Audio synthesis via vacuum tubes/Using sheet-beam tubes (view source)
Revision as of 18:39, 19 July 2022
, 1 year agoText replacement - " (archived) by Eric Barbour, 1997, with permission of the author" to " by Eric Barbour, 1997, with permission of the author - archived"
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'''Using sheet-beam tubes''' has no parallel in the transistorized age. Between the mid 1930s until integrated circuits became commonplace in the 1960s, special electron tubes were designed to take advantage of specific effects of electron-beam ballistics. Essentially, these tubes were "integrated circuits" before the term even existed. And they did fairly complex things using very simple designs.<ref name="usbdt">[https://web.archive.org/web/20171020033858/http://www.cgs.synth.net/tube/beam.html Using special beam-deflection tubes]
== Background ==
[[File:cgs_photo_6BN6.jpg|162px|thumb|right|6BN6 sheet-beam tube]]In 1954, the expanding need for single-sideband communications equipment caused RCA to introduce a special tube for use as a balanced modulator. The 7360, the first of the "sheet-beam" tubes, is often seen in Collins and other two-way radio equipment of the period. Because there are obsessive Collins collectors, 7360s have become scarce and costly. However, the tube manufacturers were always looking for new markets that could be satisfied with tubes made on their existing production equipment, especially the huge television business. So lower-cost versions (with a different pinout, to prevent cross referencing) of the 7360 were made, primarily under the numbers 6AR8 (believed to be a Tung-Sol product), 6JH8 (Sylvania) and 6ME8 (apparently GE). These tubes were almost identical to each other, even though they were made by different factories--typical of the tube business--standardization was forced upon them by TV set manufacturers, who wanted to use these beam tubes as video demodulators. Another family of sheet-beam tubes was the 6HW8, believed to be European in origin and quite different in pinout from the others. And there's the obscure 7763, having yet another pinout.<ref name="usbdt"/>
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