US2383855A - Potential ratio-controlled amplifier - Google Patents

Description

` Aug- Z8, 1945. c. w. HANsELL POTENTIAL RATIO-CONTROLLED AMPLIFIER lllll' Patented Aug. 28, 1945* STAT POTENTIAL nario-common@ 'l'f'i ilA e? ci.

Application December 10, 1942, Serial No. 4468,449

V(Cl. Z50-20) 14 Claims.

My present invention relates generally to circuits for obtaining control of the distribution of current between at least two electron collection electrodes, and more specifically to an electrically controlled device for controlling the distribution of current between a pair of -anodes substantially in accordance with the ratio of two controlled potentials, or currents, independently of their amplitude.

In my application Serial No. 469,647 led Dec. 21, 1942, I have disclosed and claimed various devices for controlling the division of acurrent into parts according to the ratio of two controlled curents. Briey, in that application the circuit arrangements function in accordance 'with theprinciple that when a magnetic eld in a Vacuum is made strong enough substantial electron motions can take place only in the directions parallel to the magnetic field. Any component of motion in other directions is overcome, because the magnetic eld bends the path of motion in these directions back to the axis from Ywhich they started. More specifically a pair of crossed magnetizing coils, within which there is located a cathode and an arangement of anodes, are provided, and the distribution of electron current to the anodes is-controlled by terms angular velocity-modulated carrier waves" and timing-modulated carrier waves are to .be understood as covering either frequency or phase modulated carrier waves, or combinations thereof. In this connection it is pointed out that frequency modulations of Aacarriei current in which the higher modulation frequency currents are emphasized or increased with respect to lower frequencies results in a type of modulation which is more accurately described as phase modulation than as frequency modulation. Thus, the above terms are intended to include any form of frequency modulation, or any form of phase modulation.

A still more speciiic object of my present invention is to provide frequency and phase modulation receivers without amplitude limiters, but having over-al1 characteristics similar to those v'obtainable through the use of limiters. In accomplishing this purpose I provide subsequently variations.

regulating the direction of the eld. The latter, f

in turn, is controlled by the ratio of currents in the magnetizing coils independently of the amplitude of these currents.

Accordingly, it' may be stated that it is one of the main objects of my present invention to provide a method of electrically controlling the Kdistribution of current between a pair of anodes in accordance with the ratio of two controlled potentials independently of their amplitude.

AIn my aforesaid application there is also disclosed the application of the electron current distribution method to a frequency, or phase, modulation receiver which does not employ a carrier -ing it unnecessary to apply a special amplitude limiter stage in a frequency modulation receiver. In this application, wherever used, the generic In using the phrase potential ratio-controlled I have assumed that the word ratio has no other dimension or significance than magnitude. Consequently, I wish it to be understood that the expression "potential ratio inherently signifies the ratio of magnitude of two potentials.

Other objects of the invention are to improve generally the simplicity and eiciency of fre-v quency and phase modulation receivers, but more especially to eliminate any need for an amplitude limiter.

The novel features which I believe to be characteristic of my invention are set forth in particularity in the appended claims; the invention itself, however, as to both its organization and method of operation will best be understood by reference to the following description, taken in connection with the drawing, in which I have indicated diagrammatically a circuit organization whereby my invention may be carried into etl'ect.

s In the drawing:

Fig. 1 shows a circuit embodying the invention. Fig. 2 is a partly sectioned view of the interior of an amplifier tube adapted for use in the circuit of Fig. 1,

Fig. 3 is a sectional view along line 3-3 of Fig. 2v looking inthe direction of the arrows,

Fig. 4 is a sectional view along line -B of Fig. 2, looking in the direction of the arrows.

