Abstract: A magnetron including a cathode, an anode axially aligned with the cathode and including a plurality of radial vanes defining resonant cavities, an output coupler connected to a first set of the vanes, a second set of vanes not connected to the output coupler, and extensions formed on only the vanes of the second set, the extensions extending in the axial direction towards the output coupler in a direction parallel to the axis of the anode, the extensions not being connected to the output coupler, whereby a capacitance between the axial extensions and the cathode at least partly compensates for the capacitance between the output coupler and the cathode.

Abstract: A magnetron has a first set of vanes etc which connect by legs to a coaxial output coupler and a second set of vanes etc which (in one embodiment) alternate with the vanes of the first set and are not connected to the output coupler. The vanes of each set are held, for example, by strap rings which may be distributed along the length of the anode, at the same potential as each other, and the polarity of the vanes of one set is opposite to that of the other set. A problem with such a magnetron is that there is capacitive coupling between the cathode and the output coupler, which can lead to the coaxial TEM mode propagating along the cathode. According to the invention, additional capacitive coupling is introduced by means of axial extensions 19a etc on the ends of the set of vanes etc which are not connected to the output coupler, and by choice of dimensions, the cathode is substantially decoupled from the output coupler because of the opposite polarity of the two sets of vanes.

Abstract: A collector for an electron beam tube comprises a plurality of electrode stages. The electrode stages are spaced from one another by a non-conductive spacer. The non-conductive spacer is located between portions of electrodes and extends into the collector on a first side and out of the collector on a second side. The non-conductive spacer has an inner portion extending into the collector and an outer portion extending out of the collector and a waisted portion there between. The spacer is held at the waisted portion.

Abstract: A linear electron beam tube comprises an electron gun having a cathode and a grid, and an anode arranged in a first portion of a drift tube. The drift tube is within a vacuum envelope and has first and second portions separated by a gap at which point an electron beam, density modulated with an input RF signal is inductively coupled to an output cavity. The vacuum envelope is partially defined by a cylindrical ceramic wall and a pair of ferromagnetic pole pieces at its ends that form a DC magnetic circuit. The pole pieces extend radially beyond the vacuum envelope. At least those parts of the surface of the pole pieces that are in the RF path are coated with a layer of relatively low RF loss material such as copper. A balance ring separates the ceramic from the pole pieces.

Abstract: An r.f. radiation absorbing material able to hold off a 30 to 40 kV voltage difference is described as formed by a silicon rubber loaded with ferrite particles. The material is used to reduce self-oscillation in amplifiers.