I just bought a couple of 811a tubes to start to experiment/build an amp. I also bought a 15th edition and a 22nd edition of bill orr's Radio handbook. Also bought RCA's TT-5 transmitting tube book. Any ideas or suggestions on what I might need or that may help me better understand tubes would be great. Got a really great deal on a pair of 4cx350A tubes as well ( I paid $30 for the pair) but the 811a's are the first leap/project.