US2097937A - High frequency oscillating circuit - Google Patents

High frequency oscillating circuit Download PDF

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Publication number
US2097937A
US2097937A US44045A US4404535A US2097937A US 2097937 A US2097937 A US 2097937A US 44045 A US44045 A US 44045A US 4404535 A US4404535 A US 4404535A US 2097937 A US2097937 A US 2097937A
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Prior art keywords
frequency
circuit
grid
resistance
valve
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Expired - Lifetime
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US44045A
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English (en)
Inventor
Rust Noel Meyer
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RCA Corp
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RCA Corp
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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03J—TUNING RESONANT CIRCUITS; SELECTING RESONANT CIRCUITS
    • H03J7/00—Automatic frequency control; Automatic scanning over a band of frequencies
    • H03J7/02—Automatic frequency control
    • H03J7/04—Automatic frequency control where the frequency control is accomplished by varying the electrical characteristics of a non-mechanically adjustable element or where the nature of the frequency controlling element is not significant
    • H03J7/042—Automatic frequency control where the frequency control is accomplished by varying the electrical characteristics of a non-mechanically adjustable element or where the nature of the frequency controlling element is not significant with reactance tube
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03B—GENERATION OF OSCILLATIONS, DIRECTLY OR BY FREQUENCY-CHANGING, BY CIRCUITS EMPLOYING ACTIVE ELEMENTS WHICH OPERATE IN A NON-SWITCHING MANNER; GENERATION OF NOISE BY SUCH CIRCUITS
    • H03B5/00—Generation of oscillations using amplifier with regenerative feedback from output to input
    • H03B5/08—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element comprising lumped inductance and capacitance
    • H03B5/10—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element comprising lumped inductance and capacitance active element in amplifier being vacuum tube
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
    • H04B1/06—Receivers
    • H04B1/16—Circuits
    • H04B1/30—Circuits for homodyne or synchrodyne receivers

