US2131194A - Superheterodyne receiver - Google Patents

Superheterodyne receiver Download PDF

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Publication number
US2131194A
US2131194A US67343A US6734336A US2131194A US 2131194 A US2131194 A US 2131194A US 67343 A US67343 A US 67343A US 6734336 A US6734336 A US 6734336A US 2131194 A US2131194 A US 2131194A
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United States
Prior art keywords
grid
tube
circuit
oscillation
neutralizing
Prior art date
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Expired - Lifetime
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US67343A
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English (en)
Inventor
Schlesinger Kurt
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Loewe Opta GmbH
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Loewe Opta GmbH
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Publication date
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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03D—DEMODULATION OR TRANSFERENCE OF MODULATION FROM ONE CARRIER TO ANOTHER
    • H03D7/00—Transference of modulation from one carrier to another, e.g. frequency-changing
    • H03D7/06—Transference of modulation from one carrier to another, e.g. frequency-changing by means of discharge tubes having more than two electrodes
    • H03D7/10—Transference of modulation from one carrier to another, e.g. frequency-changing by means of discharge tubes having more than two electrodes the signals to be mixed being applied between different pairs of electrodes
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B15/00—Suppression or limitation of noise or interference
    • H04B15/02—Reducing interference from electric apparatus by means located at or near the interfering apparatus
    • H04B15/04—Reducing interference from electric apparatus by means located at or near the interfering apparatus the interference being caused by substantially sinusoidal oscillations, e.g. in a receiver or in a tape-recorder
    • H04B15/06—Reducing interference from electric apparatus by means located at or near the interfering apparatus the interference being caused by substantially sinusoidal oscillations, e.g. in a receiver or in a tape-recorder by local oscillators of receivers

