The 6DQ6A is a television line output valve designed for sets with a parallel heater supply. The 12DQ6A and 17DQ6A differ only in heater rating and both are designed for series heater chains and have controlled warm-up characteristics.
The rating given below are for typical applications. In line output service peak anode voltages can rise to 6,000 Volts but an absolute value of DC would be 700 Volts. The anode is rated at 15 Watts dissipation.
The wide flange sits in the centre of the anode where maximum heat is generated and where the additional radiating area limits the rise in temperature. Through the holes in the ends of the anode two inner grids can be seen. The absence of a third wire grid suggests a beam tetrode construction with the beam plates out of sight.
The anode showing the central flange.
The wide glass tube envelope is 38 mm in diameter, and excluding the IO base pins is 90 mm tall.
Reference: Data-sheet. Type 6DQ6A was first introduced in 1956.