The ECF802 was designed as the first stages in television line frequency generation prior to the line output stage. The pentode is described as the oscillator while the triode is for service as a reactance valve. This suggests the triode acting as a frequency controlling stage.
Domestic sets would use the 300 mA series heater chain version the PCF802, whereas this type would be used in professional monitors etc. where an isolation mains transformer would be present.
The triode on the left is set behind the screen and normal to the pentode grid axis.
The triode face view. The mica sheets are doubled to confer stability of the electrodes when operated in aircraft or other places where vibration exists.
The thin glass tube envelope is 20 mm in diameter and, excluding the B9A base pins, is 47 mm tall.
References: Data-sheet, 3002 & 1040. Type ECF802 was first introduced in 1961. See also1961 adverts.