Definitions

  • the present invention relates to receivers employing locally generated oscillations and its main object is to prevent radiation of local oscillations, especially when the local oscillator operates on a short or ultra-short wave.
  • a radio receiver employing locally generated oscillations for beating with oscillations collected by the antenna, radiation of the locally generated oscillations from the antenna is prevented by means of a neutralizing circuit.
  • Fig. 1 shows diagrammatically the frequency changing circuit of a superheterodyne receiver
  • Fig. 2 is a more constructional embodiment employing a circuit similar to that of Fig. 1, and
  • Figs. 3 and 4 are modifications of the circuit of Fig. 1.
  • Fig. 1 shows the frequency changing circuit of a superheterodyne receiver comprising a mixing valve 4 and an oscillatory valve 8; these two valves may be combined in a single envelope.
  • the antenna I is connected through a very small condenser 2 of about 1 cm. to the control grid 3 of the mixing valve 4 whose cathode 5 is earthed.
  • a screen grid 5 serves to screen the control grid 3 from the oscillation grid 1.
  • Two or more screen grids may be provided.
  • a screen grid 32 may be arranged between anode 3
  • the triode 8 whose cathode 9 is likewise earthed, produces the local oscillations in conjunction with a circuit comprising condenser l and inductance ll.
  • the circuit is so chosen that, in addition to the oscillation potential applied to electrode 1 of the mixing hexode 4, there is always present a small oscillation potential which is opposite in phase to that of the former.
  • the disturbing radiation produced by superheterodyne receivers is primarily due. to the capacity between the control grid 3 and the oscillation grid 1. Owing to the presence of the screen grid 6, this capacity amounts in practice to only about 0.1 cm. In spite of this small value a disturbing radiation, which increases with increase in size of the antenna I, takes place when the, local oscillations are of very high frequency, e. g. in the case of ultra-shortwaves of 7 m. length the capacitive reactance of this condenser amounts only to 35,000 ohms.
  • This radiation may be reduced by employing two screen grids 6 and 6 instead of one. This should, however, be regarded only as an approximation to complete freedom from radiation.
  • the supply conductor 3' should be completely screened in the interior of valve 4 'againstinternal coupling capacities by means of a shield l6.
  • a completeelimination of radiation without employing a second screen'grid t" is effected by applying a neutralizing oscillation to the antenna I.
  • An adjustable fraction of p the oscillations produced by local'oscillator 8 and which is at reverse phase to that at grid I2, is taken through a very small adjustable condenser l8 and supplied to the control grid terminal l9.
  • the very small neutralization capacity I8 is advantageously produced by a screened coupling condenser.
  • An earthed plate I801; is inserted between the coupling plates of l8. y
  • the oscillator circuit valve 8' and oscillating circuit I0, ll may be compared with a capacitatively coupled three-point-circuit (the German term is: Dreiticiansclien) which represents a capacitative potentiometer circuit by which incase of short waves the reverse phase of auxiliary potential is best attained'
  • the inherentearth capacities l3 and M of the oscillat ing circuit I0, I l are authoritative for the anodecathode potential and the grid-cathode potential of valve 8; and these operating potentials are opposed in phase. generally quite small (order of magnitude 10 cm.) the circuit can oscillate only at'highoper ating frequencies; in case. of very high frequencies the required phase opposition is attainedmost Since capacities l3 and M are accurately.
  • the state of reverse phase between anode and grid of the oscillatory system is also improved byconnecting the-anode supply consis of the frequency changing stage of the receiver is made of metal and indicated by 20.
  • the chassis is closed on all sides and earthed.
  • One plate of condenser I8 is connected tothe oscillation circuit I0, I I which is located in the interior of the oscillator box 20.
  • the other plate of condenser I8 is connected to the antenna I (either directly as shown in Fig. 2, or via condenser 2 as shown in Fig. 1. In the latter case the value of the coupling capacity I8 is greater).
  • supplies grid bias to the control grid 3 through a very short conductor 22, and is also connected to coupling condenser 2 and thus the antenna I.
  • the intermediate plate I8a of condenser I8 partly covers the aperture 35 in the portion of the chassis separating the plates of condenser I8 and its position is adjusted by the screw 23.
  • the neutralizing oscillations pass through conductor 24 to antenna I.
  • the antenna I radiates on account of the harmful capacity between. the oscillation grid I and the control grid 3 already mentioned.
  • the coupling via condenser I8 is increased until a point is found at which the radiation from the antenna is neutralized.
  • the process of neutralizing by means of a reverse phase auxiliary potential derived from the oscillator is not limited to the circuits of Figs. 1 and 2.
  • the reverse phase potential may be produced, as shown in Fig. 3, by means of an auxiliary winding 26 which is inductively coupled to the oscillator coil II.
  • the auxiliary oscillations obtained in this way will be exactly at reverse phase to those applied to grid 3 via the inter-electrode capacity 29 so long as the resonant frequency of winding 26 is higher than the oscillation frequency of circuit I 0, II.
  • the tuning system which is connected to the control grid 3 may be otherwise than as shown in Figs. 1 and 2. For example, as shown in Fig.
  • an oscillation circuit 27, 28 may be employed for antenna tuning without disturbing the neutral ization because the neutralization is free from phase displacement. Also the coupling of antenna I to grid 3 may be made inductive without disturbing the action of the neutralizing process. Finally the neutralizing oscillations may also be introduced into the tuning circuit 27, 28 by means of an inductive coupling.
  • the invention is especially suitable for use in radio receivers operating on ultra-short waves which may be modulated e. g. with speech currents or television signals.
  • a mixing tube having a cathode, a control grid, at least one screen grid, an oscillation grid, a second screen grid and an anode, arranged in the order named, an aerial circuit coupled with said control grid, an oscillatory tube having an anode, a cathode,
  • a neutralizing circuit for compensating the undesired coupling between the controland oscillation-grid of said mixing tube efiected by the inherent capacity between said two grids, said neutralizing circuit consisting of a variable condenser connected between the control grid of said mixing tube and the grid of said oscillator tube so that a neutralizing potential of opposite phase with respect to the original oscillatory potential is led from an electrode of said oscillatory tube to the control grid of said mixing tube and the aerial circuit respectively the anode of said oscillator tube being coupled to the oscillation grid of said mixing tube.
  • a mixing tube having a cathode, a control grid, at least one screen grid, an oscillation grid, a second screen grid and an anode, arranged in the order named, an aerial circuit coupled with said control grid, an oscillatory tube having an anode, a cathode, and a grid, a neutralizing circuit for compensating the undesired coupling between the controland oscillation-grid of said mixing tube effected by the inherent capacity between said two grids, a variable neutralizing condenser connected in the coupling circuit between the control grid of said mixing valve and the anode or grid of said oscillator tube, so that a neutralizing potential of opposite phase with respect to the original oscillatory potential is led from the anode of said oscillatory tube to the control grid of said mixingtube and the aerial circuit respectively the control grid of said oscillatory tube being coupled to the
