Crystal Control

Radio Record, Volume II, Issue 1, 20 July 1928, Page 4

Crystal Control

_ EFFECTIVE AT 2YA. FIRST IN AUSTRALASIA. QTATION 2YA is now equipped with Piezo Crystal control, and is believed to be the first station in Australasia to be so equipped. Mr. J. M. Bingham, the company’s engineer has been in Wellington fo: several days past working on this equipment. The work is mow completed, and the station is now transmitting on the new system. ‘This is a marker advance and demonstration of the de‘sire of the company to keep the sta: tion equipment in the forefront of ‘technical efficiency. : ‘With the. conventional valve oscillator there was reason to suspect that the frequency of the wave would ‘be liable to be varied by the impressed speech and music as well as_the amplitude of the wave. For best operation the wave lerjzth should not vary-only the power of the station be varied by the speech or music. If a station suffers from frequency as well as amplitude, modulation, it is- bound to suffer from a certain amount of lack of clarity. Under crystal control the possibility of frequency variation is reduced to an absolute minimum, and th ewave put out has only the amplitude variation which is ‘the ‘objective desired. — The frequency of 2YA, it may be stated, is 713.9 kilocycles. As showing how up-to-date 2YA is now in comparison with other stations, we append a brief reference to crystal control from an American authority which is just to hand by the American mail. GPECIAL piezo oscillators, which will hold a station so close to its frequency that several such stations can operate on the same wave length with-

out interference, is @ possibility of thie very near future, according to Dr. J. H, Dellinger, of the radio laboratory of the United States Government Bureau of Standards, "Radio frequency standardisation, of hithertofore laboratory character only, has been of first importance in reducing radio interference," says Mr. Dellinger, "The recent International Radio Conference recognised frequency as the corner-stone in the radio structure by devoting its major attention to a frequency allocation to provide for the orderly development of all radio services. "Because of the increasing use of all ayailable radio channels, particularly those for broadcasting, and the very high frequencies, the requirements of

frequency measurements are a hundred times more rigorous than they were five years ago. The perfection of standards and measurements to the necessary ac‘curacy requires the most intensive work by the Government and by yarious large organisations to produce standards and instruments that can be used to keep radio stations each operating on its own channel. This development has been facilitated by a special cooperative plan organised by the Bureau of Standards a year ago involving the Commerce, War and Navy Departments and several large American electri and radio companies. "Piezo oscillators are now available to hold radio station frequencies extremely constant. For instruments of this type equipped with temperature control, national and international comparisons have shown that they are reliable to a few parts in 100,000. "This brings in sight the possibilitiy of the use of special piezo oscillators in broadcasting stations which will hold the frequency so close that sereral such stations can operate simultaneously without heterodyne inter- | ference on the same frequency."