Quote:
Originally Posted by jr_tech
All tubes leak, but the barium surface can insure many years of decent vacuum.
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I have never heard this before. Now it is common knowledge that some of the early metal/glass tubes (19AP4) developed leaks over the course of many years, but I am compelled to ask the basis behind all vacuum tubes leaking when there are so many around from the 40s-60s that are as strong and void of air or gas as they were when new.
If they do leak, then it must be immeasurably slow. Too slow for our lifetime. My 1920s radio tubes (O1A and the like) are holding up well too. This might be an interesting topic.