U31 @ The Valve Museum

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U31

Sensibly equivalent^¶ to:

25Z4 CV3753

See also:

Osram KT2, KT63, KT61, KT66, PX4, U50, KT76, KT33C, KT71, U76 & U31 Advert

Extras ▼

Marconi The Hampshire Collection Other U31 exhibits

The U31 half wave rectifier was designed for series heater use.

The maximum reservoir capacitor specified is 32 µF and the minimum effective series resistance has to be 100 Ohms.

See also U31.

The remains of the Marconi brand label.

The coiled insulated heater passes through the rectangular cathode four times.

The classic envelope is 45 mm in diameter, and excluding the IO base pins, is 103 mm tall.

References: Data-sheet, ¹⁰⁴⁰ & ¹⁰⁴³. Type U31 was first introduced in 1937. See also 1937 adverts.

Pin Connections

IO	1	2	3	4	5	6	7	8
	ic	h	nc	nc	a	nc	h	k

Absolute Maximum Operating Conditions^¶

Rectifier	Vh	Ah	Va	mAs
	26	0.3	250	120

Thanks to Frank Philipse for supplying the above PDF datasheet.

Updated January 06, 2022.

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