High frequency electrical power source with pulsating control

Claim 1

IN A RADIO FREQUENCY HEATING DEVICE INCLUDING A HEATING LOAD AND A RADIO FREQUENCY OSCILLATOR CIRCUIT FOR POWERING SAID LOAD, SAID OSCILLATOR CIRCUIT HAVING A CONTROLLABLE GRID CIRCUIT, THE IMPROVEMENT COMPRISING: A CIRCUIT FOR CREATING A SUCCESSION OF HIGH AND LOW IMPEDANCE LEVELS FORMING A PULSE-LIKE PATTERN WHEN PLOTTED ON A TIME AXIS WITH THE PULSES BEING GENERALLY EQUALLY SPACED; SAID HIGH IMPEDANCE LEVEL BEING SUFFICIENT TO BLOCK OSCILLATION OF SAID OSCILLATOR CIRCUIT AND SAID LOW IMPEDANCE LEVEL BEING INSUFFICIENT TO BLOCK OSCILLATION OF SAID OSCILLATOR CIRCUIT; MEANS FOR IMPOSING SAID IMPEDANCE LEVELS IN THE GRID CIRCUIT OF SAID OSCILLATOR CIRCUIT TO START, SUSTAIN AND AND STOP OSCILLATIONS OF SAID OSCILLATOR CIRCUIT; AND, MEANS FOR CHANGING THE RELATIVE LENGTHS OF SAID HIGH AND LOW IMPEDANCE LEVELS TO VARY THE DUTY CYCLE OF SAID OSCILLATOR CIRCUIT, SAID CREATING CIRCUIT COMPRISING A DUAL TUBE MULTIVIBRATOR CIRCUIT WITH AT LEAST TWO TUBES AND THE PLATE TO CATHODE OF THE FIRST TUBE BEING CONNECTED ACROSS THE GRID CIRCUIT OF THE SECOND TUBE BY A FEED BACK LINE AND AN INTEGRAL WAVE SHAPING CIRCUIT IN SAID FEED BACK LINE TO SHAPE THE OUTPUT PULSES OF SAID SECOND TUBE TO PRODUCE SAID IMPEDANCE LEVELS, GENERALLY VERTICAL TRANSFER CONTOURS BETWEEN SAID LEVELS, SAID TRANSFER CONTOURS HAVING A SLOPE OF 35*-45* DURING THE FIRST ONE-FOURTH OF THE CHANGE IN IMPEDANCE BETWEEN SAID LEVELS.