US2488948A - Repeatered transmission system, including multifilament amplifiers - Google Patents

Repeatered transmission system, including multifilament amplifiers Download PDF

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Publication number
US2488948A
US2488948A US788380A US78838047A US2488948A US 2488948 A US2488948 A US 2488948A US 788380 A US788380 A US 788380A US 78838047 A US78838047 A US 78838047A US 2488948 A US2488948 A US 2488948A
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Prior art keywords
cathode
current
resistance
voltage
parallel
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Expired - Lifetime
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US788380A
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English (en)
Inventor
Edmund A Veazie
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AT&T Corp
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Bell Telephone Laboratories Inc
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Priority to NL67449D priority Critical patent/NL67449C/xx
Priority to NL696909930A priority patent/NL142201B/xx
Application filed by Bell Telephone Laboratories Inc filed Critical Bell Telephone Laboratories Inc
Priority to US788380A priority patent/US2488948A/en
Priority to FR968922D priority patent/FR968922A/fr
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J1/00—Details of electrodes, of magnetic control means, of screens, or of the mounting or spacing thereof, common to two or more basic types of discharge tubes or lamps
    • H01J1/02—Main electrodes
    • H01J1/13—Solid thermionic cathodes
    • H01J1/135—Circuit arrangements therefor, e.g. for temperature control
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F1/00—Details of amplifiers with only discharge tubes, only semiconductor devices or only unspecified devices as amplifying elements
    • H03F1/52—Circuit arrangements for protecting such amplifiers
    • H03F1/54—Circuit arrangements for protecting such amplifiers with tubes only
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F1/00—Details of amplifiers with only discharge tubes, only semiconductor devices or only unspecified devices as amplifying elements
    • H03F1/52—Circuit arrangements for protecting such amplifiers
    • H03F1/54—Circuit arrangements for protecting such amplifiers with tubes only
    • H03F1/544—Protection of filaments
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B17/00—Monitoring; Testing
    • H04B17/40—Monitoring; Testing of relay systems
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B3/00—Line transmission systems
    • H04B3/02—Details
    • H04B3/44—Arrangements for feeding power to a repeater along the transmission line
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04M—TELEPHONIC COMMUNICATION
    • H04M3/00—Automatic or semi-automatic exchanges
    • H04M3/40—Applications of speech amplifiers

