US2447309A - Tuning indicator system - Google Patents

Tuning indicator system Download PDF

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Publication number
US2447309A
US2447309A US625159A US62515945A US2447309A US 2447309 A US2447309 A US 2447309A US 625159 A US625159 A US 625159A US 62515945 A US62515945 A US 62515945A US 2447309 A US2447309 A US 2447309A
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Prior art keywords
tuning
signal
indicator
receiver
tube
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Expired - Lifetime
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US625159A
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English (en)
Inventor
Harold L Blaisdell
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Hazeltine Research Inc
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Hazeltine Research Inc
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Priority to BE468765D priority Critical patent/BE468765A/xx
Application filed by Hazeltine Research Inc filed Critical Hazeltine Research Inc
Priority to US625159A priority patent/US2447309A/en
Priority to FR935074D priority patent/FR935074A/fr
Priority to GB31830/46A priority patent/GB635064A/en
Application granted granted Critical
Publication of US2447309A publication Critical patent/US2447309A/en
Priority to DEH5367A priority patent/DE889614C/de
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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03J—TUNING RESONANT CIRCUITS; SELECTING RESONANT CIRCUITS
    • H03J3/00—Continuous tuning
    • H03J3/02—Details
    • H03J3/12—Electrically-operated arrangements for indicating correct tuning
    • H03J3/14—Visual indication, e.g. magic eye

