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Radio Engineers, Proceedings of the Institute of

Issue 4 • Date April 1928

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Displaying Results 1 - 23 of 23
  • [Front cover]

    Page(s): c1 - c2
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  • Contents

    Page(s): 389
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  • General Information

    Page(s): 389
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  • Officers and Board of Direction, 1928

    Page(s): 390 - 392
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  • Laurens E. Whittemore [Biography]

    Page(s): 394 - 395
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  • Contributors to this issue

    Page(s): 396 - 397
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  • Institute activities

    Page(s): 398 - 407
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  • Modes of Vibration in Piezo-Electric Crystals

    Page(s): 416 - 423
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    The presence of nodes and antinodes on the surface of oscillating quartz crystals have been discovered. The symmetrical arrangement of these nodal points permits a study of the modes of vibration in the crystal plate and the use of the following formulas for determination of the velocity of sound waves through quartz and Young's modulus. V = F2T e= V2D. where V is the velocity, F the frequency, T the thickness of the plate, e Young's modulus and D the density. The value obtained for V was 5733 meters per second while 8.785X1011C. G. S. units represents Young's modulus for plane parallel to X-axis dimension. View full abstract»

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  • Some Characteristics and Applications of Four-Electrode Tubes

    Page(s): 424 - 446
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    Four-electrode tubes may be classified by their designs and uses as "screen-grid" tubes, "space-charge-grid" tubes, and "double function" tubes. In the screen-grid tube the inner grid is the control electrode and the outer or screen-grid is kept at a fixed potential. The capacity between plate and control-grid is thereby reduced to an almost negligible value. A second result of the screen-grid is a large increase in amplification factor and plate resistance without reduction of mutual conductance. This permits high amplification in connection with high impedance coupling circuits, without undesired regeneration or oscillation. The screen-grid principle has been applied to transmitting tubes as well as receiving tubes. Characteristics of these tubes are given in detail. In the space-charge-grid tube the outer grid is the control electrode and the inner grid is maintained at a fixed potential. The purpose of the inner grid is to reduce the effect of the space-charge around the filament and thereby reduce the plate resistance of the tube. The space-charge-grid tube performs the same functions as ordinary three-electrode tubes, but in general has higher mutual conductance than a three-electrode tube of similar design. Several double function tubes and circuits are described in which both grids act as control-electrodes or in which one grid acts as control electrode and the other as a combination space-charge-grid and control or output electrode. These circuits are sometimes useful but are subject to certain definite limitations. View full abstract»

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  • The Inverted Vacuum Tube, a Voltage-Reducing Power Amplifier

    Page(s): 447 - 461
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    By interchanging the functions of the grid and plate of the usual vacuum tube a voltage-reducing power amplifier is obtained. The usual vacuum tube acts as a voltage-increasing power amplifier. The static curves of the inverted vacuum tube are similar in form to the corresponding curves of the ordinary vacuum tube, and the theory of the inverted vacuum tube is analogous in all respects to the usual vacuum-tube theory, the only difference being reduction instead of amplification of voltage. It is relatively simple to construct an inverted vacuum tube with wide clearances between plate and the rest of the tube, so that potentials of hundreds of thousands of volts can be applied to the plate, while the effect of this high voltage stepped down in almost any desired ratio is obtained in a low-potential circuit. View full abstract»

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  • Development of a New Power Amplifier Tube

    Page(s): 462 - 474
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    A general rule for determining the best operating point and load impedance for any power amplifier when anode voltage and dissipation limits must both be considered is derived. The effect of varying the voltage factor in a given sized tube by changing the grid structure is also considered with voltage and heating kept within safe limits. The process of determining the desired characteristics for a given application is illustrated by describinq the development of a new power tube, Radiotron UX-250. View full abstract»

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  • Discussion

    Page(s): 474 - 475
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  • Measurement of Vacuum-Tube Capacities by a Transformer Balance

    Page(s): 476 - 481
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    A complete, portable equipment is described for the measurement of the direct capacities of vacuum tubes in laboratory or factory testing. The tube capacity is compared with a standard variable condenser by means of a transformer-balance (Neutrodyne) circuit, whose balance is independent of the frequency (about 1600 kc. being preferred). Designs are proposed for the standard condenser and the transformer, and suggestions are made for the further improvement of this equipment. View full abstract»

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  • A Direct-Capacity Bridge for Vacuum-Tube Measurements

    Page(s): 482 - 486
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    A direct-capacity bridge is described which permits the measurement at a single setting of a capacity associated with other capacities in a system having more than two terminals, such as the grid-plate capacity of a vacuutm tube. Two forms of the bridge are described. By making one connection the standard form of capacity bridge already in use in many laboratories may be converted into a direct-capacity bridge. The recommendation is made that vacuum-tube inter-element capacities be specified as direct capacities. Suggestions are made for other uses of the direct-capacity bridge in the laboratory. View full abstract»

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  • Discussion

    Page(s): 486
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  • A Bridge Method for the Measurement of Inter-Electrode Admittance in Vacuum Tubes

    Page(s): 487 - 493
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    A description is given of the Colpitts-Campbell bridge as applied specifically to the measurement of direct admittances in vacuum tubes. Data are given on several tubes. View full abstract»

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  • Broadcast Control Operation

    Page(s): 498 - 512
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    This paper is limited to a consideration of the audio-frequency elements of a broadcast control system. A two-studio electrically interlocked plant suitable for network operation is described. The methods of specifying and measuring telephonic energy levels, arranging low impedance (as 500-ohm) and bridging apparatus, equalizing lines, and maintaining the audio energy within permissible limits by means of amplifying and attenuating units are described in connection with the specifications of the plant. The co-ordinative and regulative functions of the technical staff of a broadcasting system, the relations of engineering and studio personnel and typical precautions against breaks in program continuity are then discussed. View full abstract»

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  • The Lorentz Reciprocity Theorem for Electric Waves

    Page(s): 513 - 518
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  • Book reviews

    Page(s): 519 - 520
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  • Bibliography on piezo-electricity

    Page(s): 521 - 535
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    In response to various requests, there is presented herewith a general bibliography on piezo-electricity and its applications. While the writer hopes that it is fairly complete to the beginning of 1928, still he realizes that some of the literature on the subject has doubtless been overlooked. He would be grateful to any who would call his attention to errors or omissions, since he hopes to publish a supplementary list at some future time. View full abstract»

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  • Geographical Location of Members Elected March 7, 1928

    Page(s): 536 - 537
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Aims & Scope

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

Full Aims & Scope