Definitions

  • This invention relates to electrical high frequency oscillating circuit arrangements and has for its object to provide improved means whereby the tuning or natural frequency of a. high 5 frequency electrical oscillating circuit may be automatically varied in dependence upon departures from predetermined desired results in such manner as to correct for such departures,
  • the invention is. based upon the fact that .by' virtue of so-called Miller effect the space between the electrodes of an electron. discharge device may be arranged to present a substantially pure reactance of a magnitude which can be varied by 25 varying the operating constants of the device,,
  • a reactance so presented is utilized as a variable reactance in' a high frequency tuned circuit to be automatically controlled; the operating constants of said de- 30 vice being varied in dependence upon departures from results desired to be obtained, such varia-' tions being such as to produce variations in tuning in a sense to compensate for the departures.
  • FIG. 1 shows a homodyne circuit embodying the invention
  • FIG. 2 shows a portion of a superheterodyne receiver embodying the invention inan oscillator fre-. 4.0 quency control circuit
  • Fig. 3 illustrates a modification of Fig. 2.
  • the local 45 oscillator of the said receiver in the particular embodiment illustrated includes certain of fthe electrodes of a so-called heptode valve l, i. 'e; a valve having a cathode 2, an anode 3 and five grids 4, 5, 6, I, 8, in succession between cathode 50 and anode.
  • valve grids will, for the sake of brevity,be dew scribed in reference to their order as-counted, from the cathode; for example, the first'grid'is the grid 4 nearest the cathode, the second grid 55 is the next'grid 5 and so on.
  • the first grid 4 is connected to thecathode 2 through a leak resistance 9 and is'also connected through a coupling condenser l and a parallel tuned circuit consisting of an inductance l I shunted by a variable condenser l2 to the negative terminal l3 of the anode potential source (not shown).
  • the second grid 5 is connected through a coil 14 which is adjustably coupled to the coil II to a source of positive potential (not shown) connectedjat [5, the cathode 2 and the first and second grids 4 and 5 accordingly constituting the electrode system of a local oscillator which is utilized as the local oscillator of a homodyne receiver,
  • a third coil I6 coupled to the coil i I is utilized to take off local oscillatory energy 15' to the homodyne detector (not shown).
  • the third and fifth grids 6, 8, are connected together and to a suitable source of positive potential connected at I1.
  • the fourth grid 1 is coupled through a coupling condenser l8 to a point (not shown) of the receiver from which received high frequency signal voltage (for locking purposes) is obtainable, the said grid 7 being also connected through a resistance l9 to a variable tapping point upona potentiometer resistance 2
  • the said cathode is connected through a milliammeter 23in-series with a choke 24 and a second potentiometer resistance 25 to the terminal l3.
  • the potentiometer resistance 25 is shunted by a condenser 26 and a second condenser 21 is shunted across the series connected choke 24 and resistance 25'the said choke and two condensers constituting a low pass filter across which is effectively shunted the resistance 25.
  • An adjustable tapping point 28 upon the resistance 25 is connected through a further resistance 29 to the control grid'30 of a valve 3
  • a pentode valve is utilized as the variable reactance device and the, control grid 30 is connected to the anode 33 thereof through a variable condenser 32 which servesto increase the anode-grid capacity .of the valve and which-can be varied to adjust the value of the apparent input reactance of the valve 3
  • the 'second grid 34 of the valve 3! receives positive bias from any convenient source (as shown it is connected to terminal I!) and the cathode"35 of the valve 3
  • the anode 33 of the valve 3! is connected through frequency expected to be present and desired to.
  • the low pass filter will pass on to the second potentiometer 25, 23 (from which potential for the control grid of the valve 3! is" obtained) either slow beats due to the interaction, between the local oscillations and locking signal oscillations or--if the' 'local oscillator is operating accurately at signal frequency-a resultant direct current depending for its magnitude upon the relative phase between the local oscillations and the locking signal oscillations.
  • the plate circuit of the he-ptode may be used for anypurpose.for example it may be connected to an arrangement for indicating beats so as to facili tate adjustment of the'circuit.
  • an arrangement for indicating beats so as to facili tate adjustment of the'circuit.
  • FIG l such an arrangement is illustrated, and comprises a valve ll coupled as shown to the plate circuit of the heptode and giving anindicating output which may be taken from terminals 42.'
  • Figure 2r shows another embodiment .of the invention as applied to a superheterodyne receiver wherein self-tuning is resorted to.
  • a point (not shown) in the intermediate frequency amplifier of the receiver and from which intermediate frequency voltage is obtainable, is coupled through a condenser 43 to one end of a two-branch tuned circuit, the branches being designated A and B.
  • Branch A consists of a capacity 44a in series with an inductance 45a, and.
  • branch B which is in parallel with branch A likewise comprises series elements Mb and 45b.
  • the two branch circuit is tuned as a whole to the operating intermediate frequency, but one branch is arranged to be an acceptor circuit for a frequency above the operating intermediate frequency and; the other to be an acceptor circuit for a frequency a corresponding amount below the intermediate-frequency. For example, if the intermediate frequency is 100 kilocycles one branch may be tuned to 110 kilocycles and the other to. 90 kilocycles.
  • the junction of the inductance 45a and the capacity Na in branch A is connected through a rectifier 46afor example a copper oxide rectifier in series with a condenser shunted resistance combination 47a i80L---to that end of the two branch circuit remote from the coupling condenser 43, and in a similar manner the junction point of inductance 452) with capacity 44b is connected through a second rectifier 46b and a second capacity shunted resistance combination llb 58b to the same end of the two branch circuit.
  • Adjustable tapping points 49a and 4% upon the resistance 41a 41b respectively, are connected together through a further resistance 50,'and the mid-point of this.
  • the potentiometer resistance 38 which as in the previously described embodiment is shunted between the negative and positive terminals 83, ll, respectively, of a source of potential (not shown) the positive terminal of this source being connected, to the second grid 34 of the pentode andthe'tapping point 31 being connected to the cathode 35 of the pentode.
  • the cathode 35 is also connected as in. the usual way to the third or suppressor grid 36 of the pentode.
  • the anode 33 of the pentode is, as before, connected through a resistance 40 in series with a choke 39 to the positive terminal I 5 of a source of anode potential and a variable condenser 32 is connected between the control. grid 38v and the anode 33.
  • is connected by means of. terminals I3; 60, across the normally provided coil (not shown) in the adjustable frequency determining circuit of the local" oscillator of the receiver.
  • the local oscillator is manually adjusted as in the usual way, so as to beat with received signals to produce as nearly as possible the desired operating. intermediate frequency, but in a circuit as just described, owing to the interconnectionof the pentode with the local oscillator of thereceiver, if this manual adjustment is not accurately made, or if the received signal drifts somewhat in frequency, the local oscillator tuning will be, automatically varied in such, manner as to produce the correct operating intermediate frequency.
  • the intermediate frequency is accurately obtained at the point from which it is taken off to the two branch circuit, the potentials set up by the two rectifiers will be equal and the bias upon the first grid of the pentode will not be changed. faulty manual tuning or by reason of drift in the received signal frequency, the proper beat frequency is not obtained, the bias upon the pentode will be changed and this change will produce a variation in the effective reactance in the frequency determining circuit of the local oscillator.
  • the invention enables a rela- 1 tively narrow band pass intermediate frequency amplifier to be employed since accurate local oscillator tuning is automatically obtained, while furthermore, in receivers having automatic gain control the tuning indicator means usually deemed necessary to assist accurate manual tun ing, can be omitted.
  • This twobranch circuit is, as before, connected through a coupling condenser to the beat frequency ampliher; and the other end is connected to the cathode of a double diode triode iii.
  • a point between the inductance and capacity in one branch of the twobranch circuit is connected through a capacity shunted resistance combination 41a, 48a to one diode anode iter of the double-diode-triode tube 3i-this anode ta' is also connected to the grid 6?
  • adjustable tapping point 68 upon a further capacity shunted resistance combination 69, 10, which is in series between the cathode H of the doublediode-triode and the negative terminal l3 of an anode potential source.
  • the anode 12 of the double-diode-triode is connected through a resistance 13 to the positive terminal ll of the source of anode potential, and the mid-point of the resistance 50' is connected through a further resistance to the control grid 30 of the valve 3
  • the cathode 50 of this valve is connected as before to an adjustable tapping point 3'!
  • the invention is not limited to its application to heterodyne receivers and the principles embodied in the self-tuning super-heterodyne receivers described are applicable in like manner to securing self-tuning action against slight inaccuracies of tuning or slight signal frequency drifts in other types of receiversfor example, receivers embodying ordinary radio frequency tuned amplifiers.
  • a superheterodyne receiver of the type pro- Vided with an intermediate frequency energy circuit and a tunable local oscillator circuit whose frequency is to be automatically controlled the improvement which consists of a network comprising a pair of resonant circuit-s, each resonant circuit including a rectifier, means for impressing the intermediate frequency energy upon said resonant circuits, one of the resonant circuits being tuned to a frequency differing from the intermediate frequency by a predetermined frequency value, the other resonant circuit being tuned to a frequency differing from the intermediate frequency by the same frequency value but in,an

