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The U30 is a full wave rectifier from the 1930s. It is specified for a 250-0-250 input and can deliver up to 120 mA. It is interesting that the valve has separate cathodes brought to base pins. Technically this gives flexibility in that full wave, parallel half wave and voltage doubler circuits are all possible. No value is given for the heater to cathode voltage and so it may not be assumed that voltage doubling was possible at the full 250 Volt input. With the 300 mA heater requirement and the 120 mA output it is possible that this valve would have found use in the Television receivers of the late 1930s as well as Universal mains radio receivers.

The typical M-OV type stamp is seen on the envelope. Within can be clearly seen the mesh anode with the cathode inside. the getter and pinch are on the left.

The classic envelope is 47 mm in diameter and, excluding the B7 base pins, is 105 mm tall.

References: Data-sheet & ¹⁰⁴³. Type U30 was first introduced in 1934. See also 1934 adverts.

Pin Connections

Absolute Maximum Operating Conditions^¶

Thanks to Frank Philipse for supplying the above PDF datasheet.