... 2.Excellent resistance of burst. 3.15years usel Solar Vacuum tubesJust like an automobile engine, the computer CPU,Evacuated ... . Evacuated tubes have already been used for years in USA,Germany, Australia, France, Japan, Canada, China ,the UK, Chile, Peru, ... attributed to DC magnetron sputtering technology, makes the highest of vacuum tube working temperature as high as 300°C, effectively preventing ...