The key components of the microwave oven magnetron is mainly composed of two parts, the die and the magnet , as shown in Figure 1. The die is constituted by a cathode , a filament , an anode, an antenna ( waveguide ) and the like. Its working principle is : After the power is turned on , 3.3V high voltage generated across the coil filament transformer secondary AC power to the magnetron filament . Meanwhile, about 2000V AC high voltage capacitor by limiting high voltage windings of the diode rectifier get about 2000V DC high voltage applied to the magnetron anode , forming accelerating electric field ( anode grounded , in fact, the cathode is negative 2000V, see Figure 2 ) , a cathode ( of direct thermal and thermal -two rooms , Figure 2 is a direct thermal ) emitted by accelerating electrons to the anode . Also in the vertical direction by the strong magnetic field of the permanent magnet is formed on the anode during the accelerated electrons to the movement, so that electrons are accelerated toward the anode while rotating motion ( like a bullet in the barrel of the movement of the same) , the rotational speed also constantly changing fast. Anode made ​​of the gear-shaped , forming an even number of cavities , called the resonant cavity . Each cavity is a microwave resonator cavity resonance frequency depends on the size . Electrons in the cavity through the fan-shaped oscillation will occur. And the frequency is rising . When the frequency of 2400MHz after they formed the microwave emission from the waveguide mouth, and then transferred to the furnace for heating food .NDPservice manual download site

Mainly to measure the quality of the magnetron filament ( cathode for direct thermal is , the vast majority of direct thermal ) . Including inductance coil with a magnetic core for open circuit , which is between the magnetron filament leads should be through the end (but the shell resistance should be infinite ) , the normal value should be less than 1Ω. It also determines whether the signs of aging , this value is smaller the better , greater than 1Ω description has been aging. For magnetron , there is no uniform nominal model , such as Galanz WD700 same model used in microwave oven and some Toshiba inlet tube , model 2M253K. And some with homemade tube , model , compared M24FB-210A. Best attention to the power pin of the original pipe and installation consistent with the substitution. Power is too small , less than the original heating effect ( although there is some room for adjustment magnetron power ) ; too large , it may damage the high voltage converter or high-voltage rectifier diodes. In addition, the high-voltage fuse characteristics. Mainly shape longer (4cm), with the delay characteristics of the insulation installed in a special box of insurance , general insurance tube can not be replaced . Delay fuses instead of someone with a 3.15A TV , not only fusing current is too large, would not achieve the role of insurance , and its shorter length does not match the high pressure requirements.

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