The 50T was the second Eimac tube and was introduced in advertisements in December 1934. It was so successful and so conservatively rated, that it was replaced by the 100T. The 50T was first rated at 75 watts and had an mu of 12. The 50T was usable up to 250 MHz. The first example appears to be the oldest with no bottom brim on the plate cap, no caps on the grid support legs, a filament support wire and the ribbon grid wire is wrapped around one of the grid legs. The second example has a wide brim on the plate cap, the filament support wire and the grid ribbon is welded to one of the caps that have been added to the grid support glass. The third example has a smaller bottom brim and has lost the filament support wire. Some tubes had simple in-line filament presses as in the fourth example, but most have the typical three support legs. The last example appears to be an experimental having characteristics of the 50T and the 35T. It has the filament support wire like the early 50Ts but does have the caps on the grid support arms.
Length = 7.50" Diameter = 2.87"
Max voltage = 3000
Max current = 125 ma
Fil voltage = 5
Fil current = 6 amps