The Type 56 is an indirectly heated audio triode on an American UX5 base.

The electrodes seen in close-up. The blackened anode obscures the grid, but the spacing of the wire can be seen from the notches in the wire supports as they protrude above the mica. The cathode tube is round and matched the anode, this suggests that the grid will also be formed as a spiral.

Many thanks to Simon Balderson for donating these images and valve details.

The classic envelope is 39 mm in diameter, and excluding the UX4 base pins is 90 mm tall.

 
Pin Connections

UX5	1	2	3	4	5
	h	a	g1	k	h

 
Absolute Maximum Operating Conditions

Triode	Vh	Ah	Va	Vg	mAa	ra	gm
	2.5	1.0	250	-13.5	7.5	9,500	1.45

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This exhibit was last updated on 31 March 2008