Definitions

  • This relates in general to electrical transmission systems. More particularly, it relates to an improvement in repeaters in a repeatered submarine cable system.
  • a more specific object of the present invention is to provide a vacuum tube suitable for use in repeater amplier stages which is designed to give a longer period of satisfactory uninterrupted service than those of the prior art.
  • the present invention relates to an extended submarine cable system including a plurality of repeaters wherein the amplifier tubes are energized by individual heater circuits connected together in series, and each comprising a pair of parallel-connected twin filaments in a single cathode sleeve shunted by an auxiliary resistor of critical design.
  • modified forms of the invention are described which are adaptable for use in conjunction with diiferent types of systems, such as those in which constant volt- 2 age is supplied to the vacuum tube heater circuit terminals.
  • cathode heating element will be understood to refer to a pair of heater filaments connected in parallel in a single cathode sleeve in accordance with the teachings of this invention.
  • cathode heater circuit or heater circuit will refer to the cathode heating element as defined in the foregoing; paragraph in circuit relation with a critically valued auxiliary resistor, which may be connected thereto in series or in shunt in accordance with the teachings of the present invention.
  • FIGs. 1A and 1B are diagrams illustrating the theory of the invention, as hereinafter described;
  • Figs. 2A and' 2B show modifications in the arrangement within the cathode sleeve of a conventional vacuum tube in accordance with the present invention
  • Figs. 3 and 4 are graphical representations of experimental data, which illustrate the theory of the present invention.
  • Fig. 5 shows a schematic arrangement of circuit elements in accordance with the present invention in a system having a substantially constant current supply
  • Fig. 6 shows a modified arrangement of elements in accordance with the present invention -ina system wherein the voltage supplied to the terminals of the cathode heater circuit is substantially constant;
  • Fig. 7 shows a preferred form of the present invention comprising a repeatered submarine cable system in which the amplifier tubes are 'energized by constant-power cathode heating ⁇ vacuum tube cathode heating element comprising two similar laments is mounted within a single cathode sleeve with the laments connected in parallel either inside the tube or externally.
  • constant current is supplied to; such a cathode heating element in combination with a suitably chosen external resistance, the power dissipated within the cathode sleeve will remain constant even lthough one of the iilaments breaks and ceases to l6 0 draw power.
  • Equation 2 If now R2 breaks or is disconnected it has been shown by Equation 2 that E should bo 14.1 volts if W1 is to be 20 watts.v At E equal to 14.1 volts:
  • R1 and R2 are non-linear resistance elements.
  • Io represent the total current through this ⁇ pair of resistors
  • Eo represent the voltage across them for one state in which the total power is at the desired level, as indicated in Fig. 1B of the drawing.
  • I0 and En' be the values of Voltage and current for the same power for another condition of these resistances.
  • the total current I through R1, R2 and R3 for the first condition will then be:
  • Equation l5 a more specific expression for R3 may be derived as follows:
  • Ei I0 is simply the resistance of a single heater iilament operated at 'the desired power level and is the resistance of the parallel heater filaments operated at the same power level.
  • Equation 24 shows that R3 should be the geometric mean of the resistances for the two conditions at which the power is to be the same. This holds even though the heater laments do not have linear resistances.
  • an extruded cylindrical insulating element l having a crosssectional dimension of the order of a small fraction of an inch, is designed to be supported in a central position in a tube of the type referred to in the foregoing paragraph.
  • the insulating ele- ⁇ ment I is surrounded by the cathode 2 which comprises a nickel sleeve 2a on which has been sprayed a cathode coating 2b comprising the usual electron emitting material.
  • the insulating element I is provided with four internal bores of the order of one-hundredth of an inch in diameter, which are parallel with the longitudinal axis thereof, and which are arranged symmetrically thereabout, so that a substantial spacing is provided between each bore and the bores adjacent thereto.
  • the bores are labeled A, B, C and D.
  • the helically wound U-shaped laments 3 and 4 are coated with a thin layer of ceramic, and are of such dimensions relative to the diameters of the bores A-D, that they may be readily inserted therein.
  • the laments 3 and 4 are respectively arranged to occupy adjacent bores, although they may be cross-connected if properly insulated at the point of cross-over.
  • the ends of the filaments 3 and 4 are brought out below the insulator I and connected in parallel to the terminals 5 and 6.
  • the teachings of the present invention can be applied in each of the specic modifications described in detail hereinafter by connecting the heating element terminals 5 and 6 to a suitable source of current and connecting the proper critically valued auxiliary resistor in series or in shunt therewith, as the case demands.
  • a twin-element tube such as shown in Figs. 2A and 2B which will be described hereinafter will be better understood by reference to the curves of Fig. 3.
  • These curves representing the current in the heating element as the function of the applied voltage are based on the operation of an experimental tube equipped with twin laments, such as indicated in Fig. 2B, in which one end of each filament is brought out through a separate tap, whereby the two filaments are readily connected either in parallel or with a single filament in the circuit, and the other disconnected.
  • Curve A which shows the voltage-current relationship for the twin laments connected in parallel
  • curve B which shows that for a single one of the laments, are plotted in coordinate axes of which the Y axis represents current in amperes, and the X axis represents voltage in volts.
  • a hyperbola C showing the locus or all points for which the power EI equals some chosen constant value, in this case 5.0 watts.
  • the intersections of the hyperbola C with the characteristic curves A and B give the operating points at which the cathode power is equal to 5.0 watts. If a line be drawn through these points extending through the vertical current axis, the point of intersection gives directly the total current I which must be supplied to the tube shunted by the re sistor.
