First, you don't need a magnetron from a microwave oven, it is much to big, stay away from those! i am not liable for your stupidity, its not needed.
however, a small small magnetron needs to be made, in the old days magnetrons was made from vacuum tubes, we will learn and make a smaller one.
a copy and past.
The heart of a microwave oven is the magnetron. A magnetron converts electrical energy to microwave radiation. To do this, it uses low-voltage alternating current and high-voltage direct current. A transformer changes the incoming voltage to the required levels and a capacitor, in combination with a diode, filters out the high voltage and converts it to direct current.
Inside the manetron, electrons are emitted from a central terminal called a cathode. A positively charged anode surrounding the cathode attracts the electrons. Instead of traveling in a straight line, permanent magnets force the electrons to take a circular path. As they pass by resonating cavities, they generate a continuous pulsating magnetic field, or electromagnetic radiation.
