Abstract: A magnetron unit has a magnetic flux path for magnetic flux supplied from a permanent magnet to the interaction space. A magnetic member is disposed outside the anode cylinder for providing a by-path for the magnetic flux supplied from the permanent magnet. This magnetic member is made of a magnetic compensating alloy whose magnetic permeability decreases with an increase in temperature.

Abstract: In a magnetron comprising a cylindrical anode, a cathode positioned coaxially in the anode, an output portion extending from the anode, an annular magnet, a yoke having a larger diameter opening extended through by the output portion, and a gasket a magnetic shim plate is provided between the permanent magnet and the yoke so that the entire surface of the permanent magnet is in magnetic contact with the yoke. A continuous magnetic circuit is thereby formed to prevent the formation of any gaps to avoid fluctuations or reduction in the magnetic flux.

Abstract: An internal magnet type magnetron is provided with a pair of permanent magnets which are disposed facing each other in a cylindrical envelope. In a space between the permanent magnets, a cathode is disposed around which a number of vanes extend radially. An output conductor is connected to one of the vanes and is extended through a space around one of the permanent magnets to an output section attached to the envelope. Most of the output conductor part passing through the space around one of the permanent magnets is enclosed by an outer metal tube. An inner tube having a length as large as 1/4 of harmonic wave .lambda.n is disposed in the outer metal tube. The inner and outer tubes are both electrically connected to the envelope.

Abstract: A magnetron includes a high frequency generating source having an anode and a cathode, two power supply conductors for supplying electric power to the cathode of the high frequency generating source, filter circuits inserted in the power supply conductors for damping and suppressing the high frequency components leaking through the power supply conductors and a shield box covering the two power supply conductors and two filter circuits. Each of the filter circuits includes a capacitor and a choke which is comprised of an coreless type inductor made of coreless coil and a core type inductor made of ferrite-cored coil. The coreless type inductors of two filter circuits connected to the respective different power supply conductors are different each other in inductance.