RCA 12BH7 12BH7A Vacuum Tube Valve NOS NIB Zenith Octal

RCA 12BH7 12BH7A Vacuum Tube Valve NOS NIB Zenith OctalThis new old stock testing RCA 12BH7A was tested on our Maxi Preamp II for shorts, gas, noise, transconductance and gain. There were no shorts, noise or gas and it tests as follows: Noise: 84. 3 dB 83. 6 dB ( 92 dB is the Maxi Matcher's noise floor) Transconductance: 2219 2211 (M M has no recommended value. New 12BH7s have averaged 2200 to date) Gain (Mu ()): 17. 1 16. 5 (New nominal is with a standard deviation of 16 16) As I write, I am playing it

7 (New is approximately 17)

This Raytheon (JAPAN) 12SN7GTA dual triode was tested on our Paul Hart-calibrated TV7 for shorts

4 milliamps' plate current while Tube Two drew 21

ONE IS MISSING

All measured 2100 micromhos where new/nominal is 2000 and minimum (65%) is 1300

These three GE 6EU8 tubes tested to spec on our Paul Hart-calibrated TV7/U

This lot of seven GE new old stock

This matched pair of Sylvania black plate 12BY7 / 12BY7A tubes was tested on our Paul Hart-calibrated TV7/U for shorts

new in box US-made 22BH3 tubes tested to spec on our Paul Hart-calibrated TV7/U

I am playing them as I write in my Alan Eaton single-ended triode amplifier with Talking Heads' "Fear Of Music" and they sound outstanding

Transconductance measured 1950/1850 where minimum (65%) is 1430

excellent flashing and 58-39 188-5 date/factory codes