Radio broadcast .. (1922-30)

FIG. I A rear illustration. By means of small bushings, the audio-frequency transformers are underslung from the bottom of the shelf. In order from right to left the tube sockets are, first audio-frequency amplifier, radio-frequency amplifier, detector, and the last two are the two parallel tube sockets of the second stage audio amplifier Improved Five-Tube Receiver for the The Crystallization of Modern Improvements in Receiver Design— Especially Arranged for Ease of Assembly and Operation By ARTHUR H. FULTON, Jr. ALONG with the developments in /\ receivers to be made public for £ \V the fall radio season comes one which, in the estimation of its designers, is very high up in the scale. A great deal of time and study and many hours have been spent in the laboratory to produce a five-tube receiver — improved electrically especially in the unseen parts that are so important — that would give to the inexperienced constructor a receiver which would contain the best results of design and at the same time have a finished commercial appearance. A receiver has been designed which is very easy to assemble. All the constructor needs is a soldering iron, a few other tools, the parts, and the ambition to complete the job. The term assembly is used advisedly because it can hardly be said that the receiver to be described entails either elaborate construction or detailed layout, dimensioning, or the necessity of machine shop equipment. Electrically, the circuit embodies and incorporates every important and worthwhile refinement of control and accuracy of coil design that can be approached in factory-made jobs. Here is a receiver employing a tuned, neutralized radiofrequency amplifier which has unusually CT* HERE is a story behind the development of the receiver described •*• in this article. It was felt that there were a large number of radio enthusiasts, not especially gifted mechanically, who would welcome the design of an outfit which would take the guesswork out of home receiver construction. It would be possible, thought the designers, to produce a highly efficient five-tube non-radiating receiver embodying all the best points of the Roberts Knockout receiver — which, month in and month out, continues to be the most popular receiver for home construction in use in the United States to-day — and to select a group of the best parts obtainable on the market, even to the panel. So the result is a design which we can heartily commend to any constructor who wants to build an efficient receiver with as few mechanical difficulties as possible, and who, when the thing is completed, will have a set whose appearance is as finished as a factory-made product. — THE EDITOR. high "gain", a regenerative detector followed by a straight stage of audio-frequency amplification, and that in turn followed by a special power amplifier consisting of two tubes arranged with their elements connected in parallel. No reflex feature is employed in the circuit, which sets this design off from the conventional Roberts Knockout circuit, which is, in many ways, similar. The high degree of selectivity and sensitivity of the five-tube set may be attributed to these modern improvements and changes. Going one better than the orthodox kit idea, the designers of this receiver so arranged its construction that with the aid of a basic unit consisting of the panel, shelf, and miscellaneous hardware, it is possible for trie builder to patronize his local radio dealer in the choice of the various other elements necessary for the construction of