Sylvania 5Y3 5Y3GT Vacuum Tube Rectifier Black Plate Pental Grid Cap It is probably a Mullard

It is probably a Mullard

They measured 23

Transconductance measured 44 for Tube One and 46 for Tube Two where minimum (65%) is 40 and 100% is 62

FOR EXAMPLE

It is a strange bird with well over an inch of space above the top mica spacer

Sylvania 5Y3 5Y3GT Vacuum Tube Rectifier Black Plate Pental Grid Cap It is probably a MullardThis Sylvania 5Y3GT black plate rectifier tube was tested on our Paul Hart calibrated TV7 U for shorts, gas and transconductance. There were no shorts or gas. It measured 54 53 where minimum (65%) is 40 40 and 100% is 62 62. This tube has a top D getter, short base; massive plates and an EG MHT date code. Im playing it now in one of my Radio Craftsman RC 2 mono blocks and it sounds great. WE HAVE SCORES OF THOUSANDS OF VACUUM TUBES. IF IT'S NOT