ARODERN RADIO Reception - 1928 -- PREFACE The first edition of Modern Radio Reception was published in 1923 and a second edition published in 1924. This present exposition of the field of Broadcast Radio Reception issued in 1928 is an entirely revised and rewritten volume. During the past three years, broadcasting conditions are entirely different, most of the transmitters and receivers used a few years ago are now obsolete. Rather than devote space to apparatus of historical interest, this book deals principally with all the latest developments which is what the majority of the experimenters or broadcast listeners demand. To make the book most useful to the large majority of the readers it has been made as non-technical as possible, the mathematical equa- tions confined to simple examples, and the descriptions of the apparatus given in an easily understandable manner. Several thousand owners of radio receivers designed by the writer have offered suggestions which are covered in this book and the author wishes to express indebtedness for their assistance and also from the following firms among others General Radio Co. Institute of Radio Engineers General Electric Company E. T. Cunningham Inc. A. H. Grebe Co. NEMA Standards Weston Elec. Inst. Co. Western Electric Co. Ward Leonard Electric Co. Readers who are seriously interested in the future of the radio field should join the Institute of Radio Engineers. This is a non-profit organization which includes in its membership all the leaders of the radio industry. Papers are issued monthly covering all the latest devel- opments in radio in the form of Proceedings of the Institute of Radio Engineers. In addition to the main meetings in New York there the Sections in Toronto, Chicago, Middletown, Conn., Los Angeles, Phila- delphia, Rochester, San Francisco, S.eattle and Washington where monthly meetings are held. Further information can be obtained by writing to the Secretary I.R.E., 37 West 39th Street New York City. CHARLES R. LEUTZ. Radio Reception CONTENTS Radio Laboratory Apparatus Radio Receivers JVe5tern Electric Srlper-Heterodyne rele Sq lichropllase lraisoceatiic Sil1,cr Ghost 1.1-ansoccanic Phanton Frequency Changers I-C Current Supplies L Current Supplies Short a c Rcccption Broatlca5t Reception Radio Tube Data Radio Standards and Definitions CHAPTER I RADIO RECEPTION The actual manner in which the transinitted electrical signal travels from the transmitting station to the receiving station is a highly technical discussion. There .are several different explanations and these theories vary with the different wavelengths propagated. The main consideration from the receiving standpoint starts with the signal reaching the antenna. ANTENNA An antenna is usually referred to as the aerial wires, lead-in and grouncl system complete, the aerial is simply the elevated wires of this system. For reception there are three distinct types, vertical. horizontal and inclined aerials. During a considerable amount of exlerimenting it has been found that the height of the antenna is the most important consideration, and will result in collecting the greatest amount of received signal energy. In technical terms, engineers always refer to the effective height of the antenna, roughly this is the average height from the ground. For example a vertical antenna 100 feet high -ould only have an effective height of approximately 50 feet...