US1959165A - Electron discharge amplifier - Google Patents

Electron discharge amplifier Download PDF

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Publication number
US1959165A
US1959165A US63963032A US1959165A US 1959165 A US1959165 A US 1959165A US 63963032 A US63963032 A US 63963032A US 1959165 A US1959165 A US 1959165A
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United States
Prior art keywords
cathode
screen grid
amplifier
grid element
electron discharge
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Expired - Lifetime
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English (en)
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Priority to US63963032 priority Critical patent/US1959165A/en
Priority to FR762866D priority patent/FR762866A/fr
Priority to GB29743/33A priority patent/GB414927A/en
Priority to DEI48199D priority patent/DE635456C/de
Application granted granted Critical
Publication of US1959165A publication Critical patent/US1959165A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • 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
    • H03F1/08—Modifications of amplifiers to reduce detrimental influences of internal impedances of amplifying elements

Definitions

  • My invention has for one of its objects to provide an arrangement for preventing self-oscillation or reaction between the anode and grid circuits in an ultra high frequency amplifier by neu-- tralizing the eiiect of the inherent reactances of the cathode, the screen grid element and the leads connected thereto.
  • I provide means for maintaining the screen grid and the cathode at the radio frequency potentials under which condition maximum advantage is derived from the screening action of the screen grid.
  • a high frequency amplifier including an electron discharge device of the type commonly used in high and ultra high frequency transmitters. It is of course to be understood that my invention is also applicable to high and ultra high frequency amplifiers of low power such as are commonly used in radio receiving apparatus.
  • the electron discharge device 1 is provided with a filamentary cathode 2, a control grid 3, ascreen grid 4 and an anode 5.
  • the screen grid 4 is provided with the usual lead thereto extending throughone terminal of the electron discharge envelope adjacent to the leads connected to the filamentary cathode 2.
  • a second lead is connected to the screen grid at the other extremity thereof and this extends to a terminal 6 located at one side of the envelope.
  • This terminal is usually connected through a large capacitor (not shown) to the cathode and ground.
  • the amplifier is provided with a suitable input device or transformer 7, the secondary of which iscOnnected at one terminal to the control grid 3, and at the other terminal to a suitable source of grid biasing voltage which, in turn, is connected to the cathode and ground.
  • the output circuit of the amplifier is provided with a suitable output device or transformer 8, the primary of which is connected at one terminal tothe anode 5 and the other terminal of which is connected to the positive terminal of a suitable source'of anode voltage.
  • the filamentary cathode 2 may be energized by means of a transformer 9 which is connected to a suitable source of alternating current.
  • the screen grid 4 is supplied with positive voltage from a convenient source.
  • a plurality of capacitors 10 and 10a are connected in series across the connections to the cathode. The point between the capacitors is connected to the midpoint on the secondary of the transformer 9 and this is maintained at ground potential.
  • the amplifier as described is not suitable for amplification of frequencies above approximately 20 megacycles.
  • This amplifier depends upon its freedom from self-oscillation or anode circuit to grid circuit reaction upon the screen grid 4 which is interposedbetween the control grid 3 and the anode 5, and which is supposedly maintained at cathode potential for all frequencies. It has been found, however, that sufficient reactance exists along the length of the filament, the leads to the filament and the screen grid, and the screen grid itself, to permit the screen grid to assume potentials during high frequency operation which will depart from the cathode potential. This results in ineffective shielding and in unstable operation of the electron discharge device, thereby causing self-oscillations or giving rise to degenerative or regenerative coupling between the anode and control grid circuits. This is caused bythe grid circuit to plate circuit coupling which exists when the screen grid is not maintained at the same po tential as the cathode at the operating frequencies.
  • the screen grid lead-in adjacent to the conductors is main-' tained at alternating current ground and cathode potential by means of a'capacitor 11 which is connected to the ground and to the cathode.
  • a variable reactor 12 which may be either an inductor or a capacitor is connected between the ground and cathode, and the terminal 6 which is the connection to the other extremity of the screen grid 4.
  • the reactor 12 is adjusted so that its reactance value is equal and opposite to the algebraic sum of the reactances of the elements and leads at the operating frequency. This, however, does not imply that the series circuit comprising the cathode to screen grid capacity, leads and external capacitor 12 are all tuned to series resonance, as
  • Fig. 2 wherein I have diagrammatically shown the cathode 2, the screen grid element 4 and the capacitance A existing between these elements.
  • the reactance of the cathode structure itself is indicated by the rectangle B connected in series with the cathode and the reactance of the leads to the cathode which is indicated by the rectangle 0.
  • these reactances are inductive in nature, but they may be capacitive.
  • the reactance of the screen grid structure and the reactance of the screen grid leads are shown as rectangles D and E connected in series with the screen grid 4. These two systems are connected together by the capacitor 11.
