RCA 12BH7 12BH7A Vacuum Tube Valve NOS NIB Zenith Octal This lot of seven GE

This lot of seven GE new old stock

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

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

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

RCA 12BH7 12BH7A Vacuum Tube Valve NOS NIB Zenith Octal This lot of seven GEThis 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