The topic of snagging old vintage radios, etc for amp components came up in a recent thread. It inspired me to reach out to a few Craigslist ads, and through those I found some local antique radio enthusiasts (and veritable pack rats) who have large stashes of great stuff for sale cheap. I am curious, however, about vetting transformers from these units. How do you all go about this? A few friendly folks here talked me through assessing voltages in the PT secondaries. I am curious how one moves from that information to determining what the unit could be used for. Is measuring current across the secondaries a necessary next step? I snagged a nice old radio chassis today for $10. It is running a 6V6-GT power tube with a 5Y3-GT rectifier and a 6AV6 (I understand this to be basically 1/2 of a 12ax7) preamp. These are in addition to 5 other tubes that I think are specific to its radio receiver. Output in an old manual is listed as 3.5 watt undistorted (I love how they specified this) and 5 watts maximum. Given the tube compliment and power range, is it basically a foregone conclusion that the PT and OT (if functional) are 5f1 or 5f2a worthy, or are there other considerations?