Sensibly equivalent¶ to:
11A2 A23A AC/DDT AC/HL4DD AC/HLDD CV3727 DDT4 DDT4 DDT4160 DDT DT41 DT436 H4D MHD4 TBC14
The TDD4 is an indirectly heated double diode triode for mains superhet receivers. It was designed for signal and AGC detection and then as the first post detection amplifier.
We have several versions, this is believed to be of post WWII manufacture but the design dates to 1933. The style of the Mullard logo is the guide.
The classic envelope is 35 mm in diameter and, excluding the B7 base pins, is 106 mm tall.
References: Datasheet & 1043. Type TDD4 was first introduced in 1933.
Absolute Maximum Operating Conditions¶
PDF scanned from an original document held by the museum
Updated December14, 2012. shape:classic construction:pinch type:triode age:1930.1940 base:b7 heater:4.0v 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