Sylvania 5U4 5U4GB Vacuum Tube Rectifier Black Plate Nine Eleven a thimble getter and excellent

a thimble getter and excellent flashing

58 and 71 where minimum (65%) is 50

Transconductance measured 72 for Tube One and 76 for Tube Two where minimum (65%) is 58

but I glued it anyway

new in box GE 22JR6 tubes tested to spec on our on our Jackson 648

Sylvania 5U4 5U4GB Vacuum Tube Rectifier Black Plate Nine Eleven a thimble getter and excellentThis black plate Sylvania 5U4GB rectifier tube tested 52 48 in Sections One and Two, respectively, on our Paul Hart calibrated TV7 U where minimum (65%) is 40 40 and 100% is 62 62. It has a top O getter; a crenelated top mica spacer; black plates and jd AED date codes. THIS TUBE'S CENTERING PIN IS MISSING AND IT HAS BEEN MARKED FOR SAFE AND EASY INSERTION. THERE IS A CLOSE UP PHOTO OF THE BASE TO SERVE AS A REMINDER. WE HAVE SCORES OF THOUSANDS OF