Radio broadcast .. (1922-30)

Concerning My Invention— The Audion 253 seemed to have fallen off in their programmes, sending mostly phonograph music. None of their transmitters were standardized 'products, and they seemed to have great trouble in maintaining good modulation. Commutator hums, ripples, blasting microphones, etc., were very troublesome. It was found that the by-laws called for a go-day lapse of time before the results of a new classification would be felt. A station must give 3O-days notice of its demand for reclassification, thirty days would be allowed for the classification committee to report, then another thirty days for the new classification to go into effect. This seemed to spell doom for the radio listeners-in, until the new "Class B" licenses were announced by the Department of Commerce. One newspaper, an automobile house, and a religious institute have applied for this license, which calls for rigid examination of the instruments used, a minimum power of 500 watts, and careful selection of programmes. The newspaper has completed the installation of a Western Electric Company 5oo-watt set and had its grand opening November 2nd. The others will also be ready soon. These three stations will operate independently of the Association and must divide the time equally. Concerning My Invention — The Audion By LEE DE FOREST October Twenty-fifth 1922. EDITOR, RADIO BROADCAST, Garden City, Long Island. DEAR SIR: My attention has recently been called to an article published in the RADIO BROADCAST by Professor J. H. Morecroft under the title " What Every One Should Know About Wireless and Its Makers." In this article I find mention of my invention of the Audion and several references to the Audion which are by no means in accord with the facts. I am persuaded that Professor Morecroft in no way intended to do an injustice to me or your readers, and will himself in all fairness welcome a brief statement on the genesis of the Audion. From time to time the statement has appeared, as in the case of the Morecroft article, in effect that in my invention I contributed the grid to a rectifier or two-element vacuum tube, and thereby created the Audion or the three-electrode vacuum tube, the present heart and soul of radio communication. What could be more simple in the way of an explanation? What at the same time further from the truth and still further from a knowledge of the simple facts of radio principles? Professor Morecroft says: " It seems strange that Fleming did not at once jump to the idea of the Audion, but the history of science is full of just such occurrences — a worker on the point of making an important discovery, yet missing it by the merest chance." Had Fleming thought of the grid, had he inserted it in the Edison Valve, he would have had exactly what he did have, a rectifier — but with a grid-shaped anode —nothing more. Had I come to this stage by the route Fleming followed, I should have done exactly as Fleming did— missed it exactly as he missed the Audion. To recognize that the anode battery circuit is as essential a feature of the Audion as is the third electrode, that by virtue of this local energy alone is the Audion a relay device and therefore an amplifier of transcendent value, instead of a> mere rectifier of received alternating current — seems such a simple proposition, so self-apparent, that I have always been at a loss to understand why any one should fail to grasp it. Yet such is the very common position of many writers : " The Audion is the Fleming valve with a third electrode." "Its inventor improved the Fleming valve merely by the addition of the grid." I doubt if such misleading stupidities were elsewhere ever preached in the history of the electrical art. Add a third, or any number of electrodes to the Fleming valve and it remains the Fleming valve — a mere rectifier, possessing the utility of the rectifier and nothing more.