Matched Pair RCA 6FQ7 / 6CG7 Vacuum Tubes NOS NIB 35 Thirtyfive new in box Sylvania 5U8

new in box Sylvania 5U8 tubes tested to spec on our Paul Hart-calibrated TV7/U

Transconductance measured an outstanding 92/93 for Tube One and 94/93 for Tube Two where minimum (65%) is 50/50 and 100% is 77/77

The reference to "Uncle Doug" is a hat tip to The Most Sublime Guitar Amplifier Guru who recommended a significant -- but not-too-large -- difference in plate current draw for just that right amount of push-pull distortion

Tube One measured 57/58 while Tube Two measured 58/58

There were no shorts or gas and emissions measured as follows:

Matched Pair RCA 6FQ7 / 6CG7 Vacuum Tubes NOS NIB 35 Thirtyfive new in box Sylvania 5U8This new old stock, new in box matched pair of RCA 6FQ7 6CG7 dual triodes was tested on our TV7 U for shorts, gas and transconductance. There were no shorts or gas and their readings are as follows: Tube One measured 75 75 while Tube Two measured 77 75 where minimum (65%) is 50 50 and 100% is 77 77. These tubes have steel support rods; ladder plates and side D getters. I played them with adapters (not included) in my Radio Craftsmen RC 2 monoblocks