The EL34 is a much loved audio power valve with an anode dissipation of 25 Watts. In this example we see that other manufacturers produced copies of the Mullard classic. (See EL34 for the original.)

Looking into the anode cavity the three wire grids can be seen, with the control grid of fine pitch close to the central cathode and the final suppressor grid appearing as a lazy spiral of wide spacing.

The wide glass tube envelope is 34 mm in diameter and excluding IO base pins the valve is 95 mm high. Type EL34 was first introduced^¶ in 1952.

 
Pin Connections

IO	1	2	3	4	5	6	7	8
	g3	h	a	g2	g1	nc	h	k

 
Absolute Maximum Operating Conditions^¶

Pentode	Vh	Ah	Va	Vs	Vg	mAs	gm	Vg	Pdiss	Pout	D
	6.3	1.5	800	400	-39,mAa_91	19	11.0	66	25W	100W	5%

Thanks to Frank Philipse for supplying the above PDF datasheet

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