Matched Pair RCA 6GU7 Vacuum Tubes NOS NIB RCA OSC

Matched Pair RCA 6GU7 Vacuum Tubes NOS NIB RCA OSCThis 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

100% is 56/56

Tube One measured 60 while Tube Two measured 62 where minimum (65%) is 55 and 100% 85

They have DC and BD date codes

These four Ken-Rad tubes tested as follows on our Paul Hart-calibrated TV7/U:

They measured 23

This General Electric 22JF6 tube tested 75 on our Paul Hart-calibrated TV7/U where minimum is 54 and new is 100

Here's a new old box

280 739 and F1 date codes

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

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

both with current readings of 34 and transconductance of 3520

This lot of three US-made type 42 tubes was tested our Paul Hart-calibrated TV7/U for shorts