GB493140A - Improvements in or relating to electron discharge devices - Google Patents

Abstract

493,140. Electron - oscillators and circuits therefor. FARNSWORTH TELEVISION, Inc. March 2, 1937, No. 6184. Convention date, March 9, 1936. [Classes 39 (i) and 40 (v)] Oscillations are generated by projecting a stream of electrons from an external electron gun into the space between two opposed electrodes and applying an accelerating positive potential to an anode disposed between the electrodes so as to cause the electrons to oscillate between them without striking so as to give up energy to the electrodes electrostatically before being finally collected by the anode ; the energy so absorbed controls the number of electrons entering the space in such a way as to maintain oscillation. In the form shown, the heated filament 9 emits electrons which pass through a grid 10 and an aperture 6 in an electrode 5 towards a similar electrode 2, the electrodes 2, 5 being connected to a tuned circuit 14 and a transmission line or the like 16. The anode 11 is connected to a source 17 and an axial magnetic or electric field is provided for focusing the electron stream. The grid 10 may be provided with a modulating potential to modulate the output of the device or the device may serve as a Class C amplifier or a separately excited oscillator when a grid exciting voltage is applied through line 23 from a master oscillator, for example. The frequency of the input voltage must then be the same as that of the tuned circuit 14. The device may be provided with a second heated filament, symmetrically arranged behind the electrode 2, when the device is connected for push-pull amplification. Preferably, the field distribution increases parabolically as the electrode 2 or 5 is approached from the anode 11. Specification 488,661 is referred to.