57T250

Pages 762 and 763 of the Fall 1929 issue of the Sears Roebuck catalog lists Silvertone tubes for the first time, with a totally new type number, for example 57T250 = UX250. Research has not yet provided a manufacturer of these tubes or location of a factory and Tynes "Saga of the Vacuum Tube" page 362, states "No information available" for Silvertone. It is presumed that these tubes were made by the Sonatron Tube Company, with offices Chicago and in New York and it is also known that Sonatron acquired three smaller companies in 1929, before they themselves were acquired by National Union in September 1929 (Tyne page 359). Silvertone tubes continued to be available for some years and tube boxes with both Sears Roebuck and Silvertone printed on them are relatively common in the US. Sears Roebuck Archives states that the company "ended its association" with Silvertone (radios and or tubes is uncertain) in 1972.