Matched Pair Ken-Rad 6V6 6V6GT Vacuum Tubes Black Bottles NOS-Testing Magnoval but not in guitar amps

but not in guitar amps and other environments with loud noise and/or excessive vibration

There were no playback issues

probably from the second half of the 1920s

new in box Zenith 6ME8 tubes tested to spec on our Paul Hart-calibrated TV7/U

Matched Pair Ken-Rad 6V6 6V6GT Vacuum Tubes Black Bottles NOS-Testing Magnoval but not in guitar ampsThis new old stock testing matched pair of Ken Rad 6V6GT output tubes was tested on our Maxi Matcher 2 with 400 volts on the plates and a bias of 36 volts for shorts, gas and transconductance. There were no shorts or gas. Tube One drew 30. 5 milliamps' plate current and tested 2600 micromhos while Tube Two tested 31 3000. (New US made 6V6s typically test with plate current from the mid teens to mid 30s with transconductance from 2300 micromhos or so.)