The EC50 is a gas filled triode. The trade name and now the generic term is thyratron. In the case of the EC50 the filling is low pressure helium.
The 1930s valves (SeeGT1C) operated at less than 10 kHz whereas this later design is rated up to 150 kHz. Note the carbonised outer electrode and grid heat sinks in this higher speed device.
The electrodes side elevation.
A close look at the connections reveals that the black mesh is connected to the cathode and is connected to the heated central cathode. Heat sinks attach to the copper control grid supports.
The anode is a cylinder inside the outer mesh and connects to the top cap via a glass insulated wire.
The classic envelope is 43 mm in diameter, and excluding the cT8 base pins is 100 mm tall.
References: Data-sheet. Type EC50 was first introduced in 1953. See also1953 adverts.
