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Radio Engineers, Proceedings of the Institute of

Issue 7 • Date July 1933

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  • [Front cover]

    Page(s): c1
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  • Institute of Radio Engineers - Forthcoming Meetings

    Page(s): c2
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  • Contents

    Page(s): i
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  • General Information

    Page(s): ii
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  • Institute sections

    Page(s): iii
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  • Geographical Location of Members Elected June 7, 1933

    Page(s): iv
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  • Applications for Membership

    Page(s): v
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  • Officers and Board of Directors, 1933

    Page(s): vi
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  • E.R. Shute, Director, 1933

    Page(s): 886
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  • Institute news and radio notes

    Page(s): 887 - 908
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  • A Theory of Available Output and Optimum Operating Conditions for Triode Valves

    Page(s): 909 - 929
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    The output characteristics of triode and pentode valves have been investigated in the past by many workers, using either the static method of plotting a whole family of curves, or the dynamic method of measurement with a harmonic analyzer: these have not, however, led to many simplifying generalizations, and are cumbersome and difficult methods if they are to be applied to each individual valve. In this paper, the form of the triode curves is first investigated experimentally, and the allowable limits of dynamic swing thus determined for any given per cent harmonic: on this basis, a series of expressions are mathematically developed giving the required output characteristics in terms of an easily obtained valve constant (i.e., the valve alternating-current resistance at Va= 100, Vg= 0; this is the standard figure quoted by English manufacturers). Curves are given for output and correct plate current with various values of resistive load and of per cent harmonic limit, with or without conditions of limited anode dissipation. The case of the practical load with low direct-current resistance is examined, and the results are checked with a harmonic analyzer; the paper concludes with a few practical rules. It is hoped in a future paper to extend the analysis to cover push-pull circuits, the pentode valve, and the practical inductive load. View full abstract»

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  • Diode Detection Analysis

    Page(s): 930 - 943
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    This paper gives the current and output relations for the linear and square-law diode detector in terms of the detection efficiency and the detector and load resistances. The square-law case is shown to yield results similar to the linear for large input potentials and reasonable values of load. Employing the rectification-current-input-voltage characteristic, the graphical method is used to show that serious distortion is developed for deep modulation whenever an appreciable audio load is shunted across the diode resistor. It is found that M = 1 + D(A-1), where M is the modulation ratio at which cut-off begins, D the detection efficiency, and A the ratio of the audio impedance to the direct-current value of the diode load. The value of M is shown for various load conditions in both the linear and square-law cases. The paper shows that the use of a small condenser across the load decreases the detection efficiency but increases the input impedance. The connection to the driving circuit of a second diode for the development of automatic volume control potential is shown to cause distortion when such a tube is used with a delay bias. Mention is made of the importance of considering the impedance of the driving circuit, and attention is called to the failure of any of the methods of analysis to consider all of the factors involved. View full abstract»

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  • Application of Transformer Coupled Modulators

    Page(s): 944 - 957
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    A brief résumé of Heising's modulator theory is presented together with a discussion of the class B operation of tubes in a push-pull audio-frequency circuit. Several cases of commercial applications of class B audio amplifiers are mentioned. Several general problems involved in the use of a class B audio amplifier are discussed with the conclusion that such an amplifier will produce more audio power for a given tube complement, at higher efficiency, and with less distortion than amplifiers previously used in commercial applications. View full abstract»

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  • The Interdependence of Frequency Variation and Harmonic Content, and the Problem of Constant-Frequency Oscillators

    Page(s): 958 - 981
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    The investigations of the frequency variations in oscillating systems with negative nonlinear resistance were based until now on the fundamental differential equation of the simple oscillatory circuit. This method, although very exact, is not always sufficiently simple and even not always possible, especially if it concerns more complicated schemes. The symbolic calculus, although very simple in use, if applied to the nonlinear systems, gives only approximate results. The following paper represents the operation of nonlinear systems from a different point of view. Here the symbolic calculus has been used throughout in a complete and exact manner, by employing it for the fundamental frequency as well as for all harmonic frequencies which appear in the system. This could be done owing to the investigation of the negative resistance operation from the energy point of view. It was taken into consideration, that in the negative resistance characteristics i = f(v), i must be the univocal function of v, and therefore the area described by the instantaneous point of work during one cycle of the fundamental oscillation must be zero or, ⨖ idv = 0. On the other hand i and v can be considered, with regard to the external circuit connected to the negative resistance, as the sum of harmonic currents and voltages. In this way we obtain the formulas which allow the interdependence of the frequency variation and the content of harmonics to be determined. View full abstract»