Definitions

  • the present invention relates-to tuning indicator systems for Wave-signal 'receivers and, 'particularly, to such systems for indicating the degree of mistuning of the receiver oneither side ofja received Wave signal or for indicating ⁇ the degree and direction of such-mistuning.
  • Wave-signal receivers conventionally are pinovided with adjustable tuningelementsbywhich the receiver may be tuned toy a desiredWave sig- Tuning indicator systems
  • Eheretofore Aus'edior ⁇ proposed for amplitude-modulation -receiversinl clude some device for visually indicating thelmagnitudeof a unidirectional current or voltagederived from the wave signal translated by .ther-e'- DCver and varying with its amplitude.
  • a tuning indicator system for ,awaver signal. receiver :including an 'adjustable z tuning means, comprises an inputicircuitadapted t9' have .applied thereto-a unidirectional control signal ,the -magnitude ofcwhich ⁇ varies VWith the degree .of
  • the system includes .meansfor deriving a control effect, themagnitudeoi which varies muchless rapidlyrwith the aforesaid degl-leof Imistuning than .doestheaforesaid control vvSignal,
  • a complete frequency-modulation' wave-signal receiver of a conventional#design unidirectional tuning control signal the magnitude of which varies with the degree of mistuning of the receiver on either side of the received Wave signal and the .polarity of which varies with the direction of such mistuning.
  • the control signal applied tothe input terminals 20 also varies with the intensity of the wave signal for all values thereof less than the limiting level.
  • This condition occurs, for example, when receiv- Aing -wave signals from comparatively distant transmitting stations.
  • the receiver is shown as including a tun-Vi able radio-frequency amplifier I having an in? ⁇ put circuit coupled to an antenna system II, I2 and having an output circuit coupled to a tunable frequency lchanger or oscillator-modulator I3.
  • an intermediatefrequency amplier I4 Connected in cascade with theA oscillator-modulator I3, in the order named, are an intermediatefrequency amplier I4, a combined single-stage or multi-stage intermediate-frequency lampliiier and automatic-volume-control or A. V. C.
  • a tuning indicator system includes a tuningy indicatory device I9 is coupled to the output circuit of the frequency detector I6.
  • the automatic-,volume-control supply of unit I5 has an output circuit, designated as A. V. C., coupled to the input circuit of one or more of the .tubes of units I0, I3, I4, and I5.in conventional manner.
  • a desired frequency-modulated wave signal is selected andamplied by the'tunable radiofrequency amplifier I0, converted to a frequencymodulated intermediate-frequency Wave signal in the oscillator-modulator I3, amplified in the intermediate-frequency amplifiers I4 and I5, and detected by the frequency detector IE, thereby to derive the audio-.frequency modulation components thereof.
  • the audio-frequency components are in turn, amplified in the audio-frequency amplifier I1 and are reproduced by the sound reproducer I8 in conventional manner.
  • An auto- -matic-volume-control or A. V. C. bias derived by the A. V. C. supply system of unit I5 is effective to control the amplification or gain of one or more of the units I0, I3 or I4 to maintain the signal input to the detector I6 within a relatively narrow range for a' widerange of received signal intensities.
  • the tuning indicator system includes an input circuit, comprising input-circuit terminals 20,v adapted to have applied thereto-'a kintermediate-frequency 'ampliiier cludes a vacuum-tube repeater 34 having input 'ofxapproximately the same magnitude for reception from such stations as for reception from less distant stationswhich, because of the larger intensities of their received wave signals, cause amplitude limiting to be effected by :the limiter.
  • the tuning'indicator system also includes the tuning indicator I9 which is coupled through an amplier and phase inverter 2l to the input terminals 20 and is responsivev to the tuning control signal applied thereto for indicating the degree and direction of mistuning of the receiver to the received wave signal.
  • the indicator I9 is of the cathode-ray tube type having an anode or target electrode 22 and including input electrodes comprising a cathode 23 and a .pair rof cathode-ray beam deiiecting electrodes 24 and 25.
  • the deflecting electrodes 24 and 25 of the indicator tube I9 are directly connected respectively to a screen electrode 26y and an anode 21 of tube 2 I the screen electrode 26 and anode 2l being energized from a source of potential, indicated as +B, through respective resistors 28 and 29.
  • includes a pair of input electrodes, comprising a suppressor electrode 30 and a cathode 3l, which are coupled through a lter network including aseries-arm resistor 32 and a shunt-arm condenser 33 to the input-circuit terminals 20.
  • the indicator system thus far described is of the type shown and described in the United States Letters Patent No. 2,294,182, granted August 25, 1942 to Robert T. Hintz, for Tuning indicator for carrier-signal receivers, and assigned to the same assignee as the present invention.
  • the ⁇ tuning indicator system of the present invention also includes means for deriving a control effect, the magnitude of which over the pass band of the receiverl varies much less rapidly with the degree of mistuning of the receiver than does the aforementioned control signal, and for utilizingthe control effect to vary inversely with the intensity of the received Wave signal, by variation of the energization of the anode or target electrode 22 of the indicating tube I9, the sensitivityof response of the indicator I9 to the tuning control signal applied to the input-circuit terminals 20 to reduce the sensitivity of indication of the tube IS with increasing intensities of the received-wave signal.
  • This means comprises the I4 which inelectrodes, including a control electrode 35, coupled through a double-tuned band-pass selector 36 to the output circuit of the oscillator-modulator I3.
  • the repeater 34 has an anode 31 coupled'through adouble-tuned band-pass selector asto the input circuit 'df the' intermediate-rre;
  • control eiect to vary inversely with the intensity, of a receivedfwave Asignal an operating characteristidnamely the transconductance, of
  • the repeater 34 *thereby correspondingly to vary the-gain of theA amplifier I4.
