US1883794A - Radio receiving apparatus - Google Patents

Radio receiving apparatus Download PDF

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Publication number
US1883794A
US1883794A US549164A US54916431A US1883794A US 1883794 A US1883794 A US 1883794A US 549164 A US549164 A US 549164A US 54916431 A US54916431 A US 54916431A US 1883794 A US1883794 A US 1883794A
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United States
Prior art keywords
circuit
frequency
circuits
inductance
radio
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US549164A
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English (en)
Inventor
Johnson John Kelly
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.)
BAE Systems Aerospace Inc
Original Assignee
Hazeltine Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority to NL36084D priority Critical patent/NL36084C/xx
Application filed by Hazeltine Corp filed Critical Hazeltine Corp
Priority to US549164A priority patent/US1883794A/en
Priority to GB12930/32A priority patent/GB384544A/en
Priority to DEH132376D priority patent/DE684956C/de
Priority to FR739762D priority patent/FR739762A/fr
Application granted granted Critical
Publication of US1883794A publication Critical patent/US1883794A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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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
    • H03D7/18—Modifications of frequency-changers for eliminating image frequencies

Definitions

  • radio frequency tuning circuits of a superheterodyne respond tothe comparative close inxage7 frequenc and ifk a second transmittingstation is within the range of the receiver and operates at, afrequency at or near the image frequency, the local oscillator frequency currents will combine therewith and the intermediate frequency stages will pass the beat frequency thus produced, resulting in a signal which may be characterized as an unpleasant combination of the desired and undesired signals.
  • lt is the object of the present invention to prevent the response of radio .receivers to undesired signals and particularly the production of undesired image frequency signals in a superheterodyne receiver.
  • an input transformer is provided, and
  • the secondary is tapped at a point such that the portion of said secondary above the tap
  • the by-pass circuit which includes the tuning element, is likewise tuned to the undesired or image frequency.
  • the misalignment between the actual image frequency and by-pass frequency is made as slight as possible and may be made zero for any point of the range desired.
  • the voltage variations vbetween the tap and the ground end'of the secondary are used to supply a voltage to a second tuned circuit, which circuit is vutilized to impress the signals upon the radio frequency amplifying devices, detectors, etc.
  • FIG. 1 shows the imput radio frequency circuits o'f a radio receiver embodying this invention
  • Fig. 2 shows the tuned radio frequency circuits, embodying this invention, used in con- ⁇ *will be at node potential relative tocurrents nection with the input of a radio receiver as, for instance, a superheterodyne; 1
  • Fig. 3 is an elementary circuit diagram illustratingy the principles of the present 1n- 5 vention.
  • Figs. 4, 5, 6 and 7 are elementary diagrams of modified circuits for carrying out the principles of the invention.
  • Fig. 1 shows the tuned input of a radio relo DC.
  • the antenna A is connected to the ground G through the primary P of the transformer T1.
  • the secondary S of the transformer is tapped at point 14, said tap being connected to the primary P2 of the transformer T2.
  • 1n shunt with the secondary S is the tuning condenser C1, said secondary S and condenser C1 forming a tuned circuit 10 resonant to the frequency of the desired signals.
  • Circuit 10 is made resonant to the desired frequency either by variation -of the condenser C1,made variable-as shown, or by variation of the inductance of the secondary S.
  • the secondary S2 of the transformer T2 is shunted by condenser C2, forming the tuned circuit 12 which is tuned to the desired. frequency in a manner similar to that inwhich circuit 10 is tuned.
  • Circuit 12 is connected to the input of thermionic device 13 which may be the radio frequency amplifier or detector of a radio receiver, as desired.
  • FIG. 2 This circuit is particularly adapted for'use in a superheterodyne radio receiver. It differs from Fig. 1, just described, principally by the use of a volumecontrol variable resister R, a variable portion of lwhich is shunted across the primary P of the transformer T1.
  • the cathode of the thermionic device 13 is also variably connected to ground thro gh the resistor R for the purpose of varying t e amplification of said device by varying its grid bias potential.
  • Transformer '1 1 includes also a second primary P1 which may be wound on the secondary for the purpose of increasing the gain of said trans- I ormer by increasing the capacity coupling i between the primary and secondary.
  • This circuit is in other particulars essentially the same as that shown in Fig. 1.
  • the secondary S comprises 125 turns and the tap is vtaken 51 turns from the ground end.
  • the condensers C1 vandCz may be connected together for uni-control operation.
  • the circuit of Fig. 3 is the same as the circuit shown in Fig. 1 except that the inductances are differently arranged for the purpose of explaining the action of the circuit used in accomplishing the objects of this invention.
  • the secondary S of transformer T1 is ta ped at point 14.
  • the two portions Sfand S9' that, relative to the points 14 and 15, S and C1 will constitute a-"by-pass to currents of an undesired frequency.
  • the voltage gain characteristic curve of the portion S will show zero voltage at the image frequency, whereas the natural resonance of the circuit 10 may be such that a considerable voltage will be developed at a frequency the same amount on the other side of the signal frequency, thus producing a non-symmetrical curve relative to the voltages between points 14 and 15 at the different frequencies.
  • the points 14 and 15 are connected to the primary P2 of the transformer T2, thus forming a link circuit 11.
  • the primary P2 does not have impressed across it all of the voltage variations which are available across the secondary winding S, but only those existing across the substantially reduced portion S.
  • the primary P2 is inductively related to the secondtuned circuit are so proportioned
  • the tap point 14 12 through the secondary S2 the resonance characteristics of which permit the amplification to be made the maximum obtainable in the second of two coupled tuned circuits.
