The magnetron is also called the microwave generator, and the working frequency is generally around 2450MHZ. It consists of a filament, cathode, anode and microwave energy output.
First, the composition of the magnetron:
(1) Filament: It is spirally formed by twisting tungsten wire or pure tungsten wire, and its function is to heat the cathode. The general working voltage is 3.3V and the current is about 10A.
(2) Cathode: The cathode is made of a material that emits electrons. It is divided into direct heat and interheat. After the cathode is heated, its surface quickly emits enough electrons to maintain the current required for the magnetron to operate properly.
(3) Anode: There are several resonant cavities on the anode, mostly in the form of holes and fans, made of oxygen-free copper to receive electrons emitted by the cathode. They are frequency selective resonant circuits that generate high frequency oscillations. The resonant frequency is primarily determined by the size of the cavity. The upper chamber of the anode block faces the cathode and generally has an even number. For safe use and easy installation, the anode is grounded and the cathode is connected to a high voltage of about 4000V, so that a radial DC electric field is formed between the anode and the cathode.
(4) Microwave energy output device: The microwave energy generated by the magnetron is coupled out and sent to the load for heating the food. (The role of the magnet is to supply a strong magnetic field parallel to the anode axis, usually in a simple structure, made of permanent magnets.)
Second, the working principle of the magnetron:
A constant DC voltage is applied between the anode and the cathode, and the electrons emitted from the cathode are affected by the positive potential of the anode to fly toward the anode, and then the magnet acts. There is a magnetic field in the space perpendicular to the electric field, and thus the electron is in the magnetic field force. And the electric wheel force acts as a wheel swing. Due to the presence of a high-frequency electric field in the anode cavity, an "electron cloud" is formed around the anode; when the rotational speed is synchronized with the high-frequency magnetic field, the electrons deliver all of the energy to the high-frequency magnetic field, thereby maintaining high-frequency oscillation. This high-frequency energy is output through a microwave energy output device that is transmitted by a waveguide to a microwave oven to heat the food.
Third, the magnetic tube is good or bad measurement method:
(1) After shutting down, discharge the high voltage capacitor and unplug the two plugs of the magnetron filament.
(2) Measure two filaments with a multimeter × 1 ω resistance file, which should be less than 1ω.
(3) Measure any filament to the ground (metal casing) with x10k file is infinite. Otherwise it is broken.
BK120
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