Radio broadcast .. (1922-30)

Using the "Inverse Duplex" with Various Kinds of Tubes By DAVID H. CRIMES This article, written by the inventor of the Inverse Duplex circuit, discusses, from the standpoint of practical operation, the hook-up of which the theory was explained by Mr. Charles H. Durkee in the April number. Since that first article appeared, we have been deluged with letters, some hundreds of them, asking every imaginable question about the theory, construction, and operation of the Inverse Duplex. The present article has been written by Mr. Grimes at our request, to answer many of the questions that have been asked by correspondents, and to let others know something of the possibilities of this circuit. Briefly, the Inverse Duplex is a method of employing tubes for radio and audio-frequency work simultaneously, without overloading them — the heaviest audio-frequency currents flowing in the tube where the weakest radio-frequency current is flowing. — THE EDITOR. SINCE the publication, in RADIO BROADCAST, of some of the details of the Inverse Duplex receiver1 there must have been, conservatively speaking, at least two million questions asked concerning various parts of the circuit. As a result of the much appreciated cor 1"i.3oo Miles on a One-Foot Loop," by Charles H. Durkee, April, 1923. respondence, I have learned several things concerning the operation of the hook-up which would otherwise have taken me several years! And it is the purpose of this article to give the radio fan at large some of the benefits which I have received individually from him. As with all new developments, there are many things which have to be known by the enthusiast before he cm successfully dupli THE LAYOUT FOR THE AUDIO-FREQUENCY PART OF THE INVERSE DUPLEX