Power Pentode
The 3S4 vacuum tube is a miniature type used in the
output stage of lightweight,
compact, portable, battery-operated equipment. It requires
a miniature 7-contact socket. Except for filament
arrangement, it is identical to 1S4.
Electrical Data:
Heater Voltage ........................ 2.8/1.4 DC V
Heater Current .......................... 0.05/0.1 A
Preferred Substitutes ...................... 3Q4 3W4
Substitutes .................................... 3Z4