Matched Quad Sylvania 7A7 Vacuum Tubes Valves NOS-Testing Lot Of Four 6AL7GT Octal T08 These four US-made 6SF7 tubes

These four US-made 6SF7 tubes were tested on our Paul Hart-calibrated TV7/U for shorts

This happens perhaps once -- maybe twice -- per decade

One is a 1P21 while the other could not be identified

Etsy will indicate the quantity remaining

Matched Quad Sylvania 7A7 Vacuum Tubes Valves NOS-Testing Lot Of Four 6AL7GT Octal T08 These four US-made 6SF7 tubesThis new old stock testing matched quad of Sylvania 7A7 tubes was tested on our Hickok 800 and all measured 1900 micromhos where new nominal is 2000 and minimum (65%) is 1300. 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 NOT SEE WHAT YOU NEED OR HAVE ANY QUESTIONS. 1. MOST OF THE TUBES WE SELL ARE OVER 70 YEARS OLD.