GB1487583A - Magnetron device - Google Patents

Abstract

1487583 Magnetrons TOKYO SHIBAURA ELECTRIC CO Ltd 23 Oct 1974 [12 Nov 1973] 45878/74 Heading H1D High frequency radiation from the cathode leads of a magnetron, e.g. for an oven, is suppressed by including in each cathode lead a first choke element, including a ferrite core of relatively high resistivity, in series with a second choke element including a second ferrite core of relatively low resistivity. Preferably, the first element is connected nearest the cathode. As shown, the cathode heater leads 16a, 16b are provided within the shield box 22, with coils 18a, 19a and 18b, 19b, wound on ferrite cores 20a, 21a of 10 k ohm cm. resistivity, and 20b, 21b of 30 ohm cm. resistivity, respectively. In further embodiments, shield cylinders (26a, 26b, Figs. 3 and 4, not shown) with inner insulating tubes (27a, 27b) are provided around coils 19a and 19b; additional shielding may be provided between coils 18a, 18b and 19a, 19b (Figs. 5 and 6, not shown); a plurality of second choke elements may be provided in series in each lead (Figs. 7A and 7B, not shown), to increase the bandwidth of the noise suppression; the two first choke elements and the two second choke elements may be provided by passing the two cathode leads through a corresponding pair of parallel holes in a single first and a single second ferrite bead (Figs. 8 and 9, not shown); and a repetitive sequence of such first and second beads may be employed (Fig. 10, not shown). The magnetron 11 is provided with a magnet 13 and cooling fins 14.