I have a paperback copy of this on my shelf:

"How to Test Almost Everything Electronic," by Delton Horn.

http://www.amazon.com/gp/product/083...lance&n=283155

It won't delve into obscure mysteries of vintage tube equipment, but it does
give an overview of how to use many test instruments.

Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html