Original Cossor  DDT tube

11A2 A23A AC/HL/DD HD4 MHD4 TDD4
The Double-Diode Triode
The DDT is a double diode triode for detection and first AF amplifier in superhet receivers. It was introduced in 1933 and the data-sheet makes it clear that it was intended for Automatic Volume Control (now called AGC)

 the tube seems to be slightly used, pretty high emission:

tested in conditions: f=4V Ua=200V Ug1=-3V

 Ia = 3mA

where 100% for the new tube is about 3,4mA

the tube has British old 7-Pin (B7, M7A) base

you will get the tube you can see at the pictures

I always send the tubes by priority registered mail with tracking number within hours after receiving payment

                                                                                                                Santic [feat. Vera Hall] – Trouble So Hard