Abstract: A high-frequency electron tube power oscillator includes a multi-grid electron tube (1) in which the output power is adjusted by means of an adjustable impedance element (5) connected in series with the cathode line of the tetrode (1). In order to reduce the dissipated power in the adjustable impedance element (5), the voltage across the impedance element is connected to the screen grid of the tetrode (1) through an amplifier (6) constituted by a triode (9) and a current source (10).

Abstract: In order to operate high-frequency heating equipment such as, for example, plasma torches, it is desirable to provide a power generator which will generate a high-frequency high voltage providing a large amount of power. If an oscillator circuit includes an electron tube (1), a control circuit (7) and a frequency-determining circuit that is formed by a coaxial waveguide (11) which is biased in the neighborhood of its short-circuited end a high-frequency high voltage will be obtained at the open end of the waveguide. The power supplied by the electron tube is stepped up to the permissible maximum value for given maximum supply voltage by having the electron tube generate the corresponding current, which is determined by the choice of the point (14) at which the coaxial waveguide (11) is biased.

Abstract: A high-frequency power oscillator includes a tetrode electron tube (5), a current source (3) and a voltage-limiting circuit (4). The current source (3) is connected to the screen grid of the tetrode (5). This limits the screen grid current when the voltage on the anode of the tetrode (5) is momentarily lower than the screen grid voltage. Between the screen grid and the cathode of the tetrode the voltage-limiting circuit (4) is inserted. This circuit starts to conduct above a predetermined threshold value. This forms a limit to the screen grid voltage so that is is possible to operate the tetrode (5) in a pulsating manner. The voltage-limiting circuit may comprise a triode (4) with a voltage source (2) providing a constant voltage between the grid and the cathode of the triode (4).

Abstract: In a high-frequency generator (1) comprising a multigrid electron tube (2), the control grid (3) and the screen grid (4) are substantially d.c. coupled. The tube then oscillates via the internal parasitic capacitance between the screen grid (4) and anode (5) without requiring an external feedback circuit. A reduction of the heat dissipation and a compact electron tube are the result with high oscillation frequencies likewise being attainable. A high-frequency decoupling of the control grid (3), with an intermittent operation of the generator (1), results in a very limited heat dissipation, causing the generator (1) to be very compact.

Abstract: A high-frequency generator 1 includes a multigrid electron tube (2). A current source circuit (10) is connected to the control grid (3) or the screen grid (4) of the electron tube (2) and is arranged as an optionally adjustable current source which is also coupled to the main current path of the electron tube. This circuit defines the grid dissipation and also extends the useful life of the electron tube. If the current source circuit (10) is connected to the screen grid (4), the electron tube is further safeguarded in a simple manner against an inadmissibly high screen grid current accompanying an occasional anode voltage drop.

Abstract: A high-frequency heating generator comprising a multi-grid electron tube 15 for use in industrial systems in the range of several kilowatts to a number of megawatts. In order to obtain an economic high-frequency generator, the electron tube 15 comprises at least two grids 152, 153; of which a first grid 153 is connected to a positive feedback circuit (15') of the oscillator circuit. A source of bias voltage may be supplied to the second grid 152. A low voltage control circuit (16) is connected to either the first (153) or second (152) grid, and the anode 151 is connected to a non-controlled d.c. power source (13, 14).

Abstract: A high-frequency heating generator, comprising an electron tube (B) for industrial systems ranging from several kilowatts to a number of megawatts. In similar systems employing an electron tube oscillator a substantial amount of power is dissipated in at least one control element (T) connected in the electron tube cathode circuit at power leads below the maximum power level of the apparatus. To obviate this drawback, an impedance circuit (Z.sub.K) is connected in parallel with the control element (T), which circuit dissipates part of the power to be dissipated in the cathode circuit.