Radio age (Jan 1927-Jan 1928)

©C1B 731864 RADIO AGE for February, 1927 The Magazine of the Hour 5 I_ _ wmjmM UGq Magazine (ffhe Hour B. Smith Business Manager A Monthly Publication Devoted to Practical Radio Frederick A. Smith Editor Two Tubes and Regeneration By ARMSTRONG PERRY BEFORE advising anyone to build a regenerative receiver, it is only fair to issue a warning that regenerative sets became such a nuisance, soon after broadcasting attracted the general public to radio, that the United States government called conferences in which serious recommendations were made (by manufacturers who were building other types of receivers!) that the manufacture, sale and use of regenerative sets should be prohibited by law. Such a prohibitory law might be enforced more easily than another one that has been quite a live topic of conversation for the past few years, for a government inspector with a radio compass can locate a blooper more easily than an enforcement agent can find a still. The principle of regeneration is as sound in radio as it is in religion. It must be, for one man is said to have been paid a million dollars for a patent on it and another man spent thousands in proving to the satisfaction of the courts that the fellow who got the million only copied his invention. Superregeneration will amplify energy so tremendously that a receiver using it will pick up a whisper from a man a hundred feet away and throw it back with the volume of a cannon's roar, or make the footsteps of a fly on a bald man's head resound like the ambling of an elephant on a tin roof. REGENERATION is a method of salvaging some of the radio-frequency energy that passes through a radio tube — which has no useful effect on the side where the phones or loud speaker are — and feeding it back into the grid circuit so that it increases the energy that controls the volume of the sounds we hear. Even a novice, by doing a little experimenting, can learn to use regeneration successfully. Having made the plunge into the field of multitude set construction, as far as two tubes, the constructor asks himself which tube shall be the detector and which the amplifier. If the first tube, counting from the antenna, is the amplifier, the set will have one stage of radio-frequency amplification. If the first tube is the detector and the second the amplifier, then the amplification will be of the audio-frequency variety. The builder who wants to pull in the far-away stations will find that radio-frequency amplification will give him the best chance, for the R. F. amplifier increases the weak signals more than the stronger ones. If he wants more volume on stations that can be heard with one tube, then the second tube should be used as an audio-frequency amplifier. The beginner will have better luck if he tries audio-frequency amplification at first, making the first tube the detector. Radio-frequency amplification is more difficult to handle because the filament and plate, and filament and grid, form small condensers whose capacity, small as it is, has effects that may be hard to overcome. There may be inductive effects that are troublesome also. The tube may howl at the slightest provocation and for no reason that the novice can discover. If radio-frequency amplification is attempted, it should be remembered that a potentiometer, otherwise known as a stabilizer or voltage divider, will be of great assistance in steadying the action of the tube. It should be connected across the