Today I scored some more NOS tubes, and a tester to boot! All of this was free of charge (I insisted on paying, but they would not accept)! Anyhow, this tester should be useful for testing all the NOS tubes I obtained in the last week. These include 3 new Mullard 12AX7s (10M series), 2 GE 12AY7s, some Marconi 12AX7s, a pair of Sylvania 6L6GCs, German Siemens 12AT7s, and many others! I will probably start another thread on this since some of the labeling is confusing. For example, the Mullards came in Siemens or Sylvania labeled boxes, with B & L labels, and I can't find any info about these. Also, just for my own curiosity, I would like to ID years of production, etc. (I am a very curious person!)! The biggest issue for now is learning how to use the tester. I have all the manuals, and a whole bunch of other reference data (this gentleman gave me a GE tube manual, and several others including a tube cross-referencing guide and several AVO books). As far as I know, the tester is in fine working order (even has a 3-prong plug). However, before I plug it in, I am wondering what I look for. Then, how do I go about using it? Do I just plug in a tube and "hit go?" I am nearly new to the NOS tube thing, and completely new to tube testers, so any help would be appreciated. Thanks!!!