Philips Q
DC Space Charge Tetrode
1922 (Neth)

The Philips Q tube was the first Philips four element tube and could be used as a detector or amplifier at very low plate voltages. A Q data sheet cautions the user not to apply more than 12 volts to the anode. This tube was made only briefly under the Q designation. Early in 1923 the tube was renumbered to DVI.