The Pen1340 from Mazda is an audio output pentode designed to be used with a series heater chain in domestic AC/DC receivers.
The side view.
The dome carries the identification etched into the glass.
Here the heat sink fitted to the control grid supports can be seen as can the wire of the suppressor grid.
Looking up from the base, all three wire grids can be seen as well as the flat oxide coated cathode. The heater looks to be s single loop within the cathode.
The classic envelope is 39 mm in diameter and, excluding the B7 base pins, is 100 mm tall.
Reference: Data. Type Pen1340 was first introduced in 1935. See also1935 adverts.
