The DH76 double diode triode was designed for broadcast receiver use.

The diodes would be for signal and AGC rectification and the triode would act as AGC amplifier or first audio amplifier.

The Marconi brand of the M-OV company is fixed to the envelope.

The triode is at the top and has a carbonised anode. The signal diodes are bright plates below the triode and have the common cathode passing through them.

The triode close-up. The grid supports extend above the top mica and the top cap wire is welded to one. The two halves of the anode are self fixed with notches and lugs.

The wide glass tube envelope is 28 mm in diameter and, excluding the IO base pins, is 87 mm tall.

References: Datasheet, ¹⁰⁴⁰ & ¹⁰⁴³. Type DH76 was first introduced^¶ in 1947.

 
Pin Connections

IO	1	2	3	4	5	6	7	8	tc
	m	h	a	a(d2)	a(d1)	nc	h	k	g1

 
Absolute Maximum Operating Conditions^¶

Triode	Vh	Ah	Va	Vg	mAa	ra	gm
	13.0	0.16	175	-1.3	0.4	58k	1.2

Thanks to Frank Philipse for supplying the above PDF datasheet