Two, new in box, Sylvania 5692 tubes, the long life/high reliability 6SN7GT. The 5692 tube had two distinct designs, one from RCA and a later one by CBS/Hytron-Sylvania (originated by CBS-HYtron and tolling purchased by Sylavania after CBS-Hytron stopped manufacturing tubes in 1962). Other manufacturers offered the 5692 for sale, such as GE, Westinghouse, Raytheon, etc...but were made by one of these two concerns. The RCA design has the red base, the flat (no sheen) black plates, unique mica design, and the octagon enveloped 5692 designation on the side of the bulb. The CBS-Sylvania design utilized glossy black plates, the etched designation is found at the top of the bulb, and they had brown micanol bases. Brown micanol bases, flat black plates, reinforcing rods. The 5692 is of course the ruggedized, low microphonics, low noise, high reliability, long-life version of the 6SN7GT tube and can be used in applications calling for the 6SN7GT. Tested on a Hickok TV-3 military tester that has been calibrated, just to make sure. Firm bases, excellent silvering. Tubes are matched for dynamic gain and structure- test at 3125-3062, 3125-3062 where pass/fail is 1625 micromho. Tubes have the same structure inside and out, having matching date codes of November of 1966. 

Many other lots of tubes for sale this week.

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