The PX4 is one of the classic audio power triode valves and this one is branded Marconi. The design belongs to MOV and so Marconi and Osram are used to brand the valves.

This exhibit lacks the treated anode of later versions and features a bright Nickel anode.

The filament is a single wire formed vertically within the anode cavity into four inverted V's. The grid is a single wire formed between two vertical notched rods 1.5 mm in diameter. The grid zig-zags around the filament.

The electrode system is only about 5 mm from front to back, but is 35 mm wide (including support rods) and 45 mm high. The classic envelope has a maximum diameter of 58 mm and excluding the B4 base pins, is 120 mm long. See also PX4 and PX4

 
Pin Connections

B4	1	2	3	4
	a	g	f	f

 
Absolute Maximum Operating Conditions

Triode	Vh	Ah	Va	Vg	mAa	ra	gm	rk	rl	Pout	D
	4.0	1.0	300	-50.0	50.0	830	6.0	1000	3500	4.5	4.0

Thanks to Frank Philipse for supplying the above datasheet

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This exhibit was last updated on 03 June 2007 {find valves by name}