PRO TESTED IN CUSTOM-BUILT CIRCUITSee photo -- you are buying a factory matching pair of rare Made in Gt Britain 0B2 voltage regulator tubes, NOS NIB.
Factory matching codes on each tube. Clean tubes and clean boxes, highest quality inventory!
Each VR tube ("voltage regulator tube") has been PROPERLY tested in a custom-built VR tube tester, in which each tube is tested in an actual circuit to measure its ability to regulate the voltage across its entire operating range (5ma to 30ma).
Photos show each tube being tested for proper "nominal 108v" regulation -- the top digital meter is the regulated voltage and the bottom digital meter is the operating current through the circuit when the photo was taken, typically at the middle-to-upper end of the operating range. Since this is a REAL in-circuit test, each tube sold here is KNOWN to work PERFECTLY in a REAL circuit.[INV11]