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This valve was made for domestic radio receivers. It contains a sensitive high slope power pentode to drive a loudspeaker. It was used in place of two valves, the first Audio Frequency (AF) stage and the power output stage.

It also contains two diodes, one for detecting the AF from the Intermediate Frequency (IF) stage, the other to provide an Automatic Gain Control (AGC) voltage for previous stages.

Usually the diodes were in the valve used in the IF stage or sometimes the first AF stage.

It was not a popular valve and had limited production.