GETTING THE MOST OUT OF VACUUM TUBES by Robert B. Tomer
You can make it through this book reading it cover to cover. It's actually pretty interesting!
Tomer doesn't waste time with equations. Instead, he writes in a language that almost anyone should be able to understand. I've had my copy for years now. It's a reprint from the Audio Amateur Press.
Vacuum tube failures. Subjective failures such as "hum" and "microphonics" are also covered
Tube characteristic variables and how the tube standards were set
Select and premium tubes are discussed
Discusses why so many tube types exist. ( back in 1960 that is...)
Touches on how to predict tube performance
Explains why some tube testers are O.K. and others are doing more damage than good
Gives a decent treatment on special purpose tubes such as voltage regulators
Methods for lengthening tube life
Offers good tips on maintenance and proper handling of tubes
The book appears to still be available at various sources.
Amazon.com for around $10
Powell's books for about $11
Tubesandmore.com for about $15
Available for free from Barnes and Noble as a "Nook Book" (eBook) download
Thanks for reading,