For Kim and those interested in burn in of power tubes:
Likely a University that has an engineering school would have back
issues in the Tech Library of RCA Reviews, or other old tube company
technical publications. Even the Bell System Technical Journal of the
hey day of tubes might have studied the optimum burn in of power tubes.
Some of this material also has been scanned into web pages. Focused
Google Searches should find what there is about tube handling on current
I seem to recall a "recipe" either as an email or from an email, as a
link to someone's web page.
Hopefully, someone has that bookmarked or knows where to look.
Back in the day, Eimac published technical notes on power tube use, and
some versions were even in an ad series in ham magazines.
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