The UL41 is an audio output pentode from 1953. The U series were designed to operate with a heater chain across the mains in the days when AC mains had not reached all parts of the country. 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 UL46 is electrically very similar to the UL41 but the base connections differ and it was designed for video output.

The two halves of the anode are held together by being stitched as shown.

The copper control grod supports are fitted with small heatsinks at the top.

The thin glass tube envelope is 20 mm in diameter with the base of the envelope containing the pip being 21.5 mm diameter. Excluding the B8A base pins the valve 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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