Radio Craft, Dec 1931, p. 373.
Radio News, May 1932, p. 956. (only the 4 tube model)
This is the same device (with the same model numbers) as sold by Newark.
400, 3 tubes, $29.50
440, 4 tubes, $34.50
References
Review. Radio Craft, Feb 1932, p. 480. (referred to as the S-11)
