Tyne "Saga of the vacuum tube" page 351: Sold by Export Radio Products Co.

The earliest known Amplion tube is a type D detector of 1923/4. This was apparently sold by the Export Radio Co. but no information on this company has been found.

The" Fitchburg Centinel" newspaper of Fitchburg, Massachusetts of July 21, 1931 has an advertisement for nine of the main receiving tubes available at the time. The advert states that the tubes were made for the Amplion Corporation of America by one of the World's leading tube manufacturers. The tubes were distributed by Parke Snow Inc, a general merchandising and department store located at 540 Main St, Fitchburg. This store was incorporated in 1919. This would be only one such distributor of Amplion tubes. No information or other advertisements for this tube has been found from 1924 to 1931.