  • the correct value for the shunting resistor R3 in accordance with the present invention is given by the negative reciprocal of the slope of this line.
  • tungsten temperature has been found to be only moderately higher when only one of the twin heater laments is operating than when both are operating.
  • inherent defects in the wire more often cause failure of heater filaments than burn-out because of excessive operational temperatures. Rupture of one lament of a pair thus does not seriously reduce the life of the other.
  • a space discharge device T of the type described, with reference to Figs. 2A and 2B hereinbefore, has a cathode heating element comprising twin heater filaments 3 and 4 connected in parallel within the sleeve of the electron-emitting cathode 2.
  • the heating element comprising filaments 3 and 4 is connected in series with a substantially constant source of current 1, which may be construed as any electrical system having a resistance of such relative magnitude that rupture of one of the laments 3 or 4 causes a substantially inappreciable change in the total current through the system.
  • a silicon carbide varistor 8 Connected across the heating element terminals in parallel with the twin filaments 3 and 4 is a silicon carbide varistor 8 of the type described in the article by Grisdale, supra, and designed in accordance with the teachings of this invention to maintain the dissipation of power into the cathode 2 substantially constant, irrespective of the rupture of one of the iilaments 3 or 4.
  • the potential saving in power which might be achieved using a circuit such as shown in Fig. 5 is shown by the broken line curve D of Fig. 3, which represents a possible current-voltage characteristic of the varistor 8.
  • the curve D indicates a reduction of 50 per cent in the current wastage in the circuit of Fig. 4, over that required in a circuit, such as shown in Fig. 1, in which Re is linear.
  • ballast lamp such as is disclosed in an article entitled The ballast resistor in practice by H. A. Jones, General Electric Review, volume XXVIII, No. 5, May 1925.
  • the design theory of such devices is discussed further by the same author in an article entitled The theory and design of ballast resisters in the September 1925 issue of the same periodical.
  • a resistor of this type for use with a cathode heating element having the characteristics illustrated in Fig. 3 should pass a current of 0.300 ampere at some voltage in the :dat section of its characteristic, and at a voltage 7.7 volts lower should pass a eurent of 0.205 ampere.
  • Fig. 4 illustrates the way in which this ballast lamp would function.
  • Curves A, B and C here are the same as in Fig. 3.
  • Curve F shows the calculated ballast lamp current as a function of the supply voltage minus the ballast lamp voltage. It is apparent that 4for a supply Voltage of approximately 26 volts the desired conditions are met. The saving in supply voltage in this case in comparison with that for use of a linear series resistor is thus of the order of l5 volts.
  • an electron discharge device T such as described hereinbeiore with reference to Figs. 2A and 2B, has a cathode 2 energized by twin parallel-connected heater laments 3 and 4, which are connected in series with a ballast lamp 9 of the type described, and a source of substantially constant potential, such as the storage battery l0.
  • This circuit functions in the manner described hereinbefore to maintain the power dissipated within the cathode 2 substantially constant, irrespective of the rupture of one of the twin iilaments 3 or 4.
  • the regulation 0I the power source should be such that a change in the current load from Io to Io causes a change in the voltage across the cathode heating element from Eo to En. If the regulation is too good, as in the constant voltage case, it must be made poorer by use of a series resistor. If the regulation is poor, as in the constant current case, it must be improved by use of a shunt resistor. In any case, the resistance between the terminals of the cathode heating element looking back from that element should be adjusted to have the value Two yfurther itemsof interest may be developed from a study of the curves of Fig. 3.
  • the total power including loss in Re with both filaments functioning is EOI Aand amounts, for example, in the actual case shown, to 8.45 watts.
  • the useful power actually supplied to the cathode was watts, the indicated efciency thus being about 59 per cent.
  • the indicated voltage rise when one filament opens would be Eo'-E0 or 7.8 volts, or about 47 per cent of the normal voltage across the heating element. If several tubes in series are being considered, the voltage rise brought about -by a single open filament wouldynot be excessive from a practical standpoint.
  • twin heater filaments referred to in the foregoing discussion might be of any conventional type. While some forms might afford less wastage of power than others, and therefore, be more desirable, any Atype can theoretically be used. Moreover, from the theory set forth hereinbefore it is ⁇ apparent that three or more heater laments of equal resistance might be used in parallel with any of the circuit arrangements of the present invention, the value of the resistor R3 being correspondingly modified.
  • a preferred embodiment of the present invention which is shown in Fig. 7 -of the -drawings contemplates the use of a multiplicity of heater circuits designed in accordance with the principles hereinbefore set forth, which are connected in series ⁇ to energize the cathodes in the repeater amplifier stages in an extended undersea cable system for the transmission of speech and telegraph signals, such as disclosed in the patent vto O'. E. Buckley cited hereinbefore.
  • comprises a'plurality of sections, each having an inner ⁇ conductor 422 and a grounded outer vconductor 23, which are connected in se ries through a plurality of repeater stations cornprising the amplifier stages 24 which may be assumed for the purposes of illustration to be substantially similar in circuit detail, with the exception of the heater circuits 25, to the disclosure of Fig. 2 of Patent 2,342,544 to O. B. Jacobs, February 22, 1944.
  • the heater circuits may assume any of the forms described hereinbefore which are adapted to operate with a substantially constant supply of current, such as those in Fig. 1A, 1B and 5, and including an arrangement of heater elements such as described with reference to Figs. 2A and 2B.
  • the heater filaments 3 and :i which are ineluded in the heater circuits 25 have substantially equal values and are connected in parallel within the sleeve of the cathode 2, in a manner described in detail hereinbefore.
