Sharp-Cutoff Pentode
The 57 Vacuum tube is a glass type used as biased detctor in ac-operated
receivers.
The 57 Vacuum tube is also a triple-grid tube recommended especially for service as a biased
detector in a-c receivers designed for its characteristics. In s such service, this tube is
capable of delivering a large audio-frequency output voltage with relatively small input
voltage. Other applications of the 57 include its use as a low signal-input, screen grid
amplifier tube and as an automatic volume control tube. The 57 is characterized by the small
overall size, the dome-top bulb, the internal shield in the dome, the rigidity of electrode
assembly, and the fifth electrode or suppressor with its own base pin terminal. Equally
significant among its electrical features are its relatively low heater power consumption, its
sharp plate current cut-off with respect to grid voltage, and its adaptability of electrode
combinations to unusual circuit applications.
Electrical Data:
Heater Voltage ................................ 2.5 V
Heater Current ................................ 1.0 A
Preferred Substitutes .................. 257, UZ-57, A257, VT-57, W2161, PH57, PH257,
ER57, VT155_GPO, CV1704, T-57, NU-57.
Substitutes .................... G-57-S, M57.