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  • A Simplified Frequency Dividing Circuit

    Page(s): 982 - 983
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    A circuit is described in which a type 57, three-grid tube functions as two triodes in two separate oscillator circuits. One of the circuits is a crystal oscillator, and the other is a self-excited circuit which is controlled by the crystal so that it oscillates at a subharmonic of the crystal frequency. View full abstract»

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  • An Analysis of Power Detection

    Page(s): 984 - 989
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    The reasons for overloading of detectors as output devices is discussed. It is shown that in grid circuit rectification replacing the grid leak with a high impedance choke extends the overload point considerably. Using a 247 type pentode 800 milliwatts are obtained at the output circuit with seven per cent maximum distortion. View full abstract»

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  • Modes of Vibration of Piezo-Electric Crystals

    Page(s): 990 - 995
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    (a) A crystal is made to oscillate by subjecting it to the action of an air wave produced at a considerable distance from the crystal by a jet of air escaping from a small tube. The piezo-electric charge developed on the surface of the crystal as a result of the oscillation is mapped out by means of a tuned amplifier, and the vibration is analyzed into a fundamental and many overtones. For crystals that are long in one dimension, the overtones are nearly exact harmonics. (b) Exciting the crystal electrically by means of two tubes and especially designed electrodes, any harmonic up to the tenth can be produced. The crystal usually has only one mode of vibration for each pair of electrodes. View full abstract»

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  • A Method of Calculation of Field Strengths in High-Frequency Radio Transmission

    Page(s): 1003 - 1028
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    The theory on the transmission of high-frequency radio waves developed by one of the authors in a previous paper is applied to practical problems, and a systematic method of calculating the field strengths of high-frequency waves is established. The property of the ionization chart is explained and the method of construction of the chart is given. Practical examples of calculations are shown with respect to Tokio-Cape Town and Tokio-Melbourne circuits. The present method is most useful not only for the projection of a new high-frequency communication route, but also for the investigations of high-frequency transmission phenomena. From a number of measurements made on high-frequency transmission, it is shown that the coefficient of recombination in the F layer is about 1.5 × 10-10[sec-1] this value being in fairly good coincidence with the theoretical value. View full abstract»

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  • A Note on Nonlinearity in Transducers Used in Communication

    Page(s): 1029 - 1038
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    The characteristic of a nonlinear transducer can usually be expanded in a power series, when it is not simply a single term raised to some power. For those cases where the characteristic may be so expressed, a general law or equation is derived for the characteristic of a compensating transducer, that is, a transducer which in combination with the first transducer will produce over-all linearity. It is shown, moreover, that when the series for the distorting transducer is not sufficiently rapid in its convergence, it becomes impractical to realize the necessary compensating transducer. A simple case of an actual compensating transducer used to correct a square-law characteristic is briefly described. View full abstract»

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  • Tables for the Calculation of the Mutual Inductance of Any Two Coaxial Single-Layer Coils

    Page(s): 1039 - 1049
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    Absolute formulas for the calculation of the mutual inductance of coaxial solenoids, although they are required for work of the great precision necessary in absolute measurements, are not convenient for routine calculations. Series formulas, although simpler, are limited in the range of their convergence, thus requiring the choice of the proper formula for any given problem. The tables and formulas here presented enable the mutual conductance of any two coaxial solenoids whatever to be calculated from a single formula. Examples make clear that a five-figure accuracy may be attained with concentric coils and even with poorly coupled coils the error does not exceed a few parts in ten thousand. View full abstract»

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  • Some General Resonance Relations and a Discussion of Thevenin's Theorem

    Page(s): 1050 - 1054
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    It is shown that the maximum possible current which can be obtained through an impedance joining two points of a linear network is in general greater than the short-circuit current between those points; the maximum possible voltage is in general greater than the open-circuit voltage; the ratio of open-circuit voltage to short-circuit current is equal to the ratio of the maximum possible voltage to the maximum possible current, and both are equal to the magnitude of the input impedance of the network, etc. The condition for maximum voltage across a branch of a linear network is derived. As a preliminary, a form of Thevenin's theorem different from the usual one and of greater usefulness in the analytical solution of some circuit problems is obtained. View full abstract»

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  • Book reviews

    Page(s): 1055 - 1056
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  • Bookelts, catalogs, and pamphlets received

    Page(s): 1057
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  • Radio abstracts and references

    Page(s): 1058 - 1063
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Aims & Scope

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

Full Aims & Scope