US2431396A - Current magnitude-ratio responsive amplifier - Google Patents

Description

CURRENT MAGNITUDE-RATIO RESPONSIVE AMPLIFIER ...nn-nu.- n n-...nu

Nov. 25, .1947. c. w. HANsELL 2,431,396

CURREN' MAGNITUDE-RATIO RESPONSIVE AMPLIFIER Filed Deo. 21, 1942 2 sheets-sheet 2 TTONEY Patented Nov. 25, 1947 CURRENT MAGNITUDE-RATIO RESPONSIVE AMPLIFIER Clarence W. Hansell, Port Jefferson, N. Y., assig'nor to Radio Corporation of America, a corporation of Delaware Application December 21, 1942, Serial No. 469,647

(Cl. Z50-27) 21 Claims.

My present invention relates to current magnitude ratio-responsive electron discharge devices, and more especially to amplifier circuits which are responsive solely to current magnitude ratios.

It has been known in the past to provide a response according to the ratio of the magnitudes of two currents but the only device available, of Y which I am aware, has been a current ratio metering instrument in which a magnet bearing a needle is mounted inside two crossed magnetizing coils. In this case the magnet aligns itself parallel to the magnetic field set up by currents owing through the coils. The needle indicates on a suitable scale the ratio of the currents. However, it has not been known howto secure an electronic current magnitude ratio-responsive device.

One of the main objects of my present invention is to provide a method of controlling the division of a current into two parts according to the ratio of the magnitudes of two control currents,

I have found that when a magnetic field in a vacuum is made strong enough substantial electron motions can take place only in the direction parallel to the magnetic field. Any component of motion in other directions is overcome, because the magnetic field bends the path of motion in these directions back to the axis from which they started. Having confined the motion of electrons to directions parallel to a magnetic field, this direction may be controlled by varying the direction of the eld.

Accordingly, it may be stated that it is an important object of this invention to provide a pair of crossed magnetizing coils within which is located a cathode and an arrangement of anodes, the distribution of electron current to the anodes being controlled by controlling the direction of the magnetic field, and the latter in turn being controlled by the ratio of the magnitudes of the currents in the two coils independently of the individual amplitude of these currents.

In the reception of frequency or phase modulated carrier wave energy, and which generically may be referred to as angular velocity-modulated carrier wave energy, it has been the practice in the past to utilize an amplitude modulation limiter prior to the frequency modulation detector. The purpose of the amplitude limiter has been to minimize the effect of noises, undesirable impulses external to the receiver and other well known effects.

Another important object of this invention is to provide a method of receiving angular velocity-modulated carrier wave energy wherein amplitude limitation prior to the detector is not employed, but in place thereof, and subsequent to the detection of the wave energy, there is provided an audio frequency output which, over a large range of amplitudes, is substantially independent of the amplitude of the radio frequency input energy to the receiving system.

Still other objects of my invention are to improve generally the operation of frequency modulation receivers, and more especially to provide current magnitude ratio-controlled electron discharge devices which are reliable and eicient, as well as economical to construct.

The novel features which I believe to be characteristic of my invention are set forth with 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 several circuit organizations whereby my invention may be carried into effect.

In the drawings:

Fig. l shows a schematic diagram of a frequency modulation receiver embodying one form of my invention,

Fig. 2 shows in lateral section a modication of the current ratio-controlled amplifier,

Fig. 3 is a longitudinal section through the amplifier of Fig. 2,

Fig. 4 shows another form of current ratiocontrolled electron discharge device,

Fig. 5 is a section on line 5-5 of Fig. 4 looking in the direction of the arrows,

Fig. 6 shows one form of anode configuration useful in the device of Fig. 4,

Fig. 7 is the anode current response characteristic for the anodes of Fig. 6,

Fig. 8 shows a modified form of anode configuration,

Fig. 9 is the anode current characteristic for the anodes of Fig. 8.

Referring, now, to the system of Fig. 1, there is shown an electron discharge device which I have designated as a current magnitude ratiocontrolled amplier. The device generally comprises an evacuated glass envelope l which has a relatively constricted portion housing an electron emission element, or cathode, 2. The flared portion of envelope I houses at the broad end thereof a pair of spaced hollow collector electrQQlSS 3 and 4. Between these electrodes is posi- 3 tioned an electrode 5. The electrodes 6, 'I and 8 are spaced in succession along the electron stream 9 to cause the stream to act as a beam, and to focus the beam normally upon the electrode 5. The potentiometer P supplies direct current voltages to the various electrodes. Thus, electrodes 3 and 4 are connected to opposite ends of theprimary winding of .transformer I0. The midpoint of the primary winding is connected to the positive terminal of the potentiometer P.

Electrode 5 is connected to a less positive point on P, while electrodes Il, 'I and are connected to points of successively less positive potential. Cathode 2 is connected to the negative termi-nal.