  • the indicator' sensitivitycontrol means additionally includes means responsive to variationsiof the operating lcharacteristic of repeater 34, namely, to variations of its transconductance orto variations of; gain ofthe amplier' ,14; for' controlling in accordance therewithithe sensitivityoff responseoi the indicator tuberi 9 t'ojthe tuningk controlpotential applied to thejinputstcrminalsii to, reduce the sensitivity oi" indicationofth'e indicator tube lil with increased intensitiesV of the received Wave signal.
  • Arustic of the 4frequency detector IS is representedby curve C-Vfora-received Wave signal of n GDSY andbyicu'rve D for a' Wave signal Y Y elybvweal; intensity, the detectorrcharac r1 icthus being of the familarS congurat'ionfcenteredfuponand varying rapidly in the region of the mean resonant frequencyffu of the receiver.
  • VvThe last-.mentioned means 6 frequency' fo'.'
  • the audio-frequency filter 32, t33 ⁇ renovs any audio-.frequency modulation' components rdevelopedin the output circuit of VtheV ⁇ frequency detector I-Gf'andfrsin-ce tlieiaveragefoutputlpotential of the detector isthen zero as indicated'by either of the curves C or.
  • D ⁇ no unidirectional tuning-control signal is applied to theinputele'c'- trodes 3), 3l of theY tube -2
  • Thezout'- put of the Vfrequency detector iii ⁇ novv hasan averagev unidirectional component of potential the magnitude of which is dependent rupon-'tite degree of mistuningf and ythe polarity of which i's dependent uponthe direction' of Inistu'ning.
  • the audio-frequency filter v32 k(i3-removes the audio-frequency modulation corn-poe nents so that onlythe unidirectionalzcomponent alone is applied to the input electrodes 30; lfof the tube 2l.
  • the automatic-amplillcation-control or A. V. C. bias derived from the A. V. C. supply of unit I5 is applied through the lter 39, 40 to the control electrode 35 of the vacuum-tube repeater 34 so to vary its gain, in conjunction with a similar variation of gain of units I or I3 as to maintain the signal input to the frequency detector I6 within a relatively narrow range for a Wide range of received signal intensities.
  • the A. V. C. bias reduces the space current of the screen electrode 4I of the repeater 34 with increasing intensities of the received wave signal.
  • electrode 4I varies' directly with the intensity of the received wave signal.
  • the anode or target electrode 22 of the indicator tube I9 is energized, through the ener gizing circuit 44, from the screen electrode 4l of the receiver 34. It will thus be apparent that the positive energizing potential applied to the target electrode 22 of the indicator tube 9 also varies directly with the intensity of the received wave signal.
  • the value of the screen resistor 42 of the amplier I4 is so selected with relation to the screen potential +Sc and the characteristics of the tubes 34 and I9 that the response characteristic ofthe indicator tube I9 would be that represented by the broken-line curve M of Fig'. 3 if the changes of target-electrode potential and changes of tuning control signal appliedvto the tube 2
  • A. V. C. bias has a value which varies, with 'the tuning of the receiver, as represented by'curves A or B of Fig. 2.
  • the A. V. C. bias is .thus sub--v stantially constant over the frequency'range f1 to f2, whereas the tuning control signal varies rapidly in magnitude on either side of the 'frequency fo and over the frequencyrange f1 to .f2.-
  • the constant value of A. V. C. bias developed over the frequency range f1 to f2 results in a constant value of energization of.
  • the target electrode 22 of the indicator tube I9 the exact value ofenergization varying with the intensity of the received wave signal as hereinbefore4 pointed out, so that over this frequency range the latter tube operates with a response sensitivity Lrepresented by one of its characteristic curves J, K, E or L of Fig. 3.
  • the tuning control signal applied to the tube 2I varies over the frequency range f1 to ,f2 in accordance with the characteristie curves C or D of Fig. 2 depending upon the received signal intensity
  • the entire tuning indication provided by the tube I9 over the same frequency range follows along one of the-characteristic curves J, K, E or L of Fig. 3 from the 90- degree shadow-angle value to a minimum lshadow-angle value at'which the particular .sensitivity curve intersects the broken-line curve M.v
  • the tuning indications thus provided enable as high an ⁇ accuracy of tuning of the receiver to WaveA signals of weak intensity as to Wave signals of strong intensity, particularly in that the maximum response of the indicator system need no longerbe reserved, as heretofore necessary, for the highest intensity wave signal to be encountered in the operation of the receiver.
  • Fig. 5 is a circuit diagram, partly schematic, of a portion of a Wave-signal receiver of the amplitude-modulation type embodying ⁇ the present invention in a modied form.
  • the present are' rangement is essentially similar to that of Fig, 1,'
  • the tuning indicator tube I9' ofthe present .arrangement is of Aaftype conventionally us'ed in amplitude-modulation'relceivers and may, for example, vbe of the 6E5 type which includes a triode section comprising a cathode 23.', a control electrode 45, and ananode..
  • the anode hasv internally connectedftheretoa defiecting electrode 24 and the indicator tube Vincludes a target .electrode 22' .cooperating With'the deilecting electrode.
  • the anode 46 is connected to the target .electrode V22 through a resistor 41- and the target electrode is energized through the that of theoverallband-.pass characteristicof thereceiver.forpexample a pass band of tWofor three kilocycles Where the receiver passband is ,kilocycles.
  • the resonant ycircuit 43 The resonant ycircuit 43.
  • the resistor 52 preferably has avalueof resist-i ance Aof several megohms so that it does noteppreciablyload, and thereby decrease the Q;of,
  • the condenser 53 has ⁇ the resonant. circuit 49. suflicient capacitance that the time constant of this condenser and the resistor 52 is long in comparison With the period of the lowest-,frequency modulation component of the received Wave signal so that the modulation components are 4effec,-
  • curve N represents the band-pass characteristic of the receiver .-for a received Wave signal of relatively strong intensity andj curveO that for a receivedl Wave signal of relatively Weaklintensity.
  • This band-pass characteristic isassumed to have a relatively broad andnearly. at top over the frequency range f1. to fz centered upon the mean intermediate frequency/fo".
  • the band-pass character-,- istic of;the resonant vcircuit IltisV represented by the curve-P, Fig. 6for a received Wave; signal o-strong intensity and by curve Rifor a received Wave lsignal of relatively Weak intensity. Itwill. bessen that .the resonant. circuit 4.9 .is .tuned to...
