Matched Pair Tung-Sol 6K6 6K6GT Vacuum Tubes Black Glass 12Q7 Octal They have engraved / hot-stamped

They have engraved / hot-stamped bases on is Champion-branded and the other is Zenith

It has gray

This Sylvania milspec / industrial 5814 / 12AU7 / ECC82 dual triode was tested on our Paul Hart-calibrated TV7/U for shorts

This lot of four US-made black glass as well as gray glass number / type 57 tubes was tested on our Paul Hart-calibrated TV7/U for shorts

This quintet of Tung-Sol number / type 27 triodes was tested on our TV7 for shorts

Matched Pair Tung-Sol 6K6 6K6GT Vacuum Tubes Black Glass 12Q7 Octal They have engraved / hot-stampedThis matched pair of Tung Sol black glass 6K6GT tubes was tested on our Maxi Matcher tube tester with 325 volts on the plates and a bias of 36 volts. Tube One drew 26. 6 milliamps' plate current while Tube Two drew 27. 6. Transconductance was 1900 for Tube One and 1800 for Tube Two where new nominal is within one standard deviation of 1900. As I write, I am playing them in my Mini Mite 2013 and they sound great. WE HAVE SCORES OF THOUSANDS OF VACUUM