The PY32 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 100 µF.
Peter Bates, who donated some PY32's, comments that he has tested many PY32's and generally the older style twin cathode PY32's last longer than the later single system valves like this one.
The PY32 was replaced by the PY33 that featured greater maximum current and twice the reservoir capacitance, suggesting a better surge rating and therefore a more emissive cathode.
The 300 mA heater was the standard for TV receivers from the 1960s.
The wide glass tube envelope is 30 mm in diameter and, excluding the IO base pins, is 92 mm tall.
References: Peter Bates, datasheet & 1040. Type PY32 was first introduced in 1955.