  • substantially optimum coupling will be obtained regardless of the loss occasioned by the tapping of the secondary.
  • Fig. 4 shows a coupling circuit in which the link circuit 11 includes a condenser C3.
  • the o circuit 11 may be made resonant to a frequency below the band it is desired to receive, in order to increase the response of thewhole coupling circuit at low frequencies.
  • the inductance of P2 must be l5 ⁇ made relativel high, and the coupling between P2 and g2 must be relatively loose.
  • Fig. 5 is a second modification of the circuit constituting the present invention.
  • the link circuit 11" includes a portion S2 of the inductance S2 in addition to the series condenser C3.
  • a circuit of this type gives a bettery response at high frequencies in which the current flowing in the linl circuit is greater.
  • it is imff portant in this circuit that the capacity of C2 be small to prevent short-circuiting of the portion S of secondary S.
  • Fig. 6 shows a third modification of the circuits embodying the invention.
  • the primary P2 of the transformer T2 is closely coupled to the high-potential end of the resonant circuit 12.
  • the winding P2 may be in such a direction relative to the winding of the secondary S2 that th inherent capacity coupling C.2 between the primary P2 and secondary S2 will either oppose orl aid the mutual inductivecoupling between said primary and secondary.
  • the capacitive, coupling C4 is in opposition to the inductive coupling, the response of the circuits is reduced at the higher frequencies.
  • Fig. 7 is still another modification of the circuits embodying this invention.
  • the tap 14 is so chosen that the image frequency response of the tuning circuits will be reduced. However, when a tuned radio frequency receiver is used the tap may be so taken that any objectionable signal may be rejected. I claim: i fr 1.
  • Signal selecting circuits for a radio receiver comprising a circuit :tunable to the frequency of the current it is desired to receive, a second circuit tunable to the same frequency, and a link circuit connecting portions of the impedances of each of said circuits, tlie portion of the impedance of the first of said circuits being shunted by a circuit resonant to the currentof a frequency it is not desired to receive and said link circuit being nade resonant to current of a frequency lower than the band of frequencies to which v said circuits are tunable.
  • a signal selecting device for a superheterodyne radio receiver which comprises a circuit ltunable to a current of the frequency it isV desired to receive, a second circuit likewise tunable to the current of the frequency it is desired to receive, and a link circuit connecting a portion of the impedance of said first mentioned circuit and inductively related to the second mentioned circuit, the portion of the impedance of said first mentioned circuit being so chosen that its terminals remain at substantially n ode potential relative to the image frequency of said receiver as the circuits are tuned, said circuits being so proportioned that the gain of said second circuit will compensate to some extent for the loss occasioned by the tapping of only a portion of the desired signal voltage across the first mentioned circuit.
  • a tuned radio frequency selective device for a radio receiver including a circuit tunable to the frequency -of a current to be received, asecond circuit also tunable to the frequency of the current to be received. and a link circuit connecting portions of the impedances of each of said circuits, the portion of the impedance of the first of said circuits being so selected that its terminals are at node potential relative to currents of an undesired frequency, and said link circuit having a resonance at a frequency outside the band of frequencies to be-,covered by said circuits whereby to emphasize the response to frequencies toward one side of the band.
  • Signal selecting circuits for a radio re- Y DC which comprise al first circuit includsired to receive, a link circuit connected between said circuits including a portion of the inductance of the first of said circuits and at least a portion of the impedance of said second-mentioned circuit, said link circuit being proportioned so that the impedance shunting4 the selected portion of said inductance remains substantially resonant to current of a particular undesired frequency as the circuits are tuned, said link circuit being resonant to a frequency below the band of frequencies to which it is desired to tune the said circuits whereby the gain of said circuits is increased at low frequencies.
  • a signal selecting device for a super' heterodyne radio receiver which comprises a circuit tunable to a current of the frequency it is desired to receive, including aninductance and a capacity, a second circuit likewise tunable to the frequency ⁇ of the current it is desired to receive, also including an inductance and a capacity, a link circuit connected toV a portion of the inductance of the said first mentioned circuit and inductively related to said second mentioned circuit, a portion of the inductance of said first mentioned circuit being so chosen that its terminals are at node potential relative to the image frequency of said receiver, and a capacity of said link circuit so selected that said link circuit is resonant to a frequency outside the band of frequencies tol Which it is desired to tune said receiver.
  • a signal selecting device for a radio frequency receiver which comprises a circuit tunable to a current of the frequency it is desired to receive including an inductance and a capacity, a second circuit likewise tunable to the frequency of the current it is desired to receive also including an inductance and a capacity, and a link circuit connecting a portion of the inductance of said first mentioned circuit and including an inductance which is inductively related to the inductance of said second mentioned circuit, the portion of the inductance of said first mentioned circuitV being so chosen that its terminals are at node potential relative to a specific frequency which it is not desired to receive.
  • a radio signal selecting circuit for a frequency as the circuits are tuned said link circuit includin an inductance inductively related to the high potential Vend of the inductive reactance of said second tuned circuit whereby the coupling between said tuned circuits includes the mutual inductance between the inductance of said link circuit and the inductive reactance of said second circuit and the inherent capacity between said inductances.
