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 WW2 manufacture but the design dates to the early 1930s. 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.

 
Pin Connections

B7	1	2	3	4	5	6	7	tc
	a(d2)	m	a(d1)	h	h	k	a	g1

 
Absolute Maximum Operating Conditions

Triode	Vh	Ah	Va	Vg	mAa	ra	gm
	4.0	0.65	250	-7	4.0	13,500	2.0

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This exhibit was last updated on 21 July 2005