  • a mixing tube having a cathode, a control grid, at least one screen grid, an oscillation grid, a second screen grid and an anode, arranged in the order named, an aerial circuit coupled with said control grid, an oscillatory tube having an anode, a cathode, and a grid, a neutralizing circuit for compensating the undesired coupling between the controland oscillation-grid of said mixing tube effected by the inherent capacity between said two grids, said neutralizing circuit consisting of a variable condenser connected between the control grid of said mixing tube and the anode of said oscillator tube so that a neutralizing potential of opposite phase with respect to the original oscillatory potential is led from an electrode of said oscillatory tube to the control grid of said mixing tube and the aerial circuit respectively, the control grid of said oscillatory tube being coupled to the oscillator grid
  • a mixing tube having a cathode, a control grid, at least one screen grid, an oscillation grid, a second screen grid and an anode arranged in the order named, an aerial circuit coupled with said control grid, an oscillatory tube having an anode, a cathode, and a grid, a neutralizing circuit for compensating the undesired coupling between the controland oscillation-grid of said mixing tube effected by the inherent capacitybetween said two grids, said neutralizing circuit consisting of a variable condenser connected between the control grid of said mixing tube and the grid of said oscillator tube, so that a neutralizing potentialof opposite phase with respect to the original oscillatory potential is led from an electrode of saidoscillatory tube to the control grid of said mixing tube and the aerial circuit respectively, the anode of said oscillator tube being coupled to -the oscil
  • a mixing tube having a cathode, a control grid, at least one screen grid, an oscillation grid, a second screen grid and an anode arranged in the order named, an aerial circuit coupled with said control grid, an oscillatory tube having an anode, a cathode, and a grid, a neutralizing circuit for compensating the undesired coupling between the controland oscillation-grid of said mixing tube effected by the inherent capacity between said two grids,
  • variable neutralizing condenser connected between the control grid of said mixing valve and the anode of said oscillator tube, so that a neutralizing potential of opposite phase with respect to the original oscillatory potential is led from an electrode of said oscillatory tube to the control grid of said mixing tube and the aerial circuit respectively, said oscillator tube and also said mixing tube with their appertaining coupling element being surrounded by an earthed screening means, which is closed on all sides and within which all part-capacities are rendered invariable and out of which there are passed only the aerial lead and the feed lines, said feed lines are pro-,
  • a mixing electrode system having a cathode, a control grid, at least one screen grid, an oscillation grid, a, second screen grid and an anode, arranged in the order named, an aerial circuit coupled with said control grid, an oscillatory electrode system having an anode, a cathode, and a grid, a neutralizing circuit for compensating the undesired coupling between the controland oscillation grid of said mixing electrode system effected by the inherent capacity between said two grids, a variable neutralizing condenser connected in the coupling circuit between the control grid of said mixing electrode system and the anode of said oscillator electrode system, so that a neutralizing potential of opposite phase with respect to the original oscillatory potential is led from an electrode of said oscillatory electrode system to the control grid of said mixing electrode systemand the aerial circuit respectively, the control grid of said oscillatory tube being
  • a heterodyne receiver for the use in short wave art and ultra-short wave'art, means for preventing radiation of the locally generated oscillation by the receiver aerial, a mixing tube having a cathode, a control grid, at least one screen grid, an oscillation grid, a second screen grid and an anode, arranged in the order named,
  • an aerial circuit coupled with said'control grid, an oscillatory tube having an anode, a cathode, and a grid, a neutralizing circuit for compensating the undesired coupling between the controland oscillation-grid of said mixing tube effected by the inherent capacity between said two grids,
  • variable neutralizing condenser connected in r the coupling circuit between the control-grid of said mixing tube and the grid of said oscillator tube, so that a neutralizing potential of opposite phase with respect to the original oscillatory potential is led from'the anode of said oscillatory tube to the control grid of said mixing tube and the aerial circuit respectively, the anode of said oscillatory tube being coupled to the oscillation grid of said mixing tube, said neutralizing condenser being constructed as a screened condenser having a metal sheet which may be inserted be tween its two electrodes in more or less large extension.
  • a mixing tube having a cathode, a control grid, at least one screen grid, an oscillation grid, a second screen grid and an anode, arranged in the order named,
  • an oscillatory tube having an anode, a cathode, and a grid
  • a neutralizing circuit for compensating the undesired coupling between the controland oscillation-grid of said mixing tube effected by the inherent capacity between said two grids
  • said neutralizing circuit consisting of a variable condenser connected between the control grid of said mixing tube and the anode of said oscillator tube so that a neutralizing potential of opposite phase with respect to the original oscillatory potential is led from an electrode of said oscillatory tubetothe control grid of said mixing tube and the aerial circuit respectively, the control grid of said oscillatory tube being coupled to the oscillation grid of said mixing tube,
  • said neutralizing condenser being constructed as a screened condenser having a metal sheet which may be inserted between its two electrodes in more or less large extension, said oscillator tube and also said mixing tube with their appertaining circuit elements being surrounded by an earthed screening means, which is closed on all sides and within which all part-capacities are rendered invariable and out of which there is passed only the aerial lead.
  • a heterodyne receiver for the use in short wave art and ultra-short wave art, means for preventing radiation of the locally generated oscil lation by-the receiver aerial, a mixing tube having a cathode, a control grid, at least one screen grid, an oscillation grid, a'second grid and an anode, arranged in the order named, an aerial circuit coupled with said control grid, an oscillatory tube having an anode, a cathode, and'a grid,
  • a neutralizing circuit for compensating the uning tube and the grid of said oscillator tube so that a neutralizing potential of opposite phase with respect to the original oscillatory potential is led from an electrode of said oscillatory tube to the control grid of said mixing tube and the aerial circuit respectively, the anode of said oscillator tube being coupled to the oscillation grid of said mixing tube, said oscillator electrode systern and the electrode of the mixing electrode systern are arranged in the same tube.
  • a heterodyne receiver for the use in short wave art and ultra-short wave art, means for preventing radiation of the locally generated oscillation by the receiver aerial, a mixing tube having a cathode, a control grid, at least onescreen grid, an oscillation grid, a second screen grid and an anode arranged in the order named, an aerial circuit coupled with said control grid, an oscillatory tube having an anode, a cathode, and a grid, a neutralizing circuit for compensating the undesired coupling between the controland oscillation-grid of said mixing tube effected by the inherent capacity between said two grids, said neutralizing circuit consisting of a variable condenser connected between the control grid of said mixing tube and the grid of said oscillator tube so that a neutralizing potential of opposite phase with respect to the original oscillatory potential is led from an electrode of said oscillatory tube to the control grid of said mixing tube and the aerial circuit respectively, the anode of said oscillator tube being coupled to the oscillation grid of said mixing

