The UL41 is an audio output pentode from 1953. The U series, 100 mA heater, were designed to operate with a heater chain across the mains. These universal sets contained no mains transformers and the valves were designed for low anode voltage and higher anode current to provide adequate output. The UL41 could produce 4.2 Watts at 10% distortion.

The cathode resistor suggested for correctly biasing the UL41 was 160 Ohms.

The anode encloses the grid/cathode assembly.

The control grid is fitted with small cooling flanges.

The thin glass tube envelope is 20 mm in diameter, and excluding the B8A base pins is 68 mm tall.

References: Datasheet, ³⁰⁰² & ¹⁰⁴⁰. Type UL41 was first introduced^¶ in 1947.

 
Pin Connections

B8A	1	2	3	4	5	6	7	8
	h	a	ic	ic	g2	g1	k,g3	h

 
Absolute Maximum Operating Conditions^¶

Pentode	Vh	Ah	Va	Vs	Vg	mAa	mAs	ra	gm
	45.0	0.1	170	170	-10.4	53	10	20,000	9.5

Thanks to Frank Philipse for supplying the above PDF datasheet

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