DO25 Mullard balloon triode audio output valves same shape full cup getter black plate quartet tested 100%

Description

First introduced in 1930 the Mullard DO25 is a power output triode.

The DO25 Mullard is a directly heated triode audio output valve with a 25 Watt anode dissipation.

The filament consumption was first started at 1.8 but later dropped to 1.1 amps only

Filament Volts 6

Oxide filament

Filament Amps 1.8 to 1.1 then

Anode Volts 400

Anode mA63

Grid -95

mA/V 2.6

This is a tested quartet of Mullard DO25 tested at

Mullard DO25 tested 58mA 100%

Mullard DO25 tested 60mA 100%

Mullard DO25 tested 61mA 100%

Mullard DO25 tested 60mA 100%