  • the parallel combination of heater filaments 3 and d is shunted by the critically valued resistance eleinent R.
  • the voltage-current characteristic of the element R in accordance with theory set forth hereinbeiore, should have a slope ap,- proxirnating the geometric mean of the resistance vaiues of the heater filaments 3 and ai in parallel operating at the desired power level and that ci' one of the filaments alone operating at the same power level. If the element R is nonlinear, it may assume forms such as described in detail with reference to Fig. 5 hereinbefore.
  • the heater circuits 25 are connected in series with respective sections of the inner cable conductor 22 through the khigh frequency choke coils and 2i.
  • En" ergizing .current ⁇ of the order of 9.5 ampere for the heater circuits 25 is derived from the negative direct current source 28 at the western cable terminal and from the positive direct current source 29 at the eastern cable terminal.
  • Speech and/or telegraph signals are transmitted over the submarine cable system 2i in the usual manner, utilizing conventional signaling circuitse ,and 3.5 which are respectively located at the western and eastern cable terminals, and which are coupled to the central cable conductor 22 at said respective terminals through the transformer circuits 36 and 32'.
  • input and output trans- Y formers V33 andi provide similar coupling for the transmission of speech and telegraph signals between Vthe amplifier stages in the said repeater circuits and successive sections of the central cable conductor 22.
  • An electrical transmission system including repeaters, one of said repeaters including a space discharge device having a cathode, anda separate energizing circuit for said cathode, said ein cuit comprising a pair of cathode-heating filaments of substantiallyequal resistance connected in parallel, means for maintaining the total power dissipated in saidiaments at a substantially constant -value irrespective of the rupture of one of the laments of said pair, said means comprising an auxiliary resistance element con nected in shunt with said pair of filaments.
  • auxiliary resistance has a value which approximates the geometric mean of the resistance of the iilaments of said pair connected in parallel and the resistance of one of said filaments connected singly.
  • An electrical transmission system having repeater circuits comprising space discharge devices having separately energized cathodes, energizing circuit for each of said space discharge devices, said energizing circuits connected in series to a source of power, certain of said energizing circuits comprising a pair of substantially equal cathode-heating resistances connected in parallel, and an auxiliary resistance connected in shunt with the resistance of said pair.
  • a system in accordance with claim 4 having substantially constant current, irrespective of the rupture of one of the cathode-heating resistances of said pair.
  • auxiliary resistance has a value which approximates the geometric mean of the cathodeheating resistances of said pair connected in parallel and one of said cathode-heating resistances connected singly.
  • a system comprising in combination a substantially constant source of current, a space discharge device including a separately energized cathode, an energizing circuit for said cathode connected in circuit relation with said source, said energizing circuit comprising a pair of substantially equal cathode-heating resistances connected in parallel, and means comprising an auxiliary resistance connected in shunt with the cathodeheating resistances of said pair to maintain the power dissipated by said energizing circuit at a substantially constant value, irrespective of the rupture of one of the cathode-heating resistances of said pair.
  • auxiliary resistance comprises a varistor having a voltage-current characteristic such that the current increase is greater than in direct proportion to the applied voltage.
  • a system comprising in combination a substantially constant source of voltage, a space discharge device including an indirectly heated cathode, a cathode energizing circuit for said cathode in circuit relation with said source, said energizing circuit comprising a pair of substantially equal heating resistances connected in parallel, and an auxiliary resistance connected in series with said energizing circuit, said auxiliary resistance having a value which approximates the geometric mean of the heating resistances of said pair connected in parallel and one of said heating resistances connected singly.
  • auxiliary resistance comprises a device having a voltage current characteristic such that the current increase is less than in direct proportion to the applied voltage.
  • a system comprising in combination a source of power, a space discharge device including a cathode energizing circuit in circuit relation with said source, said energizing circuit comprising a pair of substantially equal heating resistances connected in parallel, and means connected in circuit relation with said energizing circuit to maintain the power dissipation in said energizing circuit substantially constant, said means comprising an auxiliary resistance having a value which approximates the geometric mean of the heating resistances of said pair connected in parallel and one of said heating resistances connected singly.
  • a submarine cable system comprising in combination a plurality of cable sections interconnected With repeaters, said repeaters comprising signal-repeating tubes having indirectly heated cathodes energized by individual heater circuits, all of said heater circuits connected in series with each other through said cable sections, a source connected to supply energizing current to said heater circuits over said cable sections,certain of said heater circuits comprising a cathode heating element which comprises a plurality of resistances connected in parallel in a single cathode sleeve, and an auxiliary resistance connected in parallel with said heating element, the said cable system having so great a resistance that the current supplied by said source remains substantially constant irrespective of the rupture of one of the resistances of said element, and said auxiliary resistance having such a value that the power dissipated in said heating element remains substantially constant irrespective of the rupture of one of the resistances of said element.
  • said heating element comprises a pair of substantially equal heating resistances connected in parallel
  • said auxiliary resistance has a value which approximates the geometric mean of the heating resistances of said pair connected in parallel and one of said heating resistances oonnected singly.

