This listing is a single National Union 01A vacuum tube. The 01-A or 01A is a storage battery triode used as a detector or amplifier. It is marked "Made in USA" on the glass. It has a sticker on the glass from Dan McGrew Radio Service in Bellingham, WA. The label shows a test date of 3/21/1937. 

I tested the tube on my TV-3B/U tester where the minimum test for a good tube is 460gm. This tube tested at 950. It will be reboxed for shipping.

 

I warrant the tube to be as described when you receive it. There is no additional warranty.

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