  • a signal-selecting device for a radio receiver which comprises a circuit tunable to a current ofthe frequency it is desired to receive, including an inductance and a capacity, a second circuit likewise tunable to the frequency of the current it is desired to receive also including an inductance and a capacity, and a link circuit connected to a portion of the inductance of ⁇ said first mentioned circuit and including an inductance of relatively high impedancewhich is inductively related to the inductance of said second mentioned circuit, the portion of the inductance lof said first mentioned circuit being so chosenthat its terminals are at node potential relative to a specific frequency which it is not desired to receive, said circuits being so proportioned that substantially optimum coupling will be had between said first and said second mentioned circuits.
  • a signal selecting device for asuperheterodyne radio receiver which comprises a circuit tunable to a current of the frequency it is desired to receive, including inductive and capacitive reactances, a second circuit likewise tunable to the frequency it is desired to receive also including inductive and capacitive reactances, and a link circuit connected toa portion of the reactances of said first mentioned circuit and including a relatively high inductance inductively related yto the inductive reactance of the second mentioned circuit, the portion of the reactance of said first mentioned circuit being so chosen that its terminals are at node potential to the image frequency of said receiver, said circuits being so proportioned that the gain of said second mentioned ycircuit will permit optimum coupling regardless of the loss occasioned by tapping off only a portion of the desired signal voltage available in said rst mentioned circuit.
  • a signal selecting device for a radio receiver which comprises a circuit tunable to a current of the frequency it is desired to receive including an inductance and a capacity, a second circuit likewise tunable to the frequency of the i current it is desired to receive, and also including an inductance and a capacity, a link circuit connecting a portion of theinductance of said first mentioned circuit and including an inductance which is inductively related to the inductance of said second mentioned circuit, the portion of the d inductance of said first mentioned circuit be ing so chosen that its terminals are at node potential relative to a specific frequency which it is not desired to receive, and a capacity in ⁇ said link .circuit so selected'that -said link circuit is resonant to a frequency below the band of frequences to which it is desired to tune said receiver.
  • Radio signal selective circuits for superheterodynel radio receivers which com-v prise two radio frequency circuits tunable to the frequency of the current it is desired to receive, each including inductive and capacitive reactances, a link circuit connected across a port/ionof the reactance of one of said tuned'circuits so selected that the terminals of said link circuit'are at node potential relative to a current of the image frequency and including an inductance inductively related to the high potential end of the inductive reactance .of the second of said tuned circuits whereby the coupling between said tuned circuits includes the mutual inductance between the inductance of Said link circuit and the inductive reactance of said second mentioned circuit and the inherent capacity between said inductances, the winding of said inductances being so arranged that the mutual inductance coupling will oppose the capacitiveY coupling between the link circuit and the second of said circuits, thus providing a lesser response at the high frequency portion of the tuning range of said circuits.
  • a radio signal selecting device for a radio receiver which comprises two radio frequency circuits tunable to the frequency of the current to be received by said receiver, each including an inductance and a capacity, a link circuit connected across a portion of the inductance of the first of said tunedL circuits so selected that the terminals of said link circuit are at node potential relative to the current of an undesired frequency, said link circuit including an inductance inductively related to the high potential end of the inductance ofY said second tuned circuit whereby the coupling between said tuned circuits includes the mutual inductance between the inductance of said link circuit and the inductance of said second mentioned circuit and the inherent capacity between said inductances.
  • a radio signal selective device fr radio receivers which comprises two radio frequency circuits tunable to the frequency of the current it is desired tok receive, each including an inductance and a capacity, a link circuit connected across a portion of the inductance of one of said tuned circuits so se.
  • the terminals of said link circuit are at node potential relativeto current of an Vundesired frequency and including an inductance inductively related to the high potential end of the inductance of the second of said tuned circuits
  • the'coupling between said tuned circuits includes the mutual inductance between the inductance of said link v,circuit and the 'inductance of said second mentioned circuit and the inherent capacity between said inductances, the winding ofsaid inductances being so arranged that the mutual inductance coupling will oppose the capacitive couplingbetween the link circuit and the second of said circuits, thus providing a lesser response at the high frequency portion of the tuning range of said circuits.
  • a radio frequency tuning system for a radio receiver of the superheterodyne type which comprises two circuits tunable to the frequency of the current itis desired to receive, each circuit comprising inductive and capacitive'reactances, and a link circuit connected' to lsaid tuned circuits, including a portion of the inductance of each of said circuits, that portion of the inductance ofthe first of said circuits beingpso selected that the terminals of said link circuit will remain at substantally node potential relative to a current of the image frequency of said receiver as the circuits are tuned, and said link circuit including an open end winding inductively and capacitively related to the inductance of the second of said circuits whereby said link circuit comprises the capacitive coupling between said open end winding a-nd the inductance of said second circuit and a portion of the inductance's of each ofsaid tuned circuits.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Superheterodyne Receivers (AREA)
  • Input Circuits Of Receivers And Coupling Of Receivers And Audio Equipment (AREA)
  • Channel Selection Circuits, Automatic Tuning Circuits (AREA)
US549164A 1931-07-07 1931-07-07 Radio receiving apparatus Expired - Lifetime US1883794A (en)