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  • Engineering & Computer Science (AREA)
  • Signal Processing (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Power Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Amplifiers (AREA)
US788380A 1947-11-28 1947-11-28 Repeatered transmission system, including multifilament amplifiers Expired - Lifetime US2488948A (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
NL67449D NL67449C (is") 1947-11-28
NL696909930A NL142201B (nl) 1947-11-28 Werkwijze voor het kleuren van een anodisch geoxydeerd aluminium werkstuk, alsmede aldus gekleurd, anodisch geoxydeerd werkstuk.
US788380A US2488948A (en) 1947-11-28 1947-11-28 Repeatered transmission system, including multifilament amplifiers
FR968922D FR968922A (fr) 1947-11-28 1948-07-08 Système de transmission à répéteurs

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US788380A US2488948A (en) 1947-11-28 1947-11-28 Repeatered transmission system, including multifilament amplifiers

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US2488948A true US2488948A (en) 1949-11-22

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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2843803A (en) * 1956-03-29 1958-07-15 Rca Corp Vacuum tube input circuit
US2936385A (en) * 1958-04-25 1960-05-10 Western Electric Co Heater insulator for indirectly heated cathode
US3105125A (en) * 1959-10-30 1963-09-24 Bell Telephone Labor Inc Power separation filter
US3119931A (en) * 1960-06-28 1964-01-28 Philips Corp Circuit means for coupling an x-ray device to a control supply apparatus
US3214627A (en) * 1961-02-24 1965-10-26 Tokyo Shibaura Electric Co Rapid-start cathode-ray tubes

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB190812398A (en) * 1908-06-09 1909-06-03 William Dierman Improvements in or relating to Installations of Electric Lamps having Metal Filaments
US1654513A (en) * 1919-09-03 1927-12-27 Rca Corp Electron-emission device
US1699011A (en) * 1925-12-07 1929-01-15 Murphy Edmund Guyer Vacuum tube
US1833968A (en) * 1925-11-19 1931-12-01 American Telephone & Telegraph Amplifying system
US1862393A (en) * 1927-11-10 1932-06-07 Radio Patents Corp Thermionic amplifying circuits
US1940181A (en) * 1928-09-18 1933-12-19 American Telephone & Telegraph Vacuum tube circuits
US2020875A (en) * 1931-12-31 1935-11-12 Bell Telephone Labor Inc Energization and control of amplifiers
US2020318A (en) * 1934-03-06 1935-11-12 Bell Telephone Labor Inc System including repeater

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB190812398A (en) * 1908-06-09 1909-06-03 William Dierman Improvements in or relating to Installations of Electric Lamps having Metal Filaments
US1654513A (en) * 1919-09-03 1927-12-27 Rca Corp Electron-emission device
US1833968A (en) * 1925-11-19 1931-12-01 American Telephone & Telegraph Amplifying system
US1699011A (en) * 1925-12-07 1929-01-15 Murphy Edmund Guyer Vacuum tube
US1862393A (en) * 1927-11-10 1932-06-07 Radio Patents Corp Thermionic amplifying circuits
US1940181A (en) * 1928-09-18 1933-12-19 American Telephone & Telegraph Vacuum tube circuits
US2020875A (en) * 1931-12-31 1935-11-12 Bell Telephone Labor Inc Energization and control of amplifiers
US2020318A (en) * 1934-03-06 1935-11-12 Bell Telephone Labor Inc System including repeater

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2843803A (en) * 1956-03-29 1958-07-15 Rca Corp Vacuum tube input circuit
US2936385A (en) * 1958-04-25 1960-05-10 Western Electric Co Heater insulator for indirectly heated cathode
US3105125A (en) * 1959-10-30 1963-09-24 Bell Telephone Labor Inc Power separation filter
US3119931A (en) * 1960-06-28 1964-01-28 Philips Corp Circuit means for coupling an x-ray device to a control supply apparatus
US3214627A (en) * 1961-02-24 1965-10-26 Tokyo Shibaura Electric Co Rapid-start cathode-ray tubes

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Publication number Publication date
NL142201B (nl)
FR968922A (fr) 1950-12-08
NL67449C (is") 1900-01-01

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