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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I recently restored a Sylvania model 620 tube tester. The manual was dated 1955, so that is the approx vintage. Sylvania describes the test method as “Sylvania Composite Transconductance and Emission.” (Source: Sylvania 620 service manual, page 5). This method is not the same as Hickok’s Mutual Conductance. This is an extremely well-built tester. Construction
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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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The article provides examples of Sylvania-manufactured tubes. Sylvania was probably the most prolific American tube manufacturer, and their tubes were found packaged by many well-known USA name brands. Among the EIA codes that you will find on Sylvania-manufactured tubes are 312 and 722. Here are photographs to illustrate the wide diversity of companies that Sylvania
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It is quite common to find tubes that have a “brand name” printed on them, but were actually manufactured by a different company. Yes, you can easily find “RCA” tubes made in a Sylvania factory, “GE” or “RCA” tubes manufactured in a Tung-Sol plant, etc. So how do you know which company actually manufactured your
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