Priority Applications (5)

Application Number Priority Date Filing Date Title
NL36084D NL36084C (fr) 1931-07-07
US549164A US1883794A (en) 1931-07-07 1931-07-07 Radio receiving apparatus
GB12930/32A GB384544A (en) 1931-07-07 1932-05-05 Radio receiving apparatus
DEH132376D DE684956C (de) 1931-07-07 1932-07-05 Abstimmbares Kopplungsglied fuer die Eingangskreise von Mischroehren von UEberlagerungsempfaengern
FR739762D FR739762A (fr) 1931-07-07 1932-07-07 Perfectionnements aux appareils d'accord à haute fréquence

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US549164A US1883794A (en) 1931-07-07 1931-07-07 Radio receiving apparatus

Publications (1)

Publication Number Publication Date
US1883794A true US1883794A (en) 1932-10-18

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Family Applications (1)

Application Number Title Priority Date Filing Date
US549164A Expired - Lifetime US1883794A (en) 1931-07-07 1931-07-07 Radio receiving apparatus

Country Status (5)

Country Link
US (1) US1883794A (fr)
DE (1) DE684956C (fr)
FR (1) FR739762A (fr)
GB (1) GB384544A (fr)
NL (1) NL36084C (fr)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE940236C (de) * 1953-06-27 1956-03-15 Telefunken Gmbh Roehrenschaltung mit Rueckkopplungsspule zwischen Anode und Kathode, insbesondere Mischsufe
US4601062A (en) * 1985-02-28 1986-07-15 Rca Corporation Tracking image frequency trap

Also Published As

Publication number Publication date
DE684956C (de) 1939-12-09
FR739762A (fr) 1933-01-17
GB384544A (en) 1932-12-08
NL36084C (fr)

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