Sylvania 5U4 5U4G Vacuum Tube Rectifier Black Plate Shoulder ST Variety Sylvania Octal new in box US-made 6F7

new in box US-made 6F7 tubes tested to spec on our Paul Hart-calibrated TV7/U

new in box RCA 6AB7 tubes tested to spec on our Paul Hart-calibrated TV7/U

but I do not recommend using them at any other filament voltage than 12

This hardcover book is in good condition

Sylvania 5U4 5U4G Vacuum Tube Rectifier Black Plate Shoulder ST Variety Sylvania Octal new in box US-made 6F7This Sylvania 5U4G rectifier tube was tested on our Paul Hart calibrated TV7 U for shorts, gas and emissions. There were no shorts or gas. It measured 52 54 where minimum (65%) is 40 40 and 100% is 62 62. This tube has 139 date codes, a bottom, D getter and nice flashing. WE HAVE SCORES OF THOUSANDS OF VACUUM TUBES. IF IT'S NOT LISTED, WE MAY HAVE IT. PLEASE ALSO SEE OUT ETSY SISTER SITE "LOWTECHTWOO" AND OR CALL OR TEXT US AT 202 372 6931 IF YOU DO