Sensibly equivalent¶ to:
210DDT AR10 CV1308 CV2985 DDT2 L21DD TDD2A
The HD24 is a directly heated double diode triode that would have been used in broadcast receivers, as detector, AGC detector and first audio amplifier. The metal paint is flaking off of the glass leaving little residue of the adhesive. Our other HD24 was made for the consumer market and has a plain envelope.
The HD24 has a lower filament consumption than the HD23 which itself was designed to lower the filament consumption and thus replace the HD21 and/or HD22. The HD24 has a lowest anode current rating of the series.
The classic envelope is 40 mm in diameter and, excluding the B5 base pins, is 98 mm tall.
References: Datasheet, 1040 & 1043. Type HD24 was first introduced in 1939.
Absolute Maximum Operating Conditions¶
Updated March 18, 2014.