Negatron

This tube was designed by John Scott Taggart and made by Mullard in 1923. It was made for the Radio Communications Company for use in a special oscillator circuit devised to avoid using Marconi held patents. The tube has two plates and a single grid. The tube name is derived from the negative resistance obtained. A standard Mullard box of the period is shown on page 219 of "70 Years of radio Tubes and Valves" by John W Stokes but is poor quality. The tube picture is little better. Tyne in his "Saga of the vacuum Tube" (page 395) states that the tube was riginally developed in 1919 but was not announced until the patent had been granted.