The U18/20 is a medium power full wave rectifier. We have two examples in the collection. This version is in a longer and narrower envelope than U18/20 but despite different anode construction and envelope size the electrodes are the same size.

To protect the cathode from damage the rectifier needs to be fed from a supply with an effective series resistance of 180 Ohms. The reservoir capacitor may have a maximum value of 16 μF

The classic envelope is 46 mm in diameter and, excluding the B4 base pins, is 124 mm tall.

 
Pin Connections

B4	1	2	3	4
	a(2)	a(1)	f	f

 
Absolute Maximum Operating Conditions

Rectifier	Vh	Ah	Va	mAa
	4.0	3.0	500	275

Thanks to Frank Philipse for supplying the above datasheet

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This exhibit was last updated on 12 June 2007 {find valves by name}