The 17Z3 is an efficiency diode for television line scan and the design dates to the early 1950s. This was a popular design and was made by many companies under various Type designations. Pinnacle have shown this by marking the envelope PY81, U153 as well as 17Z3.
The rectifier is specified as having a peak inverse voltage rating of 4,500 Volts, and a peak current rating of 450 mA.
The anode plates are carbonised on the outside but bright on the working face.
The two anode sheets are stitched together. The overall width is 15 mm.
The thin glass tube envelope is 21 mm in diameter and, excluding the B9A base pins, is 74 mm tall.