DW30 pair directly heated rectifier, dated 1929 the first ever made of its kind nickel plate

Description

One of the first directly heated rectifier ever made by Mullard named DW30.

We offer two versions: one balloon shape and  one pip top.

Large bulb audio valves the best of their kind.

Early type made in 1929 with flat nickel plates and filament held by two ‘springs’ on top.

The identification of these valves can be read on top of dome working at 7.5 V filament tested 100% emission, that is the balloon one.

The DW30 pip top has lettering on side of glass.

Both rare valves!