The EABC80 is a triple diode triode. The triode and two diodes share a common cathode but one diode has a separate cathode.
This exibit is of British manufacture, our other example EABC80 is labelled Foreign.
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). See UABC80 and PABC80.
The thin glass tube envelope is 20 mm in diameter and, excluding the B9A base pins, is 56 mm tall.
Type EABC80 was first introduced in 1952.