Medium-Mu Triode
The RCA Cunningham (Radiotron) 56 Vacuum Tube is a glass
type with an Etched plastic base. It was developed in 1930
and was used as a detector, amplifier or oscillator in
ac-operated receivers. It requires a five-contact socket.
This type is identical electrically to the 76 vacuum Tube.
Electrical Data: ( RCA R-10 - 1930)
Heater Voltage ................................ 2.5 V
Heater Current ................................ 1.0 A
Substitutes .................... 27