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Superheterodyne Receivers (AREA)
  • Oscillators With Electromechanical Resonators (AREA)
  • Variable-Direction Aerials And Aerial Arrays (AREA)
US67343A 1935-03-12 1936-03-05 Superheterodyne receiver Expired - Lifetime US2131194A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE458147X 1935-03-12
DE2147556X 1935-04-06

Publications (1)

Publication Number Publication Date
US2131194A true US2131194A (en) 1938-09-27

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US67343A Expired - Lifetime US2131194A (en) 1935-03-12 1936-03-05 Superheterodyne receiver
US72314A Expired - Lifetime US2147556A (en) 1935-03-12 1936-04-02 Superheterodyne receiver

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Application Number Title Priority Date Filing Date
US72314A Expired - Lifetime US2147556A (en) 1935-03-12 1936-04-02 Superheterodyne receiver

Country Status (5)

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US (2) US2131194A (en, 2012)
BE (2) BE414283A (en, 2012)
FR (2) FR803289A (en, 2012)
GB (2) GB458147A (en, 2012)
NL (1) NL46582C (en, 2012)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1014605B (de) * 1955-08-19 1957-08-29 Hazeltine Corp Schaltung zur Verhinderung der UEberfuehrung einer Schwingung innerhalb eines vorbestimmten Frequenzbereichs vom Ausgangskreis eines Verstaerkers in seinen Eingangskreis

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NL127041C (en, 2012) * 1959-08-08

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1014605B (de) * 1955-08-19 1957-08-29 Hazeltine Corp Schaltung zur Verhinderung der UEberfuehrung einer Schwingung innerhalb eines vorbestimmten Frequenzbereichs vom Ausgangskreis eines Verstaerkers in seinen Eingangskreis

Also Published As

Publication number Publication date
BE414854A (en, 2012)
FR803289A (fr) 1936-09-26
GB458147A (en) 1936-12-14
US2147556A (en) 1939-02-14
GB458149A (en) 1936-12-14
BE414283A (en, 2012) 1936-04-30
FR47248E (fr) 1937-02-20
NL46582C (en, 2012) 1939-09-15

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