The CV589 is also contains the etched designation 6Q7GT in an octagonal border and the 6Q7GT was the prototype for the CV589. It is a double diode triode and was designed for receiver use.
The diodes would be for signal and AGC rectification and the triode would act as AGC amplifier or first audio amplifier.
The rods entering the lower screening box are the diode anodes. The box connects to the cathode.
The /FB on the base cap identifies the maker as STC Footscray.
Side view.
Here the connection between the lower screen and the cathode is clearer. The lower border of the octagon can be seen to the right of the cathode below the centre mica.
The wide glass tube envelope is 28 mm in diameter and, excluding the IO base pins, is 74 mm tall.
