"Radar" cooking in the early days-it was thought the "microwave" cooker was sort of "invented" accidently-A radar tech was working on a shipboard radar while the antenna was "Rotatin & Radiatin'"And he found a chocolate candy bar in his pocket was melted.Then there was the idea of putting a hot dog on a long stick and holding it in front of and past the focal point of a stationary-but radiating radar antenna-sure 'nough the dog was cooked.Keep in mind radars on ships and stationary ones have more power than a household microwave.For Radars-we are talking about kilowatts of average power and megawatts of "peak" power.For the magnetron to oscillate-like in your microwave-it is not fed with a steady DC HV power.It is fed with PULSED DC.The voltage doubler rectifier circuit in the base of the oven magnetron does just that.the secondary voltage on the ovens power transmformer is about 1200-1800V-the voltage doubler pulsates the voltage to about twice that of the transformer.There is another transformer or another secondary winding that provides the filament power for the magnetron.In a radar transmitter-there is a HV DC supply voltage to the magnetron-like the oven-the base of the tube is "hot" with HV DC.This way the anode(grounded)to the waveguide and chassis.The cathode is fed with negative HV-positive pole of the HV supply grounded.Another supply in the transmitter---The pulse modulator-feeds a pulsed waveform to the cathode of the tube-Giving it the pulsed output.the pulse modulator circuit runs from another HV supply and usually uses a large power tube to amplify a pulse from a smaller pulse generator circuit.The pulse is coupled to the cathode base of the magnetron by a pulse transformer and capacitor network.Often these devices are run in a large tank of transformer oil for insulation and cooling-tube,too.Knew some folks that worked on shipboard and large stationary radars-have some books on them,too.Needless to say these guys that worked on these devices were very careful since they could have supply voltages up to 100,000V!So you grounded ANYTHING in those beasts before handling it.Yes,when I had a magnetron from a scrapped microwave oven-pulsed it with like a 100VDC supply while the filament was lit with a LV transformer-sure enough-a neon bulb placed by the magnetron tubes output probe flashed!