The XGQ2-6400 (MT105) is a tetrode mercury vapour Thyratron that was for maintenance only in 1959. The design applications were industrial eg Motor speed control.
The anode connection is sheathed in glass. The second grid, black cylinder, is secured to a collar on the pinch stem. The first grid connects to the side cap and passes through a ceramic plate to the inside of the second grid.
The first grid terminal.
The collar around the pinch stem is held rigid by the tightening of a bolt through the collar.
The first grid connecting wire is multi stranded. The lower grey cylinder houses the heater/cathode.
The anode connector and the insulated connection passes to the inside of the second grid.
The B4D base and locating pip for the bayonet valve holder.
More detail of the connections.
The classic envelope is 85 mm in diameter and, excluding the B4D base pins, is 258 mm tall.
Reference: Datasheet. Type XGQ2-6400 was first introduced in 1952.