Matched Pair RCA 6GU7 Vacuum Tubes NOS NIB RCA OSC 280 739 and F1 date

280 739 and F1 date codes

They have DC and BD date codes

Tube One measured 30 while Tube Two measured 32 where minimum (65%) is 22

100% is 56/56

Tubes Three and Four measured 2400/2650 and 2800/3200

Matched Pair RCA 6GU7 Vacuum Tubes NOS NIB RCA OSC 280 739 and F1 dateThis new old stock, new in box matched pair of RCA 6GU7 dual triodes was tested on our Jackson 648 Mutual Conductance tester for shorts, gas and transconductance. There were no shorts or gas. Transconductance measured 95% 100% for Tube One and 95% 105% for Tube Two. (New 6GU7s typically test from within a half standard deviation of 2000 micromhos and the Jackson expresses this in terms of a percentage.) I have played it in my Alan Eaton single ended