  • the A.YV. C. bias developed by the A. V. C. supply of unit I6 has a value Which, as the receiveris ytuned across a given received Wave signal, varies in accordance with Vthe Aband-pass characteristic .of the receiver. VvIt'vvill be thus apparent that curves N and fO :also'represent (the magnitude o'i A. V. C. lbias developed, Withituning of-t'he receiver, respectively to a strong ⁇ wave signal and to a weak Wave signal.
  • This A. V. C. bias so controls the' potentials of the .screen elec.- trode el :of-the tube 3'4 'andof the target electrode 22".
  • the target electrode *22'l andi anode'46 'of-the indicator -tube- I9 remain; substantially ⁇ constant plained in'y connection withV vthe operation "of- ⁇ the.
  • the ⁇ tuning -signalf'supply system4'8 rectifies the Wave-signal energyv .applied thereto 'from the outputcircuit-of ⁇ the intermediatefrequencyam? plier l5 to develop across its load-impedance 52.53 a unidirectional potential or tuningsign'al, free from modulation*component/s, which' ris 'ap-.- plied to ⁇ the control:V electrode 4510i the indicator tube?
  • circuitcomponen-osg ot the .tuning indicator zsystem may. beaso,4 selected..
  • the anode 46 of the indicator tube I9 is also energized from the screen electrode 4
  • the A. V. C. supply of unit i6 be of the conventional delay-bias type.
  • the value of delay bias to be used is established with relation to the intensity of a relatively weak intensity Wave signal such as thatl which causes operation of the indicator tube IS along curve J of Fig. 3.
  • the value of delay bias used is preferably such that no A. V. C. bias is developed by the A. V. C. supply of unit I6 until the shadow angle of tube I9' has closed to approximately 45 degrees'while tuning the receiver toward the wave signal.
  • Fig. 7 is acircuit diagram, partly schematic, representing an additionally modied form of the invention essentially similar to that of Fig. 5. Similar circuit elements are designated by similar reference Anumerals and analogous elements by similar reference numerals double primed.
  • the indicating device I9" of the present arrangement comprises an indicating meter. The latter has a held-energizing Winding 54 included in the cathode circuit of the vacuumt'ube repeater 34 and has a movable winding 55 mechanically connected to an indicating needle y58 Yand coupled to the tuning signal supply 48.
  • a tuning indicator system embodying the invention hasv an indicating sensitivity varying inversely with the intensity of a received wave signal so that it provides approximately the same magnitude of indication over a. wide range of received wave signal intensities.
  • the tuning indicator system of the invention has the additional advantage that it is of simple and inexpensive circuit arrangement involving a minimum of circuit components.
  • A'tuning indicator system for a Wave-signal receiver including an adjustable tuning means comprising, an input circuit adapted to have applied thereto a control signal the magnitude of which varies with the degree of mistuning of said receiver over individual tuning ranges on either side of a received Wave signal, a tuning indicator coupled to said input circuit and responsive to said control signal for indicating said degree of mistuning, and means for deriving a control effect the magnitude of which varies much less rapidly with said degree of mistuning than does said control signal and for utilizing said control effect to vary inversely With the intensity of said received Wave signal the sensitivity of response of said indicator to said control signal to reduce the sensitivity of indication thereof with increasing intensities of said received Wave signal.
  • a tuning'indicator system for a wave-signal receiver including an adjustable tuning means comprising, an input circuit adapted to have applied thereto a control signal the magnitude of which varies both with the intensity of a received Wave signal and with the degree of mistuning of said receiver over individual tuning ranges on either side of said received Wave signal, a tuning indicator coupled to said input circuit and responsive to said control signal for indicating said degree of mistuning, and means for deriving a control effect the magnitude of which varies with the intensity of said received wavesignal but variesmuch lessrapidly with said ⁇ degree ofrrmi'stuning than does said control signal andfor utilizing said control effect to vary inversely with the magnitude thereof the sensitivity. of response of said indicator to said control signal to reduce the sensitivity of indicationthereof with increasing intensities of said received wave signa-l.
  • a tuningindicator system for a Wave-signal receiver including an adjustable tuning means comprising, an input circuit adapted to' have applied thereto a control signal the magnitude andv polarityv of which vary with the degree and direction, respectively, of mistuning of said receiver over individual tuning ranges on either side of a received wave signal, a tuning indicator coupled to said input circuit and responsive to said control signal for indicating said degree and direction of mistuning, and means for deriving a control eiect the magnitude of Which varies much lessrapidly with said degree of mistuning than does saidcontrol signal and for utilizing said control effect to vary inversely with the intensity of said received Wave signal the sensitivity of response of said indicator to said conor trol signal to reduce the sensitivity of indication thereof with increasing intensities of said received 'Wave signal.
  • a tun'ingindicator system for a Wave-signal receiver including an adjustable tuning means comprising, an input circuit adapted to have applied thereto a control signal the magnitude of which varies with the degree lof mistuning of said receiver over individual tuning ranges on either side of a received Wave signal, a cathode-ray tube tuning indicator having input electrodes coupled to said input circuit and responsive to said control signal for indicating said degree of mistuning, and means for deriving a control effect the magnitude of.
  • a tuning indicator system for a wave-signal receiver including an adjustable tuning means comprising, an input circuit adapted tol have applied thereto a control signal the magnitude of which varies with the degree of mistuning ⁇ of said receiver over individual tuning ranges on either side of a received Wave signal, a cathode-ray tube tuning indicator having an anode and including input electrodes coupled to said input circuit and responsive to said control signal for indicating said degree of mistuning, and means for deriving a control effect the magnitude of which varies much less rapidly with said degree of mistuning than does said control signal and for utilizing said control effect to vary inversely with the magnitude thereof the energization of said anode to reduce the sensitivity of indication of said indicator with increasing intensities ⁇ of said received Wave signal.
