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Antique Radio Technical Forum
UX201a Tubes.

Posted by Robert on 06/07/2012 19:25

:::Hi Robert
:::
::: I do it with low emission 201A's. Insert a tube in your tester and set filament to 6.3 volts. Leave the tube there without plate voltage for some time. It can take from minutes to hours. Usually 30 minutes will be enough. Works very well with RCA and Cunningham tubes. Not as well with some others.
:::
::: Filaments of theses tubes are Thoriated Tungston. In operation some Thorium burns off the surface. Heating the filament with higher voltage, 6.3 rather than 5, increases temperature and drives more Thorium to the surface.
:::
:::Norm
:
:Norm and Robert:
:We did that same thing with great, big, expensive transmitting tubes back in my transmitter days. I think we went 25% over the rated Voltage, for several hours, as I recall. Look up RCA 892R (radiator, made a water cooled tube air cooled) in a transmitting tube manual....interesting tube.
:Lewis
:
:
:::
:::Thanks Norm, I will give it a try. I have 5 of them to do.
:::
::::I was wondering if anyone has rejuvenated any of the RCA UX201a tubes and what is the best way?
::::
:::Good evening Norm and Lewis.
After 3 hours on 6.3 volts and I did measure with a Fluke 73, The tube has gone from 0 to 30 percent. This rate I might just save some tubes. I do have a question.
Does anyone have a list of other tubes that can be rejuvenated?
Robert.

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UX201a Tubes. 
Robert 06/06/2012 17:28 
Norm Leal 06/06/2012 17:39 
Robert 06/06/2012 17:45 
Lewis L. 06/06/2012 18:27 
Robert 06/07/2012 19:25 
Norm Leal 06/07/2012 23:04 
Robert 06/08/2012 19:22 
Norm Leal 06/08/2012 20:06 
george angel 06/09/2012 17:08 
Doug Criner 06/13/2012 09:49 
george angel 06/13/2012 23:17 

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