The how and why of radio apparatus; a treatise on the principles underlying the operation of wireless transmitting and receiving instruments, with an ... "Calculation and measurement of inductance,"

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1920 Excerpt: ... novel form of monotone receiver is illustrated in section at Fig. 11, this particular type having been used with great success in submarine telegraphy and telephony. It was devised by a New York electrical engineer, Mr. Christian Berger, inventor of the submarine telegraph system now used on ocean-going vessels and submarines. This receiver is similar in design to other electro-magnetic types, and is provided with a permanent steel magnet. The novel feature of this receiver which puts it in the monotone class lies in the design of the special diaphragm. This diaphragm is comparatively heavy, even as thick as one-quarter of an inch in some cases, and as the reader will observe, it is not supported in the ordinary manner between the shell and cap of the receiver, but is mounted on its central axis upon a rigid stud secured to a brass block between the magnet poles. When a current of the proper periodicity or frequency is passed through the windings of this receiver, and providing the proper diaphragm, tuned to this exact frequency is utilized, then the fullest response possible with this form of instrument will be had; the tuned, tempered steel diaphragm of the bell type, vibrating at its own natural period with a maximum amplitude. Many unique modifications of this principle have been devised by Mr. Berger, and with this form of diaphragm the purest note imaginable is obtained. At Fig. 12-A, there is illustrated the "Fessenden" heterodyne receiver which will translate and reproduce signals from an undamped wave radio station by the well-known principle of beats. Thus if an incoming signal has a frequency of fifty thousand cycles per second and this current is passed through a light magnet coil secured to the diaphragm of the receiver, while an aux...