Referring, now, to the accompanying drawing, wherein like reference characters in the different figures designate similar circuit elements, the circuit of Fig. 1 shows the invention applied to a frequencymodulated carrier wave (FM) receiver. More speciilcalLv. the potential ratio-controlled amplifier tube I is utilized subof frequency and phase modulated radio waves,

of which reception of FM radio broadcast programs is a common example, there are undesired amplitude modulations of carrier currents in the receivers which tend to add unwanted noise to the receiver output. These amplitude modulations usually are present because of hum'modulations in the transmitter; because of interfering radiations produced from the space circuit due to natural causes, or due to operation of electrical equipment of many kinds; because of hum and microphonic noises in the receivers; because of thermal agitation and shot effect noises in early circuits in the receivers; and because of insuflicient uniformity, or fiatness of response, of selective circuits within the frequency band occupied by the frequency and phase modulated waves and currents. In the prior art it has been customary to employ an amplitude limiter for removingamplitude modulations from the carrier current before the carrier current is applied to a frequency or a phase modulation demodulator. By removing amplitude modulations with a limiter it has been found possible to make a very substantial improvement in signal to noise ratio in the output of frequency and phase modulation receivers.

The following patents are given to illustrate .the state of the prior art of receiving frequency and phase modulated carrier waves. It is to be understood that the presently disclosed potential ratio-controlled amplifier circuit may be used in any of these prior systems. This inventionis of broad application, and may be utilized with other apparatus of widely varying characteristics including any of the prior systems described in the following patents. The latter are arranged in the order of filing of the respective applications: U. S. Patent No. 2,057,640, Conrad, filed Mar. 17, 1927; U. S. Patent No. 1,941,447-, Armstrong, filed May 18, 1927: U. S. Patent No. 1,819,508. Hansell, filed Aug. 11, 1927; U. S. Patent No. 1,794,932, Usselman. filed Sept. 1, 1927; U. S. Patent No. 2.013,847, Hansell. filed Oct. 2, 1928; U. S. Patent No. 1,803,504, Hansell. filed Oct. 5. 1928; U. S. Patent No. 1,867.567, Hansell.

led Feb. 1, 1929; U. S. Patent No. 1.941,069,'

Armstrong, filed Jan. 24, 1933; U. S. Patent No. 2.121.103, Seeley, led Oct. 17. 1935: U. S. Patent No. 2,180,736, Hansell, filed May 5, 1936: U. S. Patent No. 2 205,762. Hansell. filed Nov. 16, 1936; U. S. Patent No. 2,179,182, .Hansell. filed Nov. 27, 1936; U. S. Patent No. 2,207,541. Hansell, filed Jan- 18, 1939; U. S.,Patent No. 2,243,702, Hansell, filed May 19, 1939; and U. S. Patent No. 2,249,425, Hansell, filed Mar. 27, 1940.

The limiters of the prior art have usually been some sort of amplifier so designed, adjusted and operated that changes in input power gave little, if any, change in output power. These limiters required some input power level to be exceeded before a satisfactory hunting condition was reached, and often they showed a reduction in output power if the input power became relatively high. In designing limiters it has been found that the amplifier-limiter system preceding the demodulator must be capable of great over-al1 amplification, or increase of power, when weak signals are to be received. To provide for this turers, to avoid the cost, have sold frequency modulation receivers to the .public which omitted amplitude limiters even though such receivers do hors adequately suppress amplitude modulation no e.

In my application Serial No. 423,881, filed December 22, 1941, there are disclosed various types of demodulators for frequencyand phase modulation wvhioh when provided with a correct level of input power, are inherently unresponsive to the eil'ects of amplitude modulation so that no limiter is required. Inthe present application the frequency or phase modulation receiver may be of any of the prior systems noted, save that they do not include a special amplitude limiter prior to the detector. In accordance with my present invention the detector may be of any well-known form. Instead of constructing the demodulator to be inherently unresponsive to amplitude modulation, I provide an amplifier circuit subsequent to the demodulator, which ampli` fier circuit is unresponsive to the amplitude modulation. The demodulator tubes are shown as consisting of a pair of opposed diode rectiiiers 2 and 3. The FM signals. regardless of the source thereof, are applied to an input transformer I.

