Radio today (Sept 1935-Dec 1936)

SERVICING — JOHN F. RIDER (Continued from page 40) 'ATTENTION7 DEALERS DISTRIBUTORS And complete line of ''Quality'' Con so 1 e s , Table Models arid Compacts with new characteristics and amazing performance at a price advantage over all competition. METAL TUBES INTERCHANGEABLE WITH GLASS THE "HOT" LINE THIS YEAR THAT IT WILL PAY YOU TO INVESTIGATE Write for open territory INTERNATIONAL RADIO CORP. ANN ARBOR, MICHIGAN, U.S.A. "Originators of AC-DC Radio " ... It hangs on and hangs on — but eventually it goes. . . . Too many servicemen lack the courage to turn a job down — to tell Mr. John Public that the price is so and so and that's that. . . . The service industry, like any other industry, is entitled to a respectable income, so that the members can live like human beings. . . . Courage is what is needed ! . . . Courage to refuse to do business at a loss ! . . . The courage to charge a profitable price! Cathode-ray Opinion is divided concerning the suitability of the cathode-ray oscillograph for use in the radio servicing field. We hail its exploitation as the start of a new era in servicing, with far-reaching influence. The "nays" claim that the instrument belongs in the laboratory and that the type of information made available through the application of the oscillograph is not necessary for successful servicing. As evidence, there is offered the spectacle of many years of servicing without the use of oscillography. We cannot agree with these opinions. We have worked with the tube for more than nine years and the past eight months have been spent in a concentrated comparison of its merits during service operation, as against the usual routine mode of operation utilizing conventional apparatus. We have been firmly convinced that the introduction of the cathode-ray oscillograph as a servicing tool will prove beneficial to the service technician as well as the radio industry at large. The cathode-ray oscillograph is not a highly technical device. Its operating principles can be comprehended as readily as the operating principles of any other testing unit. As to the value of the information which can be secured by applying the tube to practical use, it is our opinion, for what it is worth, that such information is extremely essential to satisfactory servicing and to the advancement of the servicing art on the whole. It is freely admitted that the tube has use in the design of radio apparatus. As such, it must have use in the servicing of radio apparatus, in order to establish the existence of the conditions which were originally planned into the receiver or amplifier by the design engineer. It has been said by those who are not in favor of the cathode-ray oscillograph as a serviceman's tool, that interpretation of the images is not within the realm of the servicing field. Particular reference is made to audio waveform patterns. The statement is true at this time, but there is no sensible reason why the statement should remain true. Technical advancement of the servicing industry is just as important as advancement in radio receiver design. However, it is admitted that the waveform test to establish distortion is an excellent means of checking the operation of the receiver. If this be true, why should the service industry be penalized, because during its routine study of radio principles, the subject relating to the images, which can be developed upon the cathoderay oscillograph screen, was, shall we say, neglected or considered but briefly. To neiv heights Why should the radio industry develop equipment "down" to the servicing level? Why not develop apparatus which will bring the servicing industry "up" to the level of modern radio receiver design ? An examination of servicing literature issued during the past ten years, shows almost a total absence of references to the audio system in the receiver. Perhaps this was due to the relative simplicity of the audio channels used in receivers, but now that audio channels in radio receivers are very much more complicated and public address amplifier manufacturing is an important industry, closer attention must be paid to what takes place in the audio part of the receiver. Comprehension of the significance of waveforms is just as important as the function of the AVC system. It is a well recognized fact that a substantial amount of distortion may exist in a receiving system, or for that matter in an amplifying system, due to any one of a number of causes, related to dynamic rather than static conditions, which will not be evident to any but the critical observer. That, however, is not justification for declaring that receiver system or amplifying system to be satisfactorily serviced. The serviced system should be in perfect shape, without any question of operation left in doubt. If the audio waveform test is valuable to the man who can interpret 42 Radio Today