I found and scanned this from 1927 GE Review. It is a very readable two part article on the workings of triode tubes of that era. It talks about spark telegraphy and some dated topics, but the general principles of tubes are very well explained, and still apply today. I didn't realize, for example, that they had thoriated tungsten filaments then. Especially helpful is the discussion on space charge, which helps explain how you can destroy emission with a gassy tube.
It has been graciously posted by Gary, W3AM, at
www.w3am.comYou'll find it in below the suggested AM frequencies chart on Gary's site, in two parts, to download as PDF. These are big files, ~3 and 5 MB each.
