For sale is a copy of the original documentation set for the Micronta 22-012 General Purpose Tube Tester. Included are the instructions and a tube test data chart. To the best of my knowledge, there were no updates ever published to this chart. I don\'t think you\'ll need one because this tube chart is as complete as I\'ve seen. It even has many \"modern\" tubes including Compactron and Novar horizontal sweep output tubes that were often used in ham transmitters and CB linear RF amps.This copy is from vintage books and has a few marks and underlines. None of these marks interfere with legibility.Also included are a couple schematics that detail the operation of this tester. The Micronta 22-012 design is based on an older tube tester from a different company. I provide a schematic of the precursor tester with component values changed to more closely match the 22-012 unit. I also provide notes on this schematic to detail differences between the Mictronta and the base unit plus Micronta as-built variations you might encounter. The main difference between the Micronta and the precursor tester is in the switch circuitry. To explain those differences, I provide a drawing of the switch details. If you sort of, kind of know what you\'re doing, you will have everything you need to fix your Micronta tester.Let me know if you have any questions.

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