The EABC80 is a triple diode triode. This exibit is of Foreign origin, our other example EABC80 is British made.
The triode and two diodes share a common cathode but one diode has a separate cathode.
The EABC80 was specifically designed (1954) for use in the detector stage of early FM and FM/AM radios. The triode section providing the first audio amplification, the single diode and one of the diode pair were used as an FM detector in a ratio detector circuit. The other diode in the pair being used as the AM detector when that part of the circuit was required.
This design was also produced in versions for universal sets (no mains transformer). SeeUABC80 and PABC80.
The three sets of electrodes seen end on. The plate seen ascending on the right is one of a pair that carry the heater voltage to the top of the electrodes. The three sections have their heaters in series and all connected from the top.
The series connected heaters are at the top. The triode is on the left, the twin diodes in the centre and the single diode on the right.
The thin glass tube envelope is 20 mm in diameter and, excluding the B9A base pins, is 58 mm tall.
References: Data-sheet, 3002 & 1040. Type EABC80 was first introduced in 1952.