The 40KG6A/PL519 is a line output valve, or sweep tube as they were known in America. This example is of late manufacture and probably the last to be produced before transistors took over the role. They would be found in large screen colour televisions with an EHT of around 25 kV and thus requiring considerable line drive power. For smaller sets the PL509 would be used as the PL519 was simply an upgraded PL509 with greater anode dissipation.
The parameters given are taken from the data-sheet and refer to pulse operation as line output service uses the valve as a switch delivering current pulses to the output transformer.
Through the holes in the end wall of the anode the inner grids can be seen.The design features aligned wire grids to reduce screen grid current.
The extra anode dissipation over the PL509 is achieved by lengthening the side flanges and turning them through a right angle so that they fit in the envelope.
The top mica showing the rectangular cathode and the two grid supports. The flat tabs are the tops of the beam plates used to repel secondary electrons.
The wide glass tube envelope is 38 mm in diameter and, excluding the B9D base pins, is 114 mm tall.
Reference: Data-sheet. Type 40KG6A was first introduced in 1970. See also1970 adverts.
