Matched Pair CBS Hytron 12SN7 12SN7GT Vacuum Tubes Black T Plates Number 1 In F Major This matched trio of RCA

This matched trio of RCA 6BY5GA tubes were tested on our Paul Hart-calibrated TV7/U for shorts

The diodes measured 78 and 74

Transconductance measured a nicely-balanced 92/95 where minimum (65%) is 56/56 and 100% is 87/87

Please note Tube Two’s centering pin is missing

Matched Pair CBS Hytron 12SN7 12SN7GT Vacuum Tubes Black T Plates Number 1 In F Major This matched trio of RCAThis matched pair of CBS Hytron 12SN7GT dual triodes was tested on our Paul Hart calibrated TV7 U for shorts, gas and transconductance. There were no shorts or gas. Transconductance measured 75 70 for Tube One and 77 72 for Tube Two where minimum (65%) is 50 50 and 100% is 77 77. They have black T plates; D getters; steel support rods; excised chevrons in their top mica spacers as well as 210 5439 and 5413 provenance date codes, respectively. I have