General Electric GE 12AT7 ECC81 6679 Vacuum Tube Premium NOS NIB Hot-Stamped Bases These tubes have steel support

These tubes have steel support rods and top

It is probably a Mullard

6 milliamps/2150 micromhos and 18

These 11 RCA gray glass 6D6 tubes were tested on our Paul Hart-calibrated TV7/U for shorts

General Electric GE 12AT7 ECC81 6679 Vacuum Tube Premium NOS NIB Hot-Stamped Bases These tubes have steel supportThis new old stock, new in box industrial grade GE 6679 12AT7 dual triode was tested on my Hickok 600A for shorts, gas and transconductance. There were no shorts or gas. Transconductance measured 4100 3400 micromhos. (New 6679s typically test within 1. 5 standard deviation of 4000 micromhos; minimum (65%) is 2600). It has gray, wing plates; a top, slant D getter and excellent flashing. I am playing them in my Bottlehead Crack headphone amplifier as I