The ZA3489 is a full wave rectifier based on the commercial 5Z4G designed to supply equipment of up to 40 Watts total power.
Professional equipment, including radar, etc., sometimes required circuits in which valve cathodes carried large signals and had to 'float' at voltages well below that of the chassis.
The valve meets the CV1863 specification and the ZA indicates that it was made by M-OV at the Gateshead factory, before March 1957.
The CV1863 was also the designation for the 5Z4GY rectifier with the moisture resistant base for airborne and tropical use.
The heater is a single hairpin within the cathode tube.
The IO base has five fins fitted.
Thanks to Mark Mallison for sending the images.
The classic envelope is mm in diameter and, excluding the IO base pins, is mm tall.
