations start.
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