Maker's Name: 
Standard Telephones and Cables
Where made: 
10 × 13.2 × 52 cm

This  is a water-cooled valve used at Bald Hills radio transmitting station. It was capable of generating 10 kiloWatts output Class C, or could be used for an AF modulating amplifier.

The filament is pure Tungsten, requiring 21.5 Volts at 41 Amps, to provide a plate current of 0.75 Amp.

The valve was mounted vertically with the copper thimble pointing down and immersed in a water jacket. It required a constant flow of distilled water, tested regularly to ensure it was not contaminated.