GB582616A - Improvements in or relating to electron discharge devices employing hollow resonators - Google Patents

Abstract

582,616. Velocitymodulated tubes. BROADWAY, L. F., and BULL, C. S. May 21, 1941, No. 6528. [Class 39 (i)] In a circuit arrangement for mixing highfrequency oscillations in a radio receiver, an electron beam, after having been subjected to velocity modulation or passing through a hollow resonator, impinges on a target electrode which emits secondary electrons in greater number than the incident primary electrons ; the secondaries pass to a collector or to a further electron multiplier. The velocity modulation may be imparted by electrodes with which the beam is indirectly coupled or the beam may pass through grids of resonators 5, 7 which act as a mixer, local oscillations being applied to one loop 6 or 8 and a signal to the other. The beam may be circular in section and after passing the suppressor grid 9 impacts the secondary emitter electrode 10 ; the collector electrode 11 is tubular. The resonators and beam may be of the shapes described in Specifications 572,540 and 577,037. In a modification, the resonators 5, 7, Fig. 2, are built together, the discharge envelope 7d passing through them ; the suppressor grid 9 forms one of the grids of the resonator 7, the end wall of which is capacity coupled to the remainder through the plates 7a, 7b and dielectric 7c. In another arrangement, both local and signal oscillations are applied to a single resonator whose walls 12, 13 are capacity coupled ; the modulated beam falls on the target 14, which is the first of a number of multiplier electrodes which may work as described in Specification 534,208. Low velocity electrons reflected by the grid 9 may cause one of the resonators to act as a generator of self-maintained oscillations.