Tung-Sol 6SU7GTY - USA - matched pair - wartime manufacture - 6SL7GT equivalent

A matched pair of Tung Sol 6SU7GTY tubes. The 6SU7GTY designation was unique to Tung Sol. They are a special 6SL7GT, selected for having less than a 3% difference in gain between triodes for use in a special military radio application. Considered by some to be the best American made 6SL7GT variant that can be had. One of these tubes was labeled "6SL7GT" to sell into the commercial market as the "6SU7GTY" designation would have no meaning to non-military consumers.

-  Black, round plates. Brown, micanol bases. Both tubes have the same structure inside and out.

-  Likely these date to 1945 when Tung-Sol went from full round mica to the rectangular top mica. The nature of the bases is also indicative of wartime manufacture, as by the late 1940's and into the 1950's the brown color became lighter.

-  Date codes of: "322613" and "322713", which correspond to the 13th week of 1946 and 1947, respectively.

-  Tested on a calibrated Hickok TV-3 military tester and matched for dynamic gain and structure.

-  The tubes test at 1750-1750 and 1750-1750, where pass/fail is 1100 microhmo.

-  Likely new or very, very lightly used as there are no emission deposits on the top glass.