Never used, perfect condition ordered directly from Mike Mathews at New Sensor. They were to be in a project that never happened.The matching #'s printed on the boxes are "50ma/4.8ma/v". Included is a paper with the detailed specifications, it is very thorough. They were produced to carefully match the characteristics, quote, "of the original Western Electric tubes. It's different than the Cetron or Chinese 300b" "Recommended operating conditions for the average WE and Sovtek 300B:
your tube current on the top of the box is measured under-
Plate voltage......300V
Cathode voltage....5VAC
Grid bias..........-61V
Maximum plate dissipation power not to exceed 40watts/tube. I will include new old stock unused USA CERAMIC sockets and sealed filament pots. USA gets free shipping, payments are usually paypal or check
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