QST Aug 1935 p. 78.
The M series model 10 Sargent receivers were intended for the marine market and tuned from 200 kHz to 21 MHz. The four-tube plus rectifierregenerative sets sold for $39.50. The D in the nomenclature indicated that it was designed to run directly from a ship’s DC power.
Review: Radio, Aug 1935, p. 23.