The 19Y3 is an HT rectifier for use in domestic television receivers.
The minimum effective series resistance that must be in circuit to protect the cathode from surges is 100 Ohms. The maximum reservoir capacitor is 60 μF. The Mullard PY82 has a much lower series resistance figure and thus will deliver greater peak pulse currents to the reservoir capacitor.
This exhibit is an import and branded Cossor.
The anode has four flanges set at right angles around the central cathode.
The two halves of the anode are stitched together with the supports running in grooves.
The thin glass tube envelope is 20 mm in diameter, and excluding the B9A base pins is 70 mm tall.
References: Data-sheet, 3002 & 1040. Type 19Y3 was first introduced in 1952. See also1952 adverts.