Cossor 343 Inny
Frequency Modulated Ganging Oscillator


The Oscillator and Output-Meter method of alignment served its purpose well in the days of sets using single tuned circuits. The fact is well known, however, that from the first moment that modern superheterodynes using band-pass intermediate frequency or band-pass pre-selector circuits were introduced it became imperative to recourse to the visual method of alignment. Many years' experience in aligning modern sets in production has confirmed the necessity for this change. Whilst the expensive laboratory Signal Generator and Output-Meter are still required in research work for point to point determination and absolute selectivity tests, the less ambitious service equivalents of these instruments which are generally used do not provide satisfactory results on production tests and service work. This is particularly the case when the work has to be done by other than highfy technical personnel, when the time allowed is limited, and when the fullest possible information is required from the test. These limitations of the Output-Meter method obviously increased as radio development progressed, because technical improvements in commercial radio receivers qyickly appeared with which this method could not cope in the light of the above-mentioned requirements. The Cossor Research Department had pioneered the development of Cathode Ray Tubes as far back as 1902, and the increased complication of modern Receiver technique coincided with the advent of an efficient Cossor sealed-off low voltage Cathode Ray Tube possessing the required rugged construction and long life. The recording versatility of this device was speedily applied to the solution of complex design problems, to production aligning and eventually to the service testing of receivers. The Cossor Company was, in fact, the first to employ this method in these fields, a step which has been followed subsequently by many other manufacturers and is now general. After these many years of experience it has been found possible to design and construct an equivalent inexpensive equipment comprising the present-day Oscillograph Model 339 and Ganging Oscillator model 343. These can be used with confidence by the Radio Service Engineer not only because they have been designed by a radio manufacturer who knows the real requirements of service work, but because they are a proven proposition and the outcome of years of commercial testing in the factory. The equipment fulfils a greater purpose than ganging. It can be used for a variety of tests on radio sets, and above all, the instantaneous trace of the Cathode Ray Tube furnishes the Radio Engineer with the means of actually seeing what is happening in the electrical circuits he uses, thus providing the most satisfactory means of fault tracing in radio receivers. Furthermore, the new Double Beam Tube, by serving without additional expense or duplication of apparatus, as the means of investigating simultaneously two independent effects, has provided a considerable increase in the versatility of the combined equipment as now offered to the Radio Engineer.

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Serwis i User Manual
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Serwis i User Manual
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Upload date:
17 August 2017


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