Where made: 
10 × 10 × 36 cm

This valve was used in Chain Home Low (CHL) Radar in England which provided up to 20 minutes early warning of approaching enemy aircraft. The RAF could thus conserve fuel by not having planes flying around the clock to spot approaching aircraft. The defending aircraft could also be accurately directed to the enemy's position and height, providing the element of surprise. The radar operated in the VHF range. This valve provided a large energy pulse at 23kV to supply the final output stage through a modulation transformer.