Had to replace a 12AT7 in my tuner and this is what I pulled out. It's a Sherwood labeled Brimar black plate 12AT7 and engraved with what I'm guessing is the tube builder's initials "OS". I've never this before, but I've probably handled only a couple dozen Brimar tubes. Anyone else seen this before?
Edits: 08/18/12This post is made possible by the generous support of people like you and our sponsors:
Topic - engraved plate 12AT7 Brimar - NativePrairie 17:18:57 08/18/12 (3)