One end of the secondary winding of the transformer is connected to the junction of a pair, of series-related series resonant circuits. One of these series resonant circuits consists of condenser 5 and coil 6. The other series resonant circuit consists of coil 'I and condenser 8. 'Ihe junction of'coil 8 and 'l is connected to the aforementioned end of thel secondary winding of transformer 4. The anode of rectifier 3 is connected to condenser 5, and to the opposite end of the secondary Winding of transformer 4 through a resistor 9. Theanode of rectifier 2 is connected to condenser 8, and to the last mentioned end of the secondary winding throughv resistor I0.

The output load resistors of the rectifiers 2 and 3 are designated by numerals II and I2 respectively. Each of these load resistors is bypassed by an appropriate radio frequency by-pass condenser. The junction of resistors I2 and II is connected to the junction of coil 6 and 1. The

.Y v n '2,383,855 theArmstrong patent, the series resonant cirpotential, to the discriminator series resonant circuits within the signalling band, even though the series resonant circuits change impedancef with change Vof frequency. f

It has been stated before that the series resonant circuits -6 and '1 -8 are oppositely mistuned by substantially equal frequency amounts with respect to the center frequency Fc of the applied FM waves. While it is not believed necessary to give specific' frequency values, those skilled in the art know that for receiving standardized FM transmitters in the United States the frequency of circuit E-dmay be removed some '15 kilocyclesv (kc.) or more from Fc. The frequency of circuit 1 8 may be correspondingly located 'l5 kc. or more on the opposite side of Fc.- However, by tuning the series resonant circuits apart by a greater amount, and utilizing sufllciently broadly tuned circuits, less distortion in the demodulated output from the demodulator may be obtained. Thus, by broadening the circuit tunings and setting the tuning peaks further -apart in frequency in a manner to reduce the percentage differential response of the circuit to a given change of frequency, the distortion of the detector network output may be reduced. Additional infomation on this subject will be found in my application Serial No. 297,777 led vCoto-- ber 4, 1939, which is a division of my U. S. Patent 2,179,182 grantedNoVember 7, 1939.

Where the receiving system is of the superheterodyne type, which is the type universally anployed in present-day FM broadcast reception, the input circuits ofV the rectifierv tubes will be operating at a lower, or I. F., value. Such I. F. value would generally be chosen from a range of between 2 and 8 megacycles -(mc.) The assigned FM broadcast band in the United States at the present time is 42 to 50 mc., and the rmissible channel width is 200 kc. As is well known, a carrier is deviated a maximum of substantially 75 kc. to either side thereof, and, hence, in the Vbest receivers the inter-tube networks preceding the demodulator-are designed to transmit nearly equally a band width of approximately 15o kc plus twice the band width of the modulation frequencies. It will be understood that the primary circuit of input transformer li, which is magnetically coupled to the 'series resonant ciircuits, Vwill be tuned to Fc, but will be a broad band circuit capable of responding substantially equally to the whole signal band.

The primary circuit of transfermer t may be arranged in the anode circuit of the last I. F. amplier stage. It is not believed necessaryto detially constant current, for any constant input has imposed thereon amplitude modulation components. Therefore, injthe output circuit of the rectiflers, and prior to the input electrodes of tube l, there will appear the undesired amplitude modulation components. Nevertheless, the construction and functioning of tube i are such that in the output circuit thereof the amplitude mod-- ulation components will not appear, or will be of greatly reduced relative strength. It will be recognized that this is entirely different from the:

practice which has been followed in the priorart departedfrom'by the aforementioned instantane-l It is not believed necessary to explain the manner in which the detector functions. It is sufficient to point out that when the signal energy l il and l2 will have like polarity. When the in. stantaneous frequency of the applied signal en-Y erg-y shifts away from Fc, there will be developed across one vol the load resistors more rectified potential. Of course, that load resistor will have a. greater magnitude of rectied potential thereacross which corresponds to the series resonant input circuit whose resonant frequency is being ous frequency. In other words, for frequency deviation from Fc, the cathode ends of resistors H and l2 will be of like polarity, but of unlike magnitude. Of course. the carrier amplitude variations will affect both ends of resistors il and I2 to substantially the same percentage magni- It is to be understood that the present invention is applicable to any other type of balanced FM detector circuit. For example, the resistors Hand I2 could be placed in the output circuits of the demodulator disclosed in the aforementioned Usselman patent. Again, the resistors .could be placed in ,the outputfcircuits ofthe demodulator described'in the aforementioned Seeley patent. fr,

includes the potential ratio-controlled amplier. `The amplifier tube I is schematically represented in Fig. l. In Figs. 2, 3 and 4 the electrode structure thereof is more specifically shown. In general, the,tube l is of the type shown in my application Serial No. 324,053 filed March 15, 1940. y

