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).