In high-frequency heating equipment, the oscillating electron tube is a precious device, which must be paid attention to in use and maintenance. The following issues will be introduced.
Issues of attention
① Filament voltage should be kept in the range of 10-2~-3%: for pure tungsten cathode tubes, too high filament voltage will seriously shorten the life of the tube; too low will affect the output power. For tubes with thoriated tungsten cathodes, too high or too low filament voltage will affect the life of the tube.
②For the electronic tube whose anode is water-cooled, you must always pay attention to the flow of cooling water, but you cannot rely solely on the indication of the pressure gauge on the water tube. It has been greatly reduced, which will cause the tube to be damaged due to insufficient cooling.
③ To master the purity of cooling water. There are many impurities in the water, and the scale deposits quickly. Limescale in the water pipes can prevent the water from flowing smoothly. The long scale on the anode will affect the heat dissipation, and the scale must be removed regularly. The method of removal is: use 90% water and 10% hydrochloric acid to make a dilute hydrochloric acid solution. Use it to clean the anode to remove scale, and then rinse the residual acid on the anode with warm water. ’
④ When the tube is working, the temperature on the glass bulb is high. The filament and grid are water-cooled tubes to prevent water droplets from spraying on the glass bulb and causing explosions. Therefore, it is necessary to regularly check whether the rubber water pipes are aging and whether the pipe joints are tightened. A baffle can be installed between the water pipe and the glass bulb to prevent accidents.
⑤ The roundness of the inner wall of the water jacket of the electronic tube shall not exceed ± o. 25. The gap between the water jacket and the anode is generally within the range of 3±0.5mm. There are four protruding positioning pins on the upper and lower sides of the inner wall of the water jacket to keep the anode of the electron tube in the center of the water jacket. If the height of the positioning pins is not enough, or the four sides are uneven (the protrusions of the old water jacket will be worn out), the anode will be misaligned in the water jacket. It will cause the anode to overheat locally and damage the tube.
⑥When the power supply of the filament of the electronic tube is turned off, the water and air used as the cooling tube still need to continue to cool for ten minutes to dissipate the waste heat.
⑦ When the electronic tube is working, its anode and grid current shall not exceed the rated value. The ratio of anode and grid current should also be adjusted according to the range specified in the manual. If the ratio of anode and grid current is too large or too small, the power loss of anode and grid will exceed the regulations and damage the tube.
⑧The spare tube should be used alternately with the tube used on the equipment to prevent the vacuum in the tube from being reduced in long-term inventory.