  • a tuning indicator system for a Wave-signal receiver including an adjustable tuning means comprising, an input circuit adapted to have applied thereto a control signal the magnitude oi which varies with the degree of mistuning .of said receiver over individual tuning ranges on either side of a received wave signal, a Icathode-ray tube tuning indicator having a cathode-ray target elecdoes said control signal and for utilizing said.
  • control effect to vary inversely With the intensity of said received wave signal the energization of target electrode to reduce the sensitivity nf indication of said indicator with increasing ntensities oi said received Wave signal.
  • a tuning indicatorsystem for a Wave-signal receiver including an adjustable tuning means comprising, an input circuit adapted to have applied thereto a control signal the magnitude of which varies with the degree of mistuning of said receiver over individual tuning ranges on either side oi a received Wave signal, a tuning indicator coupled to said input circuit and responsive to said control signal for indicating said degree of mistuning, a vacuum-tube repeater, means for deriving a control effect the magnitude of which varies much less rapidly with said degree of mistuning than does said control signal and for Autilizing said contnol leffect to vary inversely-withv the intensity of said received Wave signal an operating characteristic of said repeater, and means ⁇ responsive Vto variations of said operating characteristic for controlling in accordance therewithl the sensitivity of response of said indicator to said control signal to reduce the sensitivity of indication thereof with increasing intensities of said plied thereto a control signal the magnitude of y which varies with the degree of mistuning of said receiver over individual tuning ranges oneithert side of a
  • a tuning indicator system for a Wave-signal receiver including an adjustable tuning means comprising, an input circuit adapted to have applied thereto a control signal the magnitude of which varies with the degree of mistuning of said receiver over individual tuning ranges on either side o'f a received Wave signal, a tuning indicator coupled to said input circuit and responsive to said control signal for indicating said degree of mistuning, -a vacuum-tube repeater having a positively energized electrode, means for deriving a control effect the magnitude of which varies much. less rapidly with said degree of mistuning than does said.
  • control signal and for utilizing said control eiect to vary inversely with the intensity of said received Wave signal the energization of said electrode, and an energizing circuit for energizing said indicator from said positively energized electrode to vary inversely with the intensity of said received Wave signal the sensitivity of response to said indicator to said control signal to reduce the sensitivity of indication thereof with increasing intensities of said received Wave signal.
  • a tuning indicator system for a Wave-signal receiver including an adjustable tuning means and a gain-controllable Wave-signal amplier comprising, an input circuit adapted to have applied thereto a control signal the magnitude of which varies with the degree of mistuning of said receiver over individual tuning ranges on either side of a received Wave signal, a tuning indicator coupled to said input circuit and responsive to said control signal for indicating said degree of mistuning, means for deriving a control effect the magnitude of which varies much less rapidly with said degree of mistuning than does said control signal and for utilizing said control effect to vary inversely7 With the intensity of said received Wave signal the gain of said ampliiier, and 'means responsive to variations of the gain of said amplier for controlling in accordance therewith the sensitivity of response of said indicator to said control signal to reduce the sensitivity of indication thereof with increasing intensities of said received Wave signal.
  • a tuning indicator system for a Wave-signal receiver including an adjustable tuning means and having a relatively broad band-pass characteristic for received wave signals comprising, an input circuit adapted to have applied thereto a control signal the magnitude of Which over at least the central portion of said band pass of said receiver varies rapidly With the degree of mistuning of said receiver over individual tuning ranges on either side of a received wave signal, a tuning indicator coupled to said input circuit and responsive to said control signal for indicating said degree of mistuning, and means for deriving a control eiect the magnitude of which over said pass band of said receiver varies much less rapidly with said degree of mistuning than does said control signal and for utilizing said control effect to vary inversely with the intensity of said received Wave signal the sensitivity of response of said indicator to said control signal to reduce the sensitivity of indication thereof with increasing intensities of said received Wave signal.
  • a tuning indicator system for a vWave-signal receiver including an adjustable tuning means and having a relatively broad fband-pass characteristic for received Wave signals comprising, means including a sharply resonant circuit having a lband-pass characteristic substantially less than that of said receiver for deriving a control signal the magnitude olf Which over at least the central portion of said pass band of said receiver varies rapidly with the degree of mistuning of said receiver over individual .tuning ranges on either side of a received Wave signal, a tuning indicator coupled to said means and responsive to said control signal for indicating said degree of mistuning, and means for deriving a control effect the magnitude of which over said pass band of said receiver varies much less rapidly with said degree of mistuning than does said control signal and for utilizing said control effect to vary inversely with the intensity of said received wave signal the sensitivity of response of said indicator to said control signal to reduce the sensitivity of indication thereof with increasing intensities of said received wave signal.

