The HABC80 is a triple diode triode. The triode and two diodes share a common cathode but one diode has a separate cathode.
Electrically the HABC80 is identical to the EABC80 except for the heater rating. The H prefix denotes a 150mA heater designed for heater chain use. This implies good heater cathode insulation. The xABC80 series was specifically designed 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.
The xABC80 family includes UABC80 100 mA heater, PABC80 300 mA heater as well as the EABC80 with a 6.3 Volt heater.
The valve is a triple tower design. The single diode is on the left, the double diode is in the centre and the triode is on the right. Above the top mica are the tapes that provide the series connections to the three spiral wound heaters.
The triode is at the bottom. The heater interconnections are on the right.
The thin glass tube envelope is 21 mm in diameter and, excluding the B9A base pins, is 61 mm tall.
References: Datasheet, 1040 & 3002. Type HABC80 was first introduced in 1953.