Matched Quad General Electric GE 6SN7 6SN7GTB Vacuum Tubes Copper Support Rods Octal Metal Base OM 59 60 and 64 where

59 60 and 64 where minimum (65%) is 40

They are a tad microphonic and are fine for home use

62/35 and 74/56 where minimum (65%) is 50/50 and 100% is 77/77

This (most likely) Sylvania-MANUFACTURED Wizard-BRANDED number / type 80 rectifier tube was tested on our Paul Hart-calibrated TV7/U

well-mastered

Matched Quad General Electric GE 6SN7 6SN7GTB Vacuum Tubes Copper Support Rods Octal Metal Base OM 59 60 and 64 whereThis matched quad of GE 6SN7GTB dual triodes was tested on our Paul Hart calibrated TV7 U for shorts, gas and transconductance. There were no shorts or gas. Transconductance measured 56 56 for Tube One and 58 61 for Tube Two. Tubes Three and Four measured 58 61 and 60 62, respectively. (Minimum (65%) is 50 50.) They have horse shoe getters; copper support rods; great flashing and 60 13 188 5, 56 39 188 5, 59 13 188 5 and 57 26 188 5 date factory