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Radio Engineers, Proceedings of the Institute of

Issue 2 • Date Feb. 1930

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Displaying Results 1 - 25 of 28
  • [Front cover]

    Page(s): c1
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  • Future Events

    Page(s): c2
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  • Contents

    Page(s): i
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  • General Information

    Page(s): ii
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  • Suggestions for Contributors to the Proceedings

    Page(s): iii
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  • Institute sections

    Page(s): iv
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  • Geographical Location of Members Elected January 8, 1930

    Page(s): v - ix
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  • Applications for Membership

    Page(s): x - xi
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  • Officers and Board of Direction, 1930

    Page(s): xii
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  • Committees of the Institute of Radio Engineers, 1930

    Page(s): xii - xiv
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  • Lee De Forest - President of the Institute, 1930

    Page(s): 208
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  • Institute news and radio notes

    Page(s): 209 - 219
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  • Errata

    Page(s): 219
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  • A New Transformation in Alternating-Current Theory with an Application to the Theory of Audition

    Page(s): 220 - 230
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    A mathematical transformation of the elements of an impedance, called a j-transformation is considered whereby the complex impedance of each of the constituents is multiplied by j, j2and j3and thereupon the physical meaning of such a transformed system is investigated. Thus new circuits can be derived from known circuits and special properties of the former are transformed into new special properties of the latter. Further negative capacities and negative inductances are considered which are independent of frequency. Next several a-c circuits are described having the property that the modulus of their impedances is independent of frequency. Hence a complicated "wave" form, such as speech, retains in such a circuit all its higher harmonics with their former amplitudes, though the phases of these harmonics are shifted. Oscillograms of vowels thus obviously show a very marked distortion, though the ear is unable to detect this phase distortion. The experiments confirm the well-known acoustical law of Ohm stating that within limits the ear is not able to detect phase shifts of the components of a complicated sound. View full abstract»

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  • The Accurate Testing of Audio Amplifiers in Production

    Page(s): 231 - 242a
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    The necessity for a means to obtain a quantitative check on radio receivers, as they are produced in considerable quantities, is becoming more and more apparent. This paper deals with a method for quickly comparing the voice frequency amplifying system of receivers, particularly those for use in broadcast reception, with a predetermined standard. The test is made on the two most important characteristics of the performance of an audio amplifier, namely the amplification within the band of audio frequencies, and the undistorted power output that it will deliver. View full abstract»

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  • A Study of Noise in Vacuum Tubes and Attached Circuits

    Page(s): 243 - 265
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    The noises originating in vacuum tubes and the attached circuits are investigated theoretically and experimentally under three headings: (1) shot effect with space charge, (2) thermal agitation of electricity in conductors, (3) noise from ions and secondary electrons produced within the tube. A theoretical explanation of the shot effect in the presence of space charge is given which agrees with experiment insofar as a direct determination is possible. It is shown that the tubes used should be capable of operating at full temperature saturation of the filament in order to reduce the shot effect. In the computation of the thermal noise originating on the plate side of a vacuum tube, the internal plate resistance of the tube is to be regarded as having the same temperature as the filament. Noise produced by ions within the tube increases as the grid is made more negative. With tubes properly designed to operate at temperature saturation it is possible to reduce the noise on the plate side to such an extent that the high impedance circuits employed on the grid side of the first tube of a high gain receiving system contribute practically all of the noise by virtue of the thermal agitation phenomenon. View full abstract»

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  • A Study of the Output Power Obtained from Vacuum Tubes of Different Types

    Page(s): 266 - 293
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    Economical operation of the large number of tubes involved in the Bell System makes necessary the adoption of common supply voltages. This requires that repeater tubes of various types be designed to operate at a fixed plate voltage. For this reason the design of amplifier tubes to give as large a power output as possible at the operating plate voltage is of considerable importance. In the case of three-electrode tubes it is possible from theoretical considerations to compute, approximately, the electrical parameters a tube must have in order to give the maximum output power of a given quality obtainable under fixed operating conditions. The electrical characteristics and output of fundamental, second, and third harmonics of two of the more common telephone repeater tubes are given. It is of considerable interest to determine whether greater power output of comparable quality can be obtained from tubes containing more than one grid. Since no sufficiently exact theoretical analysis of multi-grid tubes is yet available to permit the determination of the parameters of optimum tubes, a comparative experimental investigation of a number of such structures has been undertaken. The electrical characteristics and output of fundamental, second, and third harmonics of several such experimental tubes are given. The power output of multi-grid tubes and of three element tubes is compared. The reasons for the comparatively large power output of certain types of multi-grid tubes are discussed. View full abstract»

