Sensibly equivalent¶ to:
The 5W4 is a directly heated full wave rectifier with an oxide coated filament. The reservoir capacitor is given as 4 μF.
This example from Ken-Rad is also marked as a VT-97 indicating that it was a Type supplied to the American government.
The Ken-Rad name on the steel case.
Thanks to Mark Mallison for sending the images.
The thin metal tube envelope is 25 mm in diameter, and excluding the IO base pins is 70 mm tall.
Reference: Datasheet. Type 5W4 was first introduced in 1936.
Absolute Maximum Operating Conditions¶
Updated November 02, 2018. shape:thin.metal.tube construction:glass.disc type:rectifier.fw age:1930.1940 base:io heater:5.0v pins:8 pin:1.s pin:2.f pin:3.- pin:4.a(1) pin:5.- pin:6.a(2) pin:7.- pin:8.f