The PY33 is an HT rectifier for television receivers. It operates directly from the mains input and with a series resistance of 25 Ohms it will feed a reservoir capacitor of 200 µF. The 300 mA heater was the standard for TV receivers from the 1960s.
The anode is formed from a plate that has been machine stamped to shape, folded and then stitched together with lugs pressed out of the anode material.
The pressed glass foot can be seen. This hard glass disc carries the lead-out wires and support structures. The mica supports can also be seen.
The wide glass tube envelope is 32 mm in diameter, and excluding the IO base pins, is 95 mm tall.
References: Data-sheet & 1040. Type PY33 was first introduced in 1961.