Power supply for a microwave magnetron

In combination:

• a transformer, said transformer having a core of ferrite magnetic material with said core having a gap of nonmagnetic material between ferrite portions thereof,
• a primary winding,
• a first high voltage secondary winding,
• a second low voltage secondary winding,
• a third low voltage secondary winding,
• a fourth low voltage secondary winding, with said windings located on said ferrite core;
• said primary winding having a predetermined electrical inductance characteristic and having first and second winding ends and a center tap connected to essentially the middle of said primary to thereby divide said primary into first and second primary winding halves;
• first and second semiconductor switch means, each of said switch means having a control input and a pair of output terminals for providing a low impedance current conducting circuit between the output terminals during the interval in which a suitable control voltage is present at the said control input thereof;
• rectifying means, said rectifying means having an input and output, with the input connected to said second secondary winding, said rectifying means responsive to AC voltage at an input for applying DC voltage to its output;
• means, including resistance means, coupling the output of said rectifying means in circuit with a control input of one of said semiconductor switch means for applying a DC bias voltage thereto;
• means connecting said third secondary winding in circuit between the control input of said first semiconductor switch means and the control input of said second semiconductor switch means for applying any AC voltage appearing thereacross said winding to said control inputs in an opposite phase relationship, whereby a suitable control voltage is applied to the control inputs of said switch means one-at-a-time during each cycle of AC voltage;
• a magnetron for generating microwave frequency energy, said magnetron having a heater-cathode and an anode;
• means coupling said fourth secondary winding in circuit with said heater cathode of said magnetron for applying high frequency low voltage AC from said winding to said heater;
• a rectifier diode having an anode and cathode;
• means connecting said rectifier diode in circuit across said magnetron with the cathode end thereof connected to the magnetron anode for permitting the diode to conduct current when the polarity of voltage thereacross is of one polarity and permitting the magnetron to conduct current when the voltage thereacross is of the opposite polarity;
• first capacitor means;
• means connecting said first high voltage secondary winding, said capacitor means, and said parallel combination of rectifying diode and magnetron in an electrical series circuit;
• means connecting one of said primary winding halves and said output terminals of said first semiconductor switch means in a first current conducting path;
• means connecting the other of said primary winding halves and said output terminals of said second semiconductor switch means in a second current conducting path;
• and
• a source of DC connected to both said current conducting paths, said source including:
• means for supplying an inductively smoothed DC current into said primary winding, whereby a high frequency AC voltage is generated across said primary winding and in each of said secondary windings.