| 摘要 |
PROBLEM TO BE SOLVED: To provide an apparatus for easily estimating the life of a vacuum tube under environment of a large source change and a high-frequency heating apparatus with the apparatus. SOLUTION: This apparatus is fundamentally comprised of a heater supply circuit part 10, which is a power source for generating an a.c. to be supplied to a filament 31 of the oscillating tube 3 and which has a function of controlling the effective values of a voltage and a current of the a.c. to constant values, a filament voltage/current detection part 30 for detecting effective values Ef and If of the filament voltage and the filament current of the oscillation tube 3, a filament resistance-operating part 41 for operating a filament resistance Rf (=Ef/If) of the oscillating tube 3, based on the detected result of the filament voltage/current-detecting part 30, a warning part 42 for warning and outputting that the oscillating tube 3 nears the end of the life or has reached the end of the life, when the filament resistance Rf is not larger than a set value Rb, and a life-estimating and outputting part 50 for outputting the change with time of the filament resistance Rf.
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