As I advised elsewhere, you, N8FVJ should acquire books found at hamfests and start reading them. I failed to mention tube manuals. Often at hamfests, you will find for sale, old RCA tube manuals. In some of them, the first 30 pages or so are an excellent introduction to vacuum tubes and how they work. If you absorb that information, you will probably know more about tubes then 95% of all hams. Then there are extensive data entries for many tubes by type number. RCA also published a harder to find RF power tube manual (Transmitting tubes). If you see one of those grab it, but the smaller octal tubes like the 6146 are found in the more general manuals. Get several for different years because the older ones have tubes not found in the later ones. GE also published tube manuals that have information not found in the RCAs. Don't overlook a ring bound GE manual if you find one.