Radio today (Sept 1935-Dec 1936)

the pattern and thus deliver a more perfectly serviced system to the customer, is it not preferable to teach the subject, so that the value of the test may be realized, rather than not teach the subject, not make the test and not secure the information? It is a perfectly normal request to make of the service industry, that it become technically more proficient. That it obtain a more thorough grounding in radio technique in order to be able to employ testing equipment which is on a par with modern radio receiver development. The proper application of the cathoderay oscillograph places servicing capabilities at least close to, if not on the same level with modern receiver design. Complicated stuff It is impossible to deny that the servicing industry, being called upon to work on highly complicated apparatus, requires equipment which will enable operation upon this complex interlocked system with the ease and accuracy that was possible with the simpler receivers of years ago. Design engineers incorporate special dual channel audio systems in the effort to raise the standard of tone quality. . . . What apparatus is available for the testing of such system by the service group? More and more of the receivers placed in the field contain specially filtered circuits in the speaker systems. What apparatus is available to the service group for the testing of such systems? Phase inversion systems were incorporated by design engineers, yet no equipment was developed for the simple and rapid methods of determining if that which the design engineer desired, was being accomplished in a service receiver. Transmitter power has been increased all over the country. Receivers have been made more sensitive, yet very little attention, if any, has been devoted to troubles relating to these items in certain parts of the receiver. What is taking place in the oscillator system of a superheterodyne receiver? Can one assume that if the static operating potentials are correct, the oscillator output is correct? . . . Can one assume that since the static operating potentials are correct, that i-f amplifiers provide the correct gain and are not overloaded? We recognize that if service tests are made too elaborate, the possibility exists of miscomprehension of the significance of the tests. ... If that is one of the reasons why the cathode-ray oscillograph is tabooed by some, then the problem at hand is the education of the servicing industry to realize that its function is the maintenance of radio receivers and allied units and not criticism of the systems. Everything points to even greater complications in radio receivers of the future. Who knows the extent of the complexity of the future television receiver? . . . Now is the time to start the education of the service field in anticipation of future requirements. It has been said that some instrument manufacturers looked askance at the cathode-ray oscillograph, because they felt that it would provide a means whereby service men would be able to determine the efficacy of such units as oscillators. That may be true. ... So what? ... Is the answer the continuance of the manufacture of equipment which may be subject to such criticism, or is the answer found in the changing of the design, so that it meets present day requirements. It has also been said that instrument manufacturers did not look with favor upon the cathode-ray oscillograph because it would replace certain units. In our estimation that viewpoint is wrong. Practically all existing service equipment, with the possible exception of the output meter, is related to static tests. The cathode-ray tube is essentially a dynamic testing device. That it may eliminate the output meter is a possibility, maybe a probability, but even if it does, the instrument manufacturers will not suffer. The exploitation of the cathode-ray oscillograph is going to mean the sale of audio oscillators, frequency modulators, etc. ... In the long run, the instrument manufacturers will gain, instead of losing. Costs money We do not hesitate to make this statement directly to the service fraternity. It is not a matter of recommending increased financial expenditures on the part of the service group. Such apparatus is required for the correct application of the cathode-ray oscillograph and for the completion of service tests comparable with modern radio receiver design. The day is gone when knowledge alone will bridge the gulf between modern radio receiver design and servicing capabilities. Equipment comparable with the work to be done and with the speed of operation required, is the order of the day. . . . The cathode-ray oscillograph is the first of these devices. . . . Many more will follow. 5*§L smooth Yes sir . . . he's a smooth article . . . and that's why SERVICEMEN and Experimenters everywhere pin their faith on CENTRALAB Controls. Smooth . . . of course . for the Centralab Radiohm employs that famous patented non-rubbing contact that never seems to wear out and gives a replacement service that invariably works "better than ever before." and you don't need a big stock to be able to service practically any job. Write or see your jobber for the new, revised, accurate CENTRALAB VOLUME CONTROL GUIDE f&ery Radio Service Man ffi£$ skmtld btamtmbirofrfu Wtnstauu el -B^d-i Strr^a flit" ■ CENTRALAB'S smoothness results from the patented CENTRALAB non-rubbing contact whereby a strip of polished metal rocks on the resistor so that the only rubbing action is between an oilless wood bearing and the polished metal. Central Radio Laboratories Milwaukee, Wis* Manufacturers of CENTRALAB RADIOHMS AND CENTRALAB FIXED RESISTORS Gen ■ tj September, 1935 43