However; there' are certain modications and improvements involved in the tube 'structure as well as in the use of the tube in this present application. v

Within the tube envelope of tube i there is provided an electron emission element i3, which 'has the electron stream therefrom passed scribed the networks between the conventional v signal collector and transformer 6, since these may follow standard FM broadcast superheterodyne receiver practice. Those skilled in the art are fully aware of the construction thereof. It is to beclearly understood that in the present case no amplitude limiter need be utilized in the system preceding the input to the demodulator at the primary winding of transformer 4. When no limiter is employed, it will be clear that there will be impressed upon the series resonant circuits 5-.6 and '--SV the FM waves whose carrier Y trodes 20 and 2l.

minal of potentiometer P. A ,shield electrode,

projects from the end I9 of cylindcr'electrode I8,

and acts as an electrical shield between elec- The cylinder I8 is connected t0 potential point I5, and hence, is at the same potential as anode Il. The forward end of cylinder I8 is open so that the electron beam readily passes through the open end into the field between electrodes Il and I6. The electrodes I'I is connected to the cathode end o! resistor I2 by condenser 30, while condenser 3I couples the electrode I6 to the cathode end of resistor II.

Resistor 32 is connected in shunt with load resistor II-I2, and between condnsers 30 and 3|.

'Ihe midpoint of resistor 32 is connected to a point 33 on P which is at a negative potential relative t0 point I5. Hence, the electrodes I'I and I8 are normally, and in the absence of applied signals, at an equal direct current potential which is less positive than point I5 and the positive end of potentiometer P. Before explaining the functioningr of the potential ratio-controlled amplifier circuit, the detail structure of the tube will be considered. As stated previously, the representation of tube IV in Fig. 1 is purely schematic. Hence, Figs. 2, 3 and 4 should be considered in connection with tube I.

'I'he tube envelope 40 may be made of glass, metal or other suitable material. Preferably, the envelope has a constricted section in which is located the electron emitter I3 and heater element I3'. The anode Il is shown as a hollow cylinder surrounding the emitter. 'I'he electrons are projected into the iiared main body of the tube through the aperture I4' in the forward end of the anode. The electrodes I6 and lI'I are each long rods, of circular cross-section. They diverge in the manner shown in Fig. 2. Leadsv Il' and I8' connect rods I'I and- I6 respectively to coupling condensers 30 and 3l. The numeral 50 denotes the electron beam which passes to the end I9 of the shield can I8. The can I9 is metal# lic, as are the rods I'I and I6. 'Ihe can I9 tag pers towards its open input end. Since the shield I8 is a hollow cylinder which envelopes the rods I1 and I6,1the closed end I9 has a circular shape.

'I'he end wall I9 is provided with a circular screen I9', 0r grid-like mesh, through which electrons may pass to the spaced collector electrodes and 2|. The screen has its wires preferably parallel to the direction of beam deilection. Across the diameter of the screen I9 is secured a lateral metallic, electric shield 23. 'Ihe latter is located 5between the collectors 20 and 2|. in spaced relation thereto. Each collector is a hollow box. One long side of the box is open, and spaced from the foraminous screen I9. The conductors from the collectors pass to respective opposite ends of the primary winding of audio transformer 22. Fig. 4 shows the relation between the electrodes when viewed from the collectors towards the emission electrode. The electrlc shield 23 extends beyond the limits of the spaced parallel collectors. The conductors from the collectors 20 and 2l are designated by the numeral BI. These conductors are connected to the respective ends of the primary winding of audio transformer 22.

