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Radio Engineers, Proceedings of the Institute of

Issue 4 • Date April 1938

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Displaying Results 1 - 22 of 22
  • [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 March 2, 1938

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

    Page(s): vi - vii
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  • Officers and Board of Directors

    Page(s): viii
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  • Committees of the Institute of Radio Engineers 1938

    Page(s): ix - xi
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  • Institute news and radio notes

    Page(s): 387 - 399
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  • Correction

    Page(s): 400
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  • The Developmental Problems and Operating Characteristics of Two New Ultra-High-Frequency Triodes

    Page(s): 401 - 414
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    Large values of power are difficult to obtain in the ultra-high-frequency region. At the limiting frequencies it is increasingly more difficult to find vacuum tubes that will deliver such power and perform efficiently. The principal factors that affect the design and performance of the tubes are those involving the electrical circuit, the size requirements for the power desired, and the transit time of the electrons within the evacuated space of the tube. The design principles that result from a consideration of these factors have been used in the development of two new ultra-high-frequency triodes. A triode capable of delivering approximately 700 watts at 100 megacycles is described. This tube, which is cooled by water and air, is capable of operation as a neutralized power amplifier up to 200 megacycles with an output of approximately 500 watts. A second triode is described which is a radiation-cooled glass tube with a 300-watt plate-dissipation rating. Normal efficiency is obtained up to 40 megacycles and operation as a neutralized power amplifier is possible up to 100 megacycles. The efficiency at 100 megacycles is approximately 60 per cent. View full abstract»

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  • Constants of Fixed Antennas on Aircraft

    Page(s): 415 - 420
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    This paper presents the resistance and reactance characteristics of various fixed antennas on two types of modern aircraft, one a two-place low-wing metal military airplane of the attack type and the other a large mid-wing metal military airplane of the bombardment type, whose dimensions are comparable to those of modern commercial transport airplanes. A frequency range of from three to eight megacycles is covered in all cases and in some cases this range is extended. A description of the measuring equipment and method is included. View full abstract»

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  • Direct Measurement of the Loss Conductance of Condensers at High Frequencies

    Page(s): 421 - 432
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    A method of measuring the losses of a variable air condenser at high frequencies is described in which the condenser under test and the standard are connected in series as part of a tuned circuit. A radio-frequency voltage of resonant frequency is impressed on this circuit for a stated value of the standard. The unknown is then removed and the standard adjusted to resonance. The voltage across the tuned circuit is readjusted to its initial value by placing a conductance across the standard. The design of the standard condenser requires special considerations which are discussed. A self-biasing valve voltmeter, which is not critical to variations in power-supply voltage, is used. The results of measurements on several specimen condensers are given. A method of extending the measurements to higher frequencies is shown. View full abstract»

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  • The Variation in the High-Frequency Resistance and Permeability of Ferromagnetic Materials due to a Superimposed Magnetic Field

    Page(s): 433 - 441
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    The variation of the high-frequency resistance of ferromagnetic conductors as a function of a superimposed magnetic field is discussed. It is shown that very large changes in high-frequency resistance are obtainable in ferromagnetic conductors having high initial permeabilities. Some important applications of this effect are given. The application of high-frequency incremental permeability to remote tuning of radio circuits is briefly outlined. View full abstract»

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  • A Method of Neutralizing Hum and Feed-Back Caused by Variations in the Plate Supply

    Page(s): 442 - 448
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    A method is described whereby hum and feedback can be reduced in multistage screen-grid resistance-coupled amplifiers. By the method described it is possible to reduce degenerative and regenerative feedback and hum. The principle involves using the screen grid of a multigrid tube in such a manner that it produces a variation upon the grid of the followling tube substantially equal to and out of phase with the variation appearing at that grid directly through the plate-circuit resistor. The two thus neutralize out. The theory giving the conditions under which neutralization takes place is described. Experimental data prove that such neutralization does take place. Typical graphs giving the conditions for neutralization using a 6C6 tube are given. View full abstract»

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  • Harmonic Generation

    Page(s): 449 - 468
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    When plate current in a vacuum-tube amplifier flows for only a portion of the grid-excitation cycle, harmonics appear in the output circuit. The magnitude of any one of these harmonics depends upon the fraction of the fundamental cycle during which plate current flows. In the gradual transition from perfect class A to extreme class C operation, the magnitude of the nth harmonic goes through a series of n-1 maxima. To derive the maximum output for any given harmonic, the proper angle of plate-current flow must be chosen. In the present paper the case wherein the plate load is a large pure resistance to all frequencies is considered first. The results of this analysis are then carried over to the case of the tuned-plate-circuit load by the introduction of a simple function. Experimental verification of the analysis is made for harmonics up to and including the ninth. View full abstract»

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  • On Single and Coupled Tuned Circuits Having Constant Response-Band Characteristics

    Page(s): 469 - 474
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    The gain characteristic of a two-stage amplifier, one stage of which works into coupled tuned circuits while the other works into a single tuned circuit, is discussed. It is shown that this combination is capable of giving a flat response over a satisfactory band of frequencies and that the required circuit constants are easily computed. View full abstract»

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  • Armstrong's Frequency Modulator

    Page(s): 475 - 481
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    When the side bands of an amplitude-modulated signal are shifted 90 degrees and then recombined with the carrier, a frequency-modulated carrier results. In this paper the order and magnitudes of the distortion components of such a frequency-modulated carrier are quantitatively determined assuming an idealized receiver. It is found that this type of distortion will be negligibly small after frequency multiplication to obtain the desired carrier frequency. View full abstract»

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  • Characteristics of the Ionosphere at Washington, D.C., February, 1938

    Page(s): 482 - 485
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    Data on the ordinary-wave critical frequencies and virtual heights of the ionospheric layers are presented for the period indicated in the title. The monthly average values of the maximum usable frequencies for undisturbed days, for radio transmission by way of the regular layers is also provided. View full abstract»

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  • Contributors to this issue

    Page(s): 486 - 487
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  • Booklets, catalogs and pamphlets received

    Page(s): 488 - 490
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Aims & Scope

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

Full Aims & Scope