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Inductance-Capacitance Distribution Constants And Capacitance-Resistance Oscillators (AREA)
  • Burglar Alarm Systems (AREA)
  • Channel Selection Circuits, Automatic Tuning Circuits (AREA)
  • Superheterodyne Receivers (AREA)
US44045A 1934-09-14 1935-10-08 High frequency oscillating circuit Expired - Lifetime US2097937A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB26464/34A GB445543A (en) 1934-09-14 1934-09-14 Improvements in or relating to electrical high frequency oscillating circuit arrangements

Publications (1)

Publication Number Publication Date
US2097937A true US2097937A (en) 1937-11-02

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US44045A Expired - Lifetime US2097937A (en) 1934-09-14 1935-10-08 High frequency oscillating circuit

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US (1) US2097937A (enMihai)
BE (1) BE411275A (enMihai)
FR (1) FR794733A (enMihai)
GB (1) GB445543A (enMihai)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2429762A (en) * 1944-02-05 1947-10-28 Rca Corp Combined frequency modulation and amplitude modulation detector circuits
US2533496A (en) * 1946-04-18 1950-12-12 Motorola Inc Low-level bridge discriminator
US2773181A (en) * 1951-10-25 1956-12-04 Westinghouse Electric Corp Frequency discriminator system
US2794912A (en) * 1953-09-23 1957-06-04 Gen Electric Frequency modulation detector
US2836716A (en) * 1953-09-23 1958-05-27 Gen Electric Angle modulation detector

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
BE475237A (enMihai) * 1945-06-14
DE977658C (de) * 1945-09-07 1968-01-25 Rca Corp Detektor fuer phasenwinkelmodulierte Traegerfrequenzspannungen

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2429762A (en) * 1944-02-05 1947-10-28 Rca Corp Combined frequency modulation and amplitude modulation detector circuits
US2533496A (en) * 1946-04-18 1950-12-12 Motorola Inc Low-level bridge discriminator
US2773181A (en) * 1951-10-25 1956-12-04 Westinghouse Electric Corp Frequency discriminator system
US2794912A (en) * 1953-09-23 1957-06-04 Gen Electric Frequency modulation detector
US2836716A (en) * 1953-09-23 1958-05-27 Gen Electric Angle modulation detector

Also Published As

Publication number Publication date
FR794733A (fr) 1936-02-24
BE411275A (enMihai)
GB445543A (en) 1936-04-14

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