National Union NU 807 JAN-CNU-807 Vacuum Tube Milspec 6V4 Rectifier Transconductance measured a perfectly-balanced 2700/2700

Transconductance measured a perfectly-balanced 2700/2700 micromhos

This matched quad of new old stock-testing Sylvania 7B6 tubes tested 1033 micromhos for Tube One and 1050 for Tube Two on our Hickok 800

This nicely-matched pair of General Electric 12AU7/ECC82 dual triodes was tested on our Paul Hart-calibrated TV7/U for shorts

They have steel plates

new in box GE 12DB5 tubes tested to spec on our Paul Hart-calibrated TV7/U

National Union NU 807 JAN-CNU-807 Vacuum Tube Milspec 6V4 Rectifier Transconductance measured a perfectly-balanced 2700/2700This new old stock TESTING National Union 807 output tube was tested on our Maxi Matcher 2 for shorts, gas and transconductance with 400 volts on the plates and a bias of 48 volts. There were no shorts or gas. Plate current draw was 20 milliamps while transconductance measured 2450 micromhos. (New 807s typically test from the mid teens to mid 30s with transconductance from 2200 micromhos). I am playing it now in my Musical Paradise 301 MK 3 (with an