This article provides examples of NATIONAL UNION-manufactured tubes. NATIONAL UNION was another quality USA tube manufacturer with most production dating from 1930s to 1950s. Their production numbers were significantly smaller than the big name brands (RCA, Sylvania, GE). The NATIONAL UNION (EIA) code number is “247″. Here is an example: (Left = Sentinel brand 6SN7GT; […]
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This post provides examples of Raytheon manufactured tubes. Raytheon was an extremely high quality USA tube manufacturer with prolific output, covering both civilian issue and a vast majority of US Military parts production. The Raytheon (EIA) code number is “280″. Here is an example: In this photo, we see three Raytheon-manufactured 6SN7GT tubes featuring Black
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This article provides examples of GE (KEN-RAD) manufactured tubes. GE was one of the most prolific tube manufacturers in US history, and many companies sold GE tubes repackaged under their own brand name. The GE factory EIA code number is “188″ and proves GE was the true manufacturer, although there are a few rare exceptions
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This article provides examples of RCA-manufactured tubes. RCA is probably the most famous tube manufacturer in US history, and many other companies sold RCA tubes repackaged under their own brand name. The RCA (EIA) code number is “274″ and proves RCA was the true manufacturer. Here are several examples: In this photo, from left-to-right, are
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This article provides examples of CBS Hytron-manufactured tubes. CBS Hytron was a very high quality USA tube manufacturer. Their production numbers were much smaller than the big name brands (RCA, Sylvania, GE). The CBS Hytron (EIA) code number is “210”. When you find a repackaged CBS Hytron tube, you will most commonly find 6SN7GT and
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