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  • Circuits Of Receivers In General (AREA)
  • Input Circuits Of Receivers And Coupling Of Receivers And Audio Equipment (AREA)
US625159A 1945-10-29 1945-10-29 Tuning indicator system Expired - Lifetime US2447309A (en)

Priority Applications (5)

Application Number Priority Date Filing Date Title
BE468765D BE468765A (enrdf_load_stackoverflow) 1945-10-29
US625159A US2447309A (en) 1945-10-29 1945-10-29 Tuning indicator system
FR935074D FR935074A (fr) 1945-10-29 1946-10-23 Dispositif indicateur de syntonisation dans les radio-récepteurs
GB31830/46A GB635064A (en) 1945-10-29 1946-10-26 Tuning indicator system
DEH5367A DE889614C (de) 1945-10-29 1950-09-19 Abstimmanzeiger fuer drahtlose Empfangsgeraete

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US625159A US2447309A (en) 1945-10-29 1945-10-29 Tuning indicator system

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US2447309A true US2447309A (en) 1948-08-17

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US (1) US2447309A (enrdf_load_stackoverflow)
BE (1) BE468765A (enrdf_load_stackoverflow)
DE (1) DE889614C (enrdf_load_stackoverflow)
FR (1) FR935074A (enrdf_load_stackoverflow)
GB (1) GB635064A (enrdf_load_stackoverflow)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2630527A (en) * 1948-11-24 1953-03-03 Rca Corp Interchannel noise suppressor circuits
US3571714A (en) * 1968-09-12 1971-03-23 Grundig Emv Lamp arrangement for combined tuning indication and silent tuning in high-frequency receivers

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE925181C (de) * 1952-10-10 1955-03-14 Siemens Ag Schaltungsanordnung fuer Abstimmanzeigeroehren, insbesondere in Rundfunk- und Fernsehempfaengern

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2164979A (en) * 1937-06-04 1939-07-04 Telefunken Gmbh Tuning indicator circuit
US2334473A (en) * 1941-08-07 1943-11-16 Rca Corp Frequency modulation tuning indicator

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NL50144C (enrdf_load_stackoverflow) * 1937-04-21

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2164979A (en) * 1937-06-04 1939-07-04 Telefunken Gmbh Tuning indicator circuit
US2334473A (en) * 1941-08-07 1943-11-16 Rca Corp Frequency modulation tuning indicator

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2630527A (en) * 1948-11-24 1953-03-03 Rca Corp Interchannel noise suppressor circuits
US3571714A (en) * 1968-09-12 1971-03-23 Grundig Emv Lamp arrangement for combined tuning indication and silent tuning in high-frequency receivers

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DE889614C (de) 1953-09-10
FR935074A (fr) 1948-06-09
BE468765A (enrdf_load_stackoverflow)
GB635064A (en) 1950-04-05

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