Radio Broadcast (May 1928-Apr 1929)

JULY, 1928 RADIO BROADCAST 135 -1 O No. 1 Radio Broadcast's Home Study Sheets JlUlly3 The Nature of Radio and Electricity THERE can be little doubt that radio is one of the most attractive fields for home experiment that has ever presented itself. Radio problems are not to be solved in a day; the apparatus required for intelligent experiment is not too complicated or expensive for the layman, the interesting theories involved may be mastered by anyone who cares to study; and the ramifications of radio experiment deal not only with electricity but, for example, with chemistry and acoustics as well, so the tired feeling of having solved all, is never to be experienced. Radio is closely allied to electricity, that more or less intangible force which our senses normally refuse to recognize. We cannot see it, or hear it, and are not aware of its presence unless it is in motion, doing work of some kind. And yet it is always present ready for action, to be generated and controlled by man, and at his will to spend its energy doing useful work. The radio experimenter plays with this force, and thereby finds out for himself many of the facts about the force that runs our street cars, lights our homes, transmits our messages, brings music out of the silent ether, and does innumerable small tasks that are no longer considered remarkable. To find out the most important facts about electricity and radio, one must experiment, not in a hit or miss fashion but with some object; he must have a good knowledge of the tools with which he works, and a clear picture of what happens when he uses those tools. While it must be acknowledged that many inventions and discoveries have been made by individuals who work in attics and cellars without adequate mental or electrical equipment, by far the greater part of real advancement comes from research that is intelligently planned and systematically carried out. The Laboratory Staff has planned a number of experiments which shall be described each month in Radio Broadcast, experiments which shall first be performed in the Laboratory of this magazine and which the home experimenter may repeat if he desires. These experiments deal with electricity and radio and should give the experimenter a wide knowledge and experiQ ence in radio matters. The apparatus needed for each experiment will be given in exact detail so that the experimenter can build or buy it if he desires; the exact procedure of the experiment will be followed by the results obtained, and by a series of questions or problems or suggestions for further experiment. These questions and problems are for the experimenter to answer. If he desires to send the answers he has worked out to the Laboratory Staff, they will be glad to look them over and will always be interested to know how to make the experiments more helpful. These pages are so prepared that it will not be necessary for the interested reader to repeat the experiments; but if apparatus is at hand, or if he desires to equip himself with sufficient instruments so that he too can take part in the great business of radio experiment, he will do well to carry out the procedure, or to amplify it at his leisure. It is possible of course to carry out the calculations of many experiments without actually doing them physically at a patent saving. In fact, it will always be wise to check over the data given in these pages, working out what mathematics may appear so that almost the same effect is secured as if the actual experiment had been repeated. The experimenter will need, first of all, a loose-leaf note book. Those used in the Laboratory are McM (Manhattan Stationery) ring books No. 518D. The actual make is not important so long as it is large enough to hold sheets the size of Radio Broadcast's pages. In this notebook should go these pages in Radio Broadcast which are marked on the margin ready for punching — there will be no excuse for having an incomplete file of experiments! There will be needed, in addition to the binder and these sheets from the magazine, a stock of paper to fit the binder, both blank and cross section. A good cross section paper is Keuffel and Esser No. N355-2R. It costs two cents a sheet and may be obtained from Keuffel and Esser, 127 Fulton Street, New York City. Another requisite is a good ruler, preferably a triangular scale graduated in 10, 20, etc. parts to the inch. Keuffel and Esser No. 8883 is a good one. One or more " French curves" are useful in making complicated graphs. If the experimenter feels that he can afford a slide rule, he should invest in this extraordinarily useful instrument. It is a device which simplifies computations involving multiplication, division, percentages, squaring or cubing or extracting the square or cube roots, or using logarithms. With it one can save hours of time and bother and exasperation. The one used in the Laboratory is a Keuffel and Esser No. 4053-3 costing about $8. A booklet comes with it showing exactly how to use it. Of course the calculations which a slide rule — a "slip stick" as the engineer calls it — make simple may be done with pencil and paper and — when the problem in hand requires their use — with the aid of a book of logarithms. This roundabout method requires ten times the labor. The experimenter should have a supply of pencils, pens, India ink, scrap paper, as well as a good place to work. Mathematical calculations may be carried out anywhere, so that the reader may follow this part of the experiments which will follow at his convenience. To do the actual experiments, however, in case the experiments are to be duplicated by the reader, a good light place is desirable where apparatus will not be disturbed by the domestic broom or dust cloth! A corner of the basement, the den, or attic may be used. Even the kitchen may be impressed into service with the disadvantage that the experimenter probably may have to pack up his apparatus each evening. A good way to keep your own notebook is to work out the problems or repeat the experiment on a loose-leaf sheet which is inserted directly after that clipped from the magazine. If sent to the Laboratory for checking, the problems must be on a standard punched sheet to enable us to examine them with the least difficulty and so that the experimenter can place them in the notebook when they are returned. Some Useful Tools for the Home Experimenter