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 Post subject: WTB: Hickok bias potentiometer
PostPosted: Jul Tue 10, 2018 10:46 pm 
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Joined: Nov Sun 22, 2015 9:07 pm
Posts: 569
Location: Chicago, IL
Greetings:

I am 16 and I just got my first Hickok 533 tube tester fully working. I had to make a case for it, get an 83 tube, and get a roll chart mechanism and install it. It cleaned up real nice. Unfortunately, the bias pot is bad. It has a "dead zone" below 10 on the dial but right at the end it comes back. And after 10 it works but then has trouble towards the middle, and looking at it I see the tapered end has come unwound partially and there are two spots in the wirewound coil that are broken and sticking out. The rest of it looks okay. It just bothers me since i've come this far with it and found out that the pot is bad.. I was looking forward to being able to use this as my main tester, so I hope someone has an extra pot. Thanks,

-Dylan, CT101


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 Post subject: Re: WTB: Hickok bias potentiometer
PostPosted: Jul Sun 15, 2018 3:40 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 5392
Location: 253 Blanche St. Plymouth, MI USA
First off, have you shot a good cleaner/lube into it?
Next, what is the value of the control and is it a carbon type or wirewound?

Mark Oppat
Antique Audio


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 Post subject: Re: WTB: Hickok bias potentiometer
PostPosted: Jul Sun 15, 2018 5:21 am 
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Joined: Nov Sun 22, 2015 9:07 pm
Posts: 569
Location: Chicago, IL
Hi Mark! There is nothing to lube as it's a wirewound pot and it's physically broken in two spots and unwinding at the end. It's a 3000 ohm specialty wirewound pot. It's special because it has a unique taper only made for these testers. I believe all bias pots are the same across any Hickok tester. I believe that's the only source for one is a junker tester unless someone could rebuild my pot. Here's more specs:

3000 ohms end to end
35% rotation 466 ohms
50% rotation 882.2 ohms
65% rotation 1583 ohms

-Dylan, CT101


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 Post subject: Re: WTB: Hickok bias potentiometer
PostPosted: Jul Sun 15, 2018 11:50 am 
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Joined: Nov Wed 30, 2016 7:35 pm
Posts: 2587
Location: Sunbury, Ohio 43074
You are correct in that this pot is, so far as is known, unique to Hickook... made just for their testers. I doubt you'll find one other than a donor from some other instrument. Unfortunately, it's a rather critical component as far as the accuracy of the tester is concerned.

I do not know that they are the same across all Hickok testers however; perhaps someone else will chime in on this. I'd tend to doubt it but it's possible.

If all else fails, wind one yourself :) Think of it as a learning experience... you're young!!. (myself, I think I no longer have the patience to start winding my own potentiometers lol.

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Preserving the history of electronics, one boat anchor at a time! :)
www.bbtvtestequipment.com


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 Post subject: Re: WTB: Hickok bias potentiometer
PostPosted: Jul Sun 15, 2018 12:54 pm 
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Joined: Aug Wed 26, 2009 1:45 am
Posts: 2503
Location: Sioux Falls, SD 57108
This is from a Hickok 6000. Not sure if it will work or not.

https://www.ebay.com/itm/HICKOK-VACUUM- ... Sw7P5bQjeW

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Don


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