Matched Pair RCA 12B4 12B4A Vacuum Tubes Valves Black Plates Copper Support Rods NOS-Testing 7 Lot Of Seven Transconductance was 1900 for Tube

Transconductance was 1900 for Tube One and 1800 for Tube Two where new/nominal is within one standard deviation of 1900

new in box Sylvania 12AV7 dual triode was tested on our Paul Hart-calibrated TV7/U for shorts

but also because if it is a brand other than RCA

Tube One measured 40/44 while Tube Two measured 42/46 where minimum (65%) is 25/25 and 100% is 38

Matched Pair RCA 12B4 12B4A Vacuum Tubes Valves Black Plates Copper Support Rods NOS-Testing 7 Lot Of Seven Transconductance was 1900 for TubeThis new old stock testing matched pair of RCA 12B4 tubes was tested on our Paul Hart calibrated TV7 U for shorts, gas and transconductance. There were no shorts or gas. Tube One (12B4, harp getter with sheet) measured 44 while Tube Two (12B4A, O getter) measured 46 where minimum (65%) is 32 and 100% is 49. Wish I could tell you how they sound, but I don't have any equipment that uses these. WE HAVE SCORES OF THOUSANDS OF VACUUM TUBES. IF IT'S NOT