Image: Crystal radio receiver from wireless era

Description: Early crystal radio receiver built by a radio amateur in Belfast, Ireland, during the pioneering wireless telegraphy era of radio around the first decade of the 20th century, showing examples of the early electronic components used. From a 1914 radio book. This example is a sophisticated inductively-coupled type, with an air-core antenna coupling transformer (called a loose coupler) to improve selectivity (Q factor) by adjusting the inductive coupling. This was used to receive long wave (148 - 283 kHz) radiotelegraphy broadcasts. Alterations to image: Added colored labels. The labelled parts are identified on p. 264 of the source text as:
Title: Crystal radio receiver from wireless era
Credit: Downloaded 2009-11-14 from Rupert Stanley (1914) Textbook on Wireless Telegraphy, Vol. 1, Longmans Green & Co., New York, p.265, fig. 151 on Google Books
Author: Rupert Stanley
Permission: Public domain in USA - published in USA prior to 1923
Usage Terms: Public domain
License: Public domain
Attribution Required?: No