The tube called the TWIN TRIODE appeared in October 1938. It had two separate triodes in one envelope. This tube had both plates coming out one side and the grids coming out the other. The elements were arranged vertically. The name TWIN 30 appears later and may be this same tube or the one shown with horizontally arranged elements. The tube had a mu of 37 and a maximum frequency of 300 MHz.
Length = 4.75" Diameter = 1.75"
Max voltage = 1500
Max current = 85 ma per section
Fil voltage = 6
Fil current = 4 amps