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Collecting the greatest tube ever made: the 201 amplifier.
In production from 1920 until the mid 1930s, there was never a tube with more variety, or longevity.
It's fair to say that the 201a was behind every radio in America for almost a decade. Many of these brand sold 199 & 200 tubes also.
See these pages for RCA 201 tubes
Index of (330) non-RCA '201' tube brands.
Patterns have emerged, indicating that there were three main periods of boom & bust. I named these as best I could, considering the approach used by the comic book industry which set the bar creating a taxonomy extraordinaire:
- Golden Age of Rubber Stamping: where any unmarked or repaired tube could have a rubber stamp label on the brass base and be called a 'manufactured' tube. Of course, someone had to be making the actual tubes...
- Silver Age of Label & Box: large efforts were made to create alluring brands and merchandizing. The race for supremacy was on, though in general all of the tubes performed the same, or slightly worse than the baseline RCA 201a tube.
- Bronze Age of Licensing: the last of the bootleggers were chased away or sued into oblivion by RCA. Now every average Joe company with a brand wanted a radio tube with their brand on it! Most found that the market was saturated, and without understanding the upcoming shifts in technology to A/C power tubes and an economy now in a depression, many unloaded them to surplus stores in the 1930s, where the price fell to 49 cents