The UY85 half wave rectifier was designed for use across the European mains, as the 100 mA heater suggests. The reservoir capacitor specified is 100 µF and the minimum effective series resistance in the circuit needed to be only 100 Ohms.

The design use was in domestic broadcast receivers for the main HT rail.

The anode is carbonised on the outside and left bright on the inner surface. With the plates opened at the ends into extra fins the inner surface becomes revealed.

The thin glass tube envelope is 20 mm in diameter and, excluding the B9A base pins, is 58 mm tall.

References: Datasheet & ¹⁰⁴⁰. Type UY85 was first introduced^¶ in 1954.

 
Pin Connections

B9A	1	2	3	4	5	6	7	8	9
	ic	ic	k	h	h	ic	ic	ic	a

 
Absolute Maximum Operating Conditions^¶

Rectifier	Vh	Ah	Va	mAa
	38	0.1	250	110

Thanks to Frank Philipse for supplying the above PDF datasheet

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