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What is this tube ?

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What is this tube ?

Post by philconerd on Fri Feb 20, 2009 5:16 pm

I have acquired a boxful of used tubes and I cannot identify what this tube is. It is a Sylvania 40A1, octal base. Anyone know what this one is? It is not listed in my RCA tube manual nor my tube tester chart.

G.

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Re: What is this tube ?

Post by geno on Fri Feb 20, 2009 5:24 pm

The 40A1 is a ballast/regulator tube.

Gene

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Re: What is this tube ?

Post by philconerd on Fri Feb 20, 2009 5:29 pm

Gene-
Thanks for the reply. None of my old radios use a ballast tube. So, I would probably sell this one if it is good. Anyone know how to test this ballast tube?

G.

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Re: What is this tube ?

Post by geno on Fri Feb 20, 2009 5:37 pm

For more info, that tube is used as a ballast tube in the cathode circuit of TV sweep tubes, such as the 6BQ6 tube. I don't know how to test it, as none of my testers have it listed.

Gene

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Re: What is this tube ?

Post by Don Cavey on Fri Feb 20, 2009 5:58 pm

What did the Motorola VT-71 set use? I have one of those sets and the ballast is missing...

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Re: What is this tube ?

Post by geno on Fri Feb 20, 2009 7:04 pm

Don, I don't have the Sams folder 55, but that is where the schematic is.

Gene

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Re: What is this tube ?

Post by easyrider8 on Sat Feb 21, 2009 3:20 am

Check for continuity on pins 2 and 7, if is has continuity it is good. Emerson used these tubes in their TV's. These sell for 5-10 dollars.

Dave

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Re: What is this tube ?

Post by philconerd on Sat Feb 21, 2009 12:41 pm

Thanks Dave-
Okay I checked continuity for pins 2 to 7 and I measure 135 ohms. If this is within spec, I should probably sell this one.

G.

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