Type 836 is an American high voltage half wave rectifier. The maximum peak inverse voltage on the anode is 5,000 Volts and the peak cathode current is 1,000 mA.
In side view the support struts to the top mica can be seen as can the locating pin for the bayonet base.
The anode is made in one piece but is divided in the middle for most of its length.
The working cylindrical space on each side of the anode has a single strand filament in the centre.
The classic envelope is 61 mm in diameter and, excluding the UX4 base pins, is 147 mm tall.
References: Data-sheet & 4061. Type 836 was first introduced in 1938. See also1938 adverts.