Vacuum Tube - 5755 / 420A, Dual Triode
New-Old-Stock (NOS) tube.
The 420A electron tube is a double-triode having separate indirectly heated cathodes. The heater is center-tapped to permit operation from a 6.3 or 12.6 volt filament supply. This tube has been designed for use in d-c amplifier circuits where tube requirements include a high order of mechanical and thermionic stability as well as long life expectancy.