I used to sell lots of tubes on ebay back in the day and had Hickok and B&K tubes testers and all. I sold all the tubes and tube testers several years back. But I found a small stash of New Old Stock 12AU7A and one 6201 (an industrial grade 12AT7).
All tubes are sold. Thanks a lot!
Left to right:
Sylvania 12AU7A, USA, gray plates, halo getter on top, rough looking box - RCA 12AU7A, USA, gray plates, side getter, newer logo on tube, old style box. Box might be a replacement, or might be original - Westinghouse 12AU7A, USA, gray plates, halo getter, box a bit rough
Westinghouse 12AU7A, looks identical to other Westinghouse except labeled "Japan" instead of USA on the glass - "Western Union" 6201/12AT7
(6201 tube is sold), made by General Electric for Western Union, gray plates, halo getter, plain white box (torn flaps on box).
