6S4A RCA branded Sylvania black plate NOS 1960 era (20.6ma)

6S4A RCA branded Sylvania black plate NOS 1960 era

20.6ma

Gm=4300

Tested on Amplitrex

Vplate=250V

Vgrid=-8V

Good Ma range 20-25ma

Good Gm range 4000-4500

(the 6S4A features high plate current at relatively low plate voltages and is capable
of withstanding high pulse voltages)(Vfil=6.3V @ 600ma)
MAX Ratings: Vplate=550V, Iplate=30ma, Pout=8.5 watts
Typical Operation: Vplate=250V, Vgrid=-8V, Iplate=24ma, Mu=16.5, Gm=4500, Rplate=3700 ohms)

– Woo Audio GES Electrostatic headphone amp