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[julianburke]

[QUOTE=Electronic M;3253618]Zenith/rauland made their own, RCA did, and so did Sylvania. Easiest way to know who REALLY made a tube is to look up the EIA number on the label. I've seen Zenith labeled roundy tubes that had Zenith, Rauland (Zenith subsidiary) and RCA EIA codes. The RCA tube appeared to be early into Zenith selling roundys.


Many years ago the CRT's were in somewhat short supply. If you made your own tubes you were in the drivers' seat for making as many sets as you wanted. Smaller manufacturers had to depend on what ever they could get ie; Curtis Mathis and others like them. Yes, they also traded around as in contract marketing. Smaller vacuum tubes were also treated and traded the same way.