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 …
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 …
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 …
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 …
Sencore Mighty Mite solid-state tube testers (TC28 Hybrider, TC162, and TC154) are durable, easy-to-use, and test a wide variety of modern tubes (including modern sweep tubes such as #8950). They were VERY popular among old-timer technicians. For most people, they are a very good choice. Regardless of model, all the Mighty Mite solid-state models use …
