Radio age (Jan 1927-Jan 1928)

20 RADIO AGE for October, 1927 DX Reception Record We have an interesting and convincing letter from Mr. John White who believes tie holds the world's record for DX reception on regular broadcast frequencies. He has submitted for our examination a photograph of letters and cards varifying his ■reception of broadcasts from 4QG, Queensland Radio Service station at Brisbane Australia on 385 meters, 3AR at Mel'bourne, Australia, broadcasting on 484 ■meters and using a power output of less •than one kilowatt (the station output, acxording to Mr. Whites letter of varification which he received from Australia, is now five kilowatts. This should be good :game for DX hunters) ; 2FC Sydney, Australia, on 442 meters, EAJ7 at Madrid, Spain, on 372 meters, OAX, Lima, Peru, ■in South America, broadcasting on 380 meters, and of course the west coast stations. All the stations were picked up in Brooklyn, N. Y., where Mr. Whites lives, during the winter of 1926 and 27. He writes, "2FC, Sydney, Australia, was picked up by me the second time on Sunday morning, June 5, 1927. Held him from 3 :07 a. m. to 3 :20, then from 3 :40 till 3:58." The letter of acknowledge■ment from 2FC varified the part of the •program picked up. Mr. White attributes his successful DX reception to the efficiency of his receiver which is an ordinary tuned radio frequency type. Four stages of tuned r. f. and a detector and two stages of transformer coupled audio frequency amplification comprise the set. However, each stage of r. f. is well shielded in rolled copper cans measuring 9x6x6 inches each. Every precaution was taken to minimize interstage coupling and to keep the resistance of the coils low. In each can is a variable condenser, a tube, r. f. transformer, and two by-pass condensers, 1 ■m. f. each. One by-pass condenser is connected across the filament and the other from the B side of the transformer to neg. filament which is grounded to the can. It is pointed out in Mr. Whites letter that absolute shielding is important in making the set highly efficient, not a single opening should be in the cans to permit any leakage of energy; also the r. f. transformers should be at least V/2 inches away from any part of the can. A variable resistance in the B battery supply lead to control the current to the r. f. tubes is used as a volume and oscillation control in the set. Mr. White stresses the fact that his receiver employes nothing unusual, only care in building the set has made it perform so remarkably. If anyone has a better record than Mr. "White for DX reception in the United States or Canada it will be interesting to hear about it. With much of the former congestion removed and the excellent stations recently installed in different parts of the world there are new possibilities for receiving foreign stations here in North America. Three New Radio Books Several new books treating different phases of radio and the industry, have been published recently. Among them is the Drake's Radio Cyclopedia by Handly, a volume to provide the non-technical man with ready reference work of practical usefulness in solving their problems with radio receivers and reception. The arrangement is alphabetic, each article being complete in itself with cross references to all related subjects. The subjects are treated in a manner easily understood by the layman, with material that is useful to any experimenter or set builder. Practically every phrase and term in the radio category may be found in the reference tables. Subjects such as rejuvenating vacuum tubes, locating trouble in a receiver, etc., are treated with completeness,. as well as instructions for building equipment and receiving sets. The book covers more than 1,500 subjects, with illustrations, circuit diagrams, constructional layouts and graphic curves. Another book is "Principles of Modern Radio Receiving," by L. Grant Hector, Ph. D., Assistant Professor of Physics, University of Buffalo. Modern theories on the propagation of radio waves through space, the electron theory and the theories of practically all of the new circuits and methods of receiving radio intelligence, are discussed in a technical but simple fashion which can be understood by most people interested in the business and technical progress of radio. None of the subjects is treated mathematically, except for a few simple algebraic equations. New circuits and theories about which there has been much controversy in the past are stated in an authoritative and convincing manner. The contents of this book were compiled by a physicist who has gone into extensive research to obtain accurate facts, and the material is not mere quotation of general beliefs. Every circuit from simple tuned detector circuits to superheterodyne and the most complicated of balanced r. f. circuits are described in detail. The Burton Publishing Co. put out this text. A book dealing with an entirely different phase of radio is that written by Stephen Davis of the Department of Commerce—namely The Law of Radio Communication. Since the present radio laws are so new the discussion is of abstract principles. Cases paralleling those which might arise in radio broadcasting litigations are cited to illustrate the judgment of the law. The book explains clearly the rights of the broadcaster and the listener from the view point of the judge and logical reasoning. The Linthicum Foundation prize by the Faculty of Law of Northwestern University was awarded to the author who was formerly Associate Justice in the Supreme Coun of New Mexico. The publishers are the McGraw-Hill Book Co., Inc. Radio Warns of Quakes A New Jersey radio amateur, Mr. William Andrew Mackay, believes that he has discovered an advance indicator of earthquakes in the form of some internal disturbance of the earth's crust evidenced by an alteration of radio conditions. Mr. Mackay's radio receiving apparatus is located on top of the Palisades of the Hudson, the high cliff of basaltic rock that borders the Hudson River opposite to New York City. This basaltic rock contains a high percentage of iron and is more highly conducting for radio waves than are ordinary rocks. Mr. Mackay finds that occasionally the tuning constants of his radio receiver alter unexpectedly, in much the same way as they might if the electric condition of the rock beneath were changed. This alteration of radio conditions is invariably followed within a few hours, Mr. Mackay reports, by a severe earthquake somewhere on earth. His radio apparatus served this kind of advance notice, he states, of the unusually severe earthquake in western China in May, of the Jerusalem earthquake in July and of five other severe shocks within the past six months. The warning is not invariable, some severe earthquakes having occurred without any detected alteration of the radio conditions. Certain common rock minerals, notably quartz which is the commonest of all, alter their electrical conditions when compressed or stretched. Geologists do not consider it impossible, therefore, that the state of stress in the earth's crust preceding a severe earthquake might have an effect on earth electricity, perhaps detectable in the way that Mr. Mackay has noticed.