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  • The Equivalent Generator Theorem

    Page(s): 294 - 297
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    It is proved that any electrical network with two output terminals may be replaced by a generator and a series impedance without changing the current in an externally connected load. The voltage of the generator is the no-load voltage of the output terminals. The value of the series impedance is the impedance of the unloaded network looking into the output terminals. The use of the theorem is illustrated, and it is pointed out that it is valid for transient as well as steady state conditions. View full abstract»

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  • Filament Supply for Radio Receiver from Rectified 25-Kilocycle Current

    Page(s): 298 - 306
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    A method of generating, rectifying, and filtering 25-kc current for supplying filament power to ordinary d-c amplifier tubes in radio receivers is described. The oscillator used to generate the 25-kc current was of a special design and contained one or more UX-210 power tubes. The dry contact type rectifier unit was used, and cathode-ray oscillograms of the output current were taken. Operating tests were made of the performance of radio receivers. View full abstract»

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  • Quartz Control for Frequency Stabilization in Short-Wave Receivers

    Page(s): 307 - 320
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    For the purpose of stabilizing short-wave reception, experiments were made using quartz control in receivers. It was found that the use of a crystal which produces audible beats with the frequency of the transmitter quartz is practically impossible. In fact, the quartz-controlled oscillating detector caused too great a decrease in the tone volume, while in the case where a separate quartz-controlled heterodyne was used, the effect of temperature on the frequency of the crystals caused disturbances. In order to solve this problem, a method is described in which the superposition of the frequencies of the transmitter quartz and the receiver quartz produces an oscillation of high frequency. This intermediate frequency corresponds to a long wave and is made audible in a normal oscillating detector. View full abstract»

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  • A Broadcast Receiver for Use in Automobiles

    Page(s): 321 - 326
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    The purpose of this paper is to present several important features affecting the design of a broadcast receiver for use in automobiles. The design of the receiver is carried along step by step with special reference to (1) type of collector, (2) ignition shielding, (3) electrical characteristics of receiver, (4) physical structure of receiver, (5) power supply. From measurements made on an experimental receiver installed in an automobile the ignition interference is found to be greatest at the higher frequencies in the tuning range. Observations made during a road test of the receiver indicate a normal service range of from 50 to 100 miles on such stations as WJZ, WOR, and WEAF. The severe fluctuation of the signal encountered in travel through hilly country indicates the desirability of some form of automatic volume control. View full abstract»

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  • Some Remarks on the Multivibrator

    Page(s): 327 - 335
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    The author proposes to treat theoretically the production of oscillations by means of the multivibrator, and to formulate expressions for the period of these oscillations. View full abstract»

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  • Production Testing of Vacuum Tubes

    Page(s): 336 - 349
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    The factory testing of vacuum tubes is becoming more specialized every year. In the early days of broadcasting a few tubes served many purposes and actual performance in its relation to tube characteristics was not as widely studied and understood as it is today. Increasing knowledge of the how and why of tube and set operation has led to the development of many more or less special tubes designed for a specific function in the set. The increasing use of accurate set measuring equipment has enabled. designers to work out the optimum circuit arrangements for the use of these specially designed tubes in the various stages. As a result of this growth of the industry the testing of vacuum tubes has required more and more attention to set operation, a constant elaboration of test methods and equipment being necessary in order to exercise the necessary control over tube characteristics. View full abstract»

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  • Cross Modulation in R-F Amplifiers

    Page(s): 350 - 354
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    The causes of cross modulation in radio-frequency amplifiers are described, particularly in connection with the use of a non-selective input circuit, and in connection with the static characteristics of the screen-grid tube. Remedies for the difficulties are suggested. View full abstract»

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  • Book review

    Page(s): 355
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Aims & Scope

This Periodical ceased production in 1938. The current retitled publication is Proceedings of the IEEE.

Full Aims & Scope