The 1821 is a Philips full wave rectifier on a B4 base with a brown composition base.

The dome of the envelope contains the etched lettering. It is unusual to see a Philips valve showing as Made in England, possibly this was made for export.

See also UU5 for approximate operating parameters.

The balloon envelope is 52 mm in diameter and, excluding the B4 base pins, is 106 mm tall.

This exhibit was last updated on 03 July 2006