The main purpose of these Articles is to show how Engineering Principles may be applied to the design of crystal radios.  Measurement techniques and actual measurements are described.  They relate to selectivity, sensitivity, inductor (coil) and capacitor Q (quality factor), impedance matching, the diode SPICE parameters saturation current and ideality factor, audio transformer characteristics, earphone and antenna to ground system parameters. The design of some crystal radios that embody these principles are shown, along with performance measurements.  Some original technical concepts such as the linear-to-square-law crossover point of a diode detector, contra-wound inductors and the 'benny' are presented.

Please note:  If any terms or concepts used here are unclear or obscure, please check out Article # 00 for possible explanations.  If there still is a problem, e-mail me and I'll try to assist.
Second note: The two dates following the Article titles are, respectively, the original publication date and the date of the last revision.