The PL504 is a purpose designed television pentode line output valve. It was introduced as a replacement for the PL500.
The peak anode voltage is quoted as 7,000 Volts and shows why the line output stage of a television receiver was the last consumer electronics product to remain a valve. The CRT excepted of course.
De Banks was a reseller not a manufacturer. There is some suggestion that De Banks was part of the same organisation as Pinnacle.
The end of the anode with beam plate within.
The edge of the anode plate. The control grid has heat radiating fins on the tops of the supports.
The wide glass tube envelope is 28 mm in diameter, and excluding the B9D base pins, is 76 mm tall.
References: Data-sheet & 1040. Type PL504 was first introduced in 1961. See also1961 adverts.
