Sensibly equivalent¶ to:
The PX4 is one of the classic audio power triode valves and was first introduced in 1929. 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.
See also PX4.
The electrode system is only about 5 mm from front to back, but is 30 mm wide and 45 mm high.
The classic envelope is 48 mm in diameter, and excluding the B4 base pins is 120 mm tall.
References: Datasheet, 1005, 1040 & 1043. Type PX4 was first introduced in 1929.
Absolute Maximum Operating Conditions¶
Updated April 05, 2015. shape:classic construction:pinch type:triode age:1920.1930 base:b4 heater:4.0v pins:4 pin:1.a pin:2.g1 pin:3.f pin:4.f