Referring to Fig. 3 there is shown in cross-section the electrodes I8, II and I8, and the approximate coniiguration of an electric ileid between them. Flg. 3 shows how the enveloping cylinder- I8 surrounds the two Vrod-like electrodes I'I and I8. The electrodes Il and Il are indicated as negatively charged with respect to the cylindrical electrode I 8A With this arrangement as it is indicated in Fig. 3, there will be a region of substantially zero transverse electric field midway between the two rods IB and I'I. This region of zero 'transverse electric Ileld can be moved toward or away from each of electrodes I6 and Il by giving to the latter a diierence in negative potential. As has been explained previously, the electrodes I8 and I1 are connected to point 33 of potentiometer P, point 33 being asubstantially negative potential point.

Assume, now, that a stream of electrons is passing' along the axis of the cylindrical electrode I8 midway between the two rod electrodes I 8 and II. There will be substantially no tendency for the electron stream to be accelerated in any transverse direction so long as itis traveling in the region of substantially zero transverse electric field. However, if for any reason the stream is deilected toward one or the other of the rod-like electrodes, it will come within an electric iield which tends to return it to the line, or region, of zero electric ileld.

Therefore, to aiair degree of approximation,

when the potentials on electrodes I 6 and Il are angles to a line connecting the electrodes I6 and II'. In other words, the electron stream 50 is constrained to ow within the region o1' substan tially zero transverse electric eld. Accordingly, if we apply diierent electric potentials to the electrodes .I6 and I1, thereby deflecting the region oi' zero transverse electric field, the path which can be taken by the electron stream may be controlled. Within a large range of potentials this path may be made substantially independent of the total potentials upon the rod electrodes with respect to the cylindrical electrode I8, but dependent substantially upon their ratio. 'I'hat is why the amplifier I has been referred to as a potential ratio-controlled amplier.

Therefore, if the negative potential applied to each of electrodes I 6 and Il is obtained from one side of a balanced FM detector, it is possible to make the path taken by the electron streams substantially dependent upon the frequency of current input to a balanced FM detector, but nearly independent of the amplitude of signal input to the balanced detector. It is to be clearly understood that while I have shown a, particular type of amplifier tube construction for tube I, other types of tube structure operating on the same principles may be used. For example, any of the tube structures shown in my aforesaid pending aplication Serial No. 324,053 may be-utilized in place of the particular tube structure shown herein. Again, it is to be understood that the detail conilgurations of the electrodes I6, I1 and I8 are not essential, since other coniigurations may be utilized. For example, the rod elecaasaeas l Y organization shown and described, but that many 2modiiic'ations may be made without departing from the scope of my invention, as set forth in the appended claims.

What I claim is: 1. In combination with a detector of angular velocity-modulated carrier waves adapted to produce a pair of independent voltages which corre- Y spond to modulation of the carrier waves, and

which voltages are of like polarity relativeto a. common reference voltage point but of diierent 'magnitude,' an electron discharge tube comprising an electron emission element, a pair of elec- Y tron collector electrodes, a modulation voltage utilization circuit coupled to said `collector electrodes, means-conning the electrons emitted from said emission element to an electron beam projected toward said collector electrodes, at least two beam control electrodes in4 spaced relation on oppostie sides of said beam, said control electrodes divergi'ng in the direction of said collector electrodes, means for applying the aforesaid modulation voltages of differing magnitude to respective ones of said control electrodes, and means for maintaining said spaced control electrodes at a normal negative potential with respect to said collector electrodes whereby said electron beam is` constrainedto ow within a limited region between the two control electrodes.

