Note
Radio News, Apr 1936, p. 611.
QST, Jan 1937, p. 4.
Radio Craft, Feb 1937, p. 507. (specifically called the "100 series")
QST, Jan 1938, p. 61. (see photo)
References
Brief description. Radio News, Feb 1936, p. 473.
Review. Radio News, Jul 1936, p. 22.
Lab Tests. Radio News, Aug 1936, p. 85.
Precision Controls. Radio Craft, Feb 1937, p. 468.
Fidelity Controls. Radio Craft, Mar 1937, p. 529.