Sensibly equivalent¶ to:
The 13DHA exhibit is a double diode triode. The 200 mA heater suggests mains use in AC/DC sets. The double diode triode was extensively used in superhet receivers as signal detector, AGC rectifier and first audio amplifier stage.
In this image from Mike Edwards the internal structure can be seen. The triode is at the top with a mesh anode and the control grid extending above the anode below the top mica. The diode anodes are shielded by the lower box and are formed from vertical rods.
The classic envelope is 43 mm in diameter and, excluding the B7 base pins, is 104 mm tall.
References: Datasheet & 1043. Type 13DHA was first introduced in 1934.
Absolute Maximum Operating Conditions¶
Updated March 17, 2018. shape:classic construction:pinch type:double.diode.triode age:1930.1940 base:b7 heater:200ma pins:7 pin:1.a(d2) pin:2.m pin:3.a(d1) pin:4.h pin:5.h pin:6.k pin:7.a pin:tc.g1