A2. In combination with a detector of angular velocity-modulated carrier waves adapted to produce a pair of independent voltages which correspond to modulation of the carrier waves, and which voltages are of like polarity relative to a common reference voltage point but of different magnitude, an electron discharge tube comprising an electron emission element, a pair of electron collector electrodes.. a modulation voltage utilization circuit coupled to said collector electrodes, means confining the electrons emitted from said emission element to an electron beam projected toward said collector electrodes, at least two beam control electrodes in spaced relation on opposite sides of said beam, said control electrodes diverging in the direction of said collector electrodes, means for applying the aforesaid modulation voltages of differing magnitude to respectiv'e ones ofsaid control electrodes, means for maintaining said spaced control electrodes at a normal negative potential with respect to said collector electrodes whereby said electron beam is constrained to flow within a region midway between the two control electrodes, and a cylindrical electrode surrounding said spaced control electrodes, said cylindrical electrode being maintained at a positive potential with respect to the potentials of said spaced control electrodes.

3. In combination with a balanced frequency modulation' carrier wave detector adapted to provide 'a pair of independent modulation voltages of like polaritrr relative to a. common reference voltage point and diiering magnitude, an amplifier tube for said modulation voltage which is insensitive to carrier amplitude variation, said amplier comprising an lelectron emission element, means for producing an electron beam from electrons emitted from said element, a pair of spaced rod-like electrodes arranged on respectively opposite sides .of the electron beam and being divergent.. a pair of spaced collector electrodes, a modulation voltage utilization circuit connected in push-pull relation to said collector electrodes, a hollow cylindrical electrode enveloping said rodlike electrodes, means for maintaining the latter electrodes at a. negative potential relative to the enveloping cylinder vand said collector electrades whereby said-electron beam passes along the axis of the cylindrical electrode midway between the rod-like electrodes, and means for ap- Plyns the aforesaid modulation voltages to the l respective ones of said rod-like electrodes. said cylindrical electrode having the end thereofadjacent said collector electrodes provided-with an electron-transmitting screen. 4. In combination with a detector of angular velocity-modulated carrier waves adapted to produce a pair of'independent voltages which correspond to modulation of the carrier waves, and which voltages are of like polarity relative toa common reference voltage point but of diierent magnitude, an electron discharge tube compi'fis-A ing an electron emission element, a pair of electron collector electrodes. armoclulation voltage utilization circuit coupled to said collector electrodes, means conning tne electrons emitted from said emission element to an electron beam projected toward said collector electrodes, means for establishing an electric field which forces electrons in the beam toward a plane of minimum transverse electric eld, and means for applying the aforesaid modulation voltages of diiering magnitude to vary the electric iield for varying the position of the plane. l x

5. In combination with a'detector of angular velocity-modulated carrier waves adapted to produce a pair of independent voltages which correspond to modulation of the carrier Waves, and which voltages are of like polarity relative toa y common reference voltage point but of different magnitude, an electron discharge tube comprising an electron emission element, a pair of electron collector electrodes, a modulation voltage utilization circuit coupled to said` collector electrodes. means conini'ng the electrons emitted from said emission element to an electron beam projected toward said collector electrodes, at least two divergent control electrodes in spaced relation on opposite sides of said beam, means for applying the aforesaid modulation voltages `of diiering magnitude to/respective ones of said control electrodes, means for maintaining said'spaced control electrodes ata potential with respect tosaid collector electrodes whereby said electronbeam is constrained to now within a region midway between the two control electrodes, a .cylindrical y electrode surrounding said spaced control electrodes, and said cylindrical electrode being maintained/ at a. positive potential with respect to the potentials of said spaced control electrodes.

6. In combination with a detector of frequency modulated carrier waves adapted to produce a pair of independent voltages which correspond to modulation of the carrier waves, and which voltages are of like polarity relative to a common reference voltage point but of different magnitude, an electron discharge tube comprising an electron emission element, a pair of electron collector electrodes, a modulation voltage utilization circuit coupled to said collector electrodes, electrons emitted from. said emission element being in the region thereby to deflect the position of the beam.

7. In combination with a balanced detector oi frequency modulated carrier waves adapted to lproduce voltages of differing magnitude whlch correspond to modulation of the carrier waves, an electron discharge tube comprising an electron emission element, a pair of collector electrodes, a modulation output ciruitcoupled to said collector electrodes, meaiisk'ning the electrons emitted from said emission element into an electron beam projected toward said collector electrodes,- at least two control electrodes in spaced relation on opposite sides of said beam, said control electrodes diverging towards said collector electrodes, means for applying the aforesaid modulation voltages to respective ones of said control electrodes, and means for maintaining said spaced control electrodes at a potential with respect to said collector electrodes such that Said electron beam is constrained to flow within a limited reslon between the two control electrodes.