  • a variable reactor 12 is inserted at any point in the loop circuit external to the discharge device, as for example a point between the capacitor 11 and the screen grid reactances D and E as shown in Fig. 3.
  • this reactor 12 serves to cancel the effect of the reactances existing in the circuit between the cathode 2 and the screen grid element 4 by way of circuit B, C, 11, D and E.
  • the reactor 12 is adjusted so that the algebraic sum of the reactances B, C, 11, 12, D and E is zero; thus no current will flow through the capacitance between the cathode and screen grid. Under this condition the screen grid is maintained at the same radio frequency potential as the cathode and the desired stable operation of the amplifier will be obtained.
  • This arrangement permits the amplifier to operate at ultra high frequencies and it is equally applicable to transmitting and receiving circuits.
  • a high frequency amplifier including an electron discharge device having a cathode, a screen grid element, and leads connected thereto, said screen grid element being provided with connections at either extremity, of means connected between one extremity of said screen grid element and said cathode for maintaining said extremity at radio frequency cathode potential, and means connected between said cathode and said other extremity of said screen grid element having reactance opposed to the inherent reactances of said cathode, said screen grid and the leads connected thereto, and of value sufficient to neutralize said inherent reactances.
  • a high and ultra high frequency amplifier including an electron discharge device having a cathode, a screen grid element, and leads connected thereto, said screen grid element being provided with connections at either extremity, of means connected between one extremity of said screen grid element and said cathode for maintaining said extremity at the same operating voltage as said cathode, and means connected between said cathode and said other extremity of said screen grid element for maintaining said screen grid at the same operating potential as the cathode at the operating frequency, said last means having a reactance opposite to, and sufiicient for neutralizing the algebraic sum of, the reactances of said cathode, said screen grid element and said leads connected thereto.
  • a high and ultra high frequency amplifier including an electron discharge device having a cathode, a screen grid element, and leads connected thereto, said screen grid element being provided with connections at either extremity, of a capacitor connected between one extremity of said screen grid element and said cathode, and a reactor connected between the other extremity of said screen grid element and said cathode, said reactor being arranged to provide at the operating frequency of said amplifier a reactance having a value sufficient to neutralize the algebraic sum of the reactances of said cathode, said screen grid element and said lead connected thereto whereby said screen grid element is maintained at the same radio frequency potential as the cathode at the operating frequency of the amplifier.
  • a high frequency amplifier including an electron discharge device having a screen grid element, a filamentary cathode, and leads connected thereto, said screen grid element being provided with leads at either extremity, of a by-pass capacitor connected between one extremity of said screen grid element and said cathode, and a variable reactor connected between the other extremity of said screen grid element and said cathode, said variable reactor being arranged to provide at the operating frequency of said amplifier a reactance having a value equal and opposite to the algebraic sum of the reactances of said cathode, screen grid element and said leads connected thereto whereby the maximum effect of said screen grid element is obtained.
  • a high frequency amplifier having an tion of an electron discharge amplifier having a cathode, a screen grid element, and leads connected thereto, which includes maintaining one end of said screen grid element at substantially radio frequency cathode potential, and maintaining the algebraic sums of the reactances of said leads, said cathode and screen grid elements at the operating frequency equal to zero.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Amplifiers (AREA)
  • Investigating Or Analyzing Materials By The Use Of Electric Means (AREA)
US63963032 1932-10-26 1932-10-26 Electron discharge amplifier Expired - Lifetime US1959165A (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
US63963032 US1959165A (en) 1932-10-26 1932-10-26 Electron discharge amplifier
FR762866D FR762866A (fr) 1932-10-26 1933-10-24 Perfectionnements aux montages avec tubes à décharge électronique
GB29743/33A GB414927A (en) 1932-10-26 1933-10-26 Improvements relating to electron discharge amplifiers
DEI48199D DE635456C (de) 1932-10-26 1933-10-27 Schaltung zur Verstaerkung kurzwelliger Schwingungen

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US63963032 US1959165A (en) 1932-10-26 1932-10-26 Electron discharge amplifier

Publications (1)

Publication Number Publication Date
US1959165A true US1959165A (en) 1934-05-15

Family

ID=24564910

Family Applications (1)

Application Number Title Priority Date Filing Date
US63963032 Expired - Lifetime US1959165A (en) 1932-10-26 1932-10-26 Electron discharge amplifier

Country Status (4)

Country Link
US (1) US1959165A (de)
DE (1) DE635456C (de)
FR (1) FR762866A (de)
GB (1) GB414927A (de)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE755332C (de) * 1937-09-03 1954-03-01 Telefunken Gmbh Einrichtung zum stoerungsfreien Betrieb von Roehren mit Bremsgitter in Kurzwellenschaltungen

Also Published As

Publication number Publication date
GB414927A (en) 1934-08-16
FR762866A (fr) 1934-04-19
DE635456C (de) 1936-09-17

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