8. In combination with a source of a pair of independent voltages of like polarity relative to a common reference voltage but of diilerent magnitude, an electron discharge tube comprising an electron emission element, a pair of electron co1- lector electrodes, an output circuit coupled to 'said collector electrodes, means confining the electrons emitted from said emission element to an electron beam projected toward said collector electrodes,

' at least two beam control electrodes in spaced relation on opposite sides of said beam, said control electrodes diverging in th'e direction of said collector electrodes, means for applying the aforesaid voltages of diilering magnitude to respective ones of said control electrodes, means for maintaining said spaced control electrodes at a normal negative potential with respect to said collector electrodes whereby said electron beam is constrained to flow within a region midway Abetvveen the two control electrodes, and a cylindrical electrode surrounding said spaced control electrodes, said cylindrical electrode being maintained at a positive potential with respect to the potentials of said spaced control electrodes.

9; In an ampliiier system which is insensitive to current amplitude variation, an electron emission element, means for producing an electron beam from electrons emitted from said element, a pair of spaced rod-like electrodes arranged on respectively opposite sides oi' the electron beam and being divergent, a pair of spaced collector electrodes, a voltage output circuit connected in pushpull relation to said collector electrodes, a hollow cylindrical electrode enveloping said rod-1ike electrodes, means ior maintaining the latter electrodes at a negative potential relative to the enveloping cylinder and said collector electrodes whereby said electron beam passes along the axis of the cylindrical electrode midway between the rod-like electrodes, means for applying voltages to be amplied to the respective ones of said rodlike electrodes, said cylindrical electrode having the end thereof addacent said collector electrodes provided with an electron-transmitting screen.

10. -In combination with a balanced frequency -modulation detector, an amplier insensitive to amplitude variation oi detected voltages, said ampller including a pair of spaced rod-like elecaplane of minimum electric iield'in directions transverse to the general direction of the beam,

and means to vary th'e ratio of the potentials.

11. In combination, an electron discharge tube comprising an electron emission element., a pair of electron collector electrodes; a signal voltage utilization circuit coupled to said collector electrodes, electrons emitted i'rom said emission element being inthe form of an electron beam projected toward said collector electrodes, means for establishing a region of lowtransverse electric neld through which said -beam is constrained to pass, and means for utilizing signal voltages of diii'ering magnitude to move the position of the region thereby to ideilect the position of the beam. r

l2. In a receiver of angular-velocity modulated carrier waves, a demodulator for producing a pair of independent modulation voltages from said waves, anv ampliiler following the demodulator,

. said amplifier including means to provide an electron beam.,v means for establishing a region of low transverse electric field through which said electron beam is constrained to pass, and means responsive to said voltages to move the position of the region to deect the position oi' the beam.

13. In combination with a detector of angular velocity-modulated carrier waves adapted to produce a pair of independent voltages which correspond to modulation of the carrier waves, and which voltages are of like polarity relative a reference vol-tage .point but of diiterent magnitude, an electron discharge tube comprising an electron emission element, a pair of electron collector electrodes, a modulation voltage utilization circuit coupled to said collector electrodes, means for establishing an electric field which forces electrons inthe beam toward a plane of minimum transverse electric eld, and means for varying the electric iield in response to said voltages for varying the position of the plane.

14. In an electronic system, means' adapted to provide at least two potentials, an electron vacuum tube including means for producing a beam of moving electrons. means i'or establishing a, configuration of electric elds within said tube which tend to determine the path' of the electrons and to oppose any motions away from said path, at least two spaced electrodes responsive respectively to said potentials for modifying the coniiguration of the electric elds to bend the path, at least two anodes in said tube for collecting the electrons with a distribution of numbers between the anodes which is determined by the bending of the patiiA in response to the ratio of said two

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