Any desired form of heater element `may be used for the cathode. The device described thus far comprehends the elements within the tube envelope. A pair of crossed annular coils II and I2 are provided at a point of the envelope such that a magnetic control field is set up which will control the electron beam 9. The coils I I and AI2 are supplied with the currents whose lmagnitude Yratio is 'to be indicated at the output Ill.

The tilted coils II and I2 produce a magnetic field whose direction depends on the ratio of the magnitudes of currents. liowing through the coils, but not ron their individual amplitudes. The electron `stream 9 can flow only in the direction of the field, if the latter is strong enough. 'The energizing currents flowing through coils I I and I2 may be derived from any ,desired sources of high frequency current whose ratio is to be determined. By way of illustration, and as one object of my invention, the current sources are shown as consisting of a pair of separate discriminator-recti- 1 fier networks I3 and Ill.

The networks I3 and I4 may correspond to the back to back detectors for frequency modulated (FM) carrier waves which are well known in the art. These networks may be tuned to the operating intermediate frequency (I. F.) Value where the receiver is of the superheterodyne type. The circuits of such a'receiver are too well known to lrequire detailed description. In the case of a frequency modulation receiver of the superheterodyne type, there may be applied, for example, signals whose mean frequency lies in a range of 42-50 megacycles (mc), the presently assigned FlVI band. The frequency deviation i-s over a permissible range of 150 kilocycles (ka). However, the selector circuits are made wider so that the entire modulation-representative deviations will be applied to the discriminator networks thereby reducing distortion and the effects of noise. For

example, at the discriminator the pass band width can be 200 kc.

The discriminator-rectifier networks I3 and I4 may be of the type wherein network I3 is a rectier having a resonant input circuit olf-tuned to one side of the center, or mean, frequency in excess of 75 kc., while network I4 may be a second rectifier whose resonant input circuit is olf-tuned to the opposite side of the center frequency in excess of 75 kc. Thus, as the FM signal energy from the I. F. amplifier (which may be tuned to an I. F. chosen from 3 to 15 mc.) is applied to the off-tuned circuits, there will be produced in the rectier output circuits the modulation currents corresponding to the frequency deviations of the carrier. The outputs of the rectiers consist of two currents, the ratio of whose amplitudes is varied in response to frequency variation of carrier. In place of the off-tuned discriminator there may be used a discriminator of the type shown by S. W. Seeley in his U. S... Patent N9.

2,121,103, granted June 21, 1938. This type USGS a center-tuned resonant circuit to produce two alternating currents which vary differentially as the frequency is varied.

If no amplitude modulation were present in the FM waves, the output of networks I3 and I4 could be combined by means of a' transformer to provide a single output containing lmodulation frequency currents corresponding to the frequenlcy deviations. However, if amplitude modulation exists on the carrier wave, and which modulation may be Ydue to noise and other extraneous impulses, the amplitude modulation will also appear in the transformer output to a greater or lesser extent depending upon how far the carrier frequency has been deviated from the condition of equal output currents from the two detectors.

In the past it has been proposed to overcome this interfering output, due to amplitude modulation, by inserting some form of amplitude limiter ahead of the discriminator. In my present invention I overcome `the difficulty by eliminating a special limiter aheadof the discriminatori, and using instead the presently-disclosed current magnitude ratio-controlled amplifier. The output of the latter depends upon the ratio, and variations in ratio, of the magnitudes 0f two input currents, and not `upon their individual amplitudes. The cathode ray tube shown in Fig. l is purely illustrative. It -is somewhat like the devices shown in my .following patents: U. S. Patent No. 1,850,104; U. S. Patent No. 1,938,331; U. S. Patent No. 1,986,632; U. S. Patent No. 1,988,621; U. S. Patent No. 2,066,037; U. S, Patent No. 2,202,376; U. S. Patent No. 2,138,162; U. S. Patent No. 2,247,234.

However, in the present device the electron stream is magnetically deflected by means of 'a magnetic field strong enough vto constrain the motion of the electron stream substantially parallel to the magnetic field. It is more or less known in the art that electrons can be given a substantial movement only in directions parallel to the magnetic field when the latter is strong enough. This is the phenomenon used in connection with magnetic focussing of electron beams. By passing the output currents of networks I3 and I4 through a pair of respective crossed magnetizing coils II and I2, there may be produced `a magnetic field whose direction is dependent completely upon the magnitude ratio of currents flowingthrough the two coils. If this magnetic eld is strong enough in proportion to the kinetic energy of the moving electrons, the electron stream must take a direction substantially parallel to the field. Hence, modulations in the ratio of the two currents control almost completely the distribution of electron current between the output anodes. Since the electron current is constant and its distribution between the anodes depends only upon the ratio 0f the magnitudes of the currents in the coils, and not on the individual amplitudes of these currents, the device functions to eliminate substantially all effects of amplitude modulation of the received carrier energy.

By changing the magnitude ratio of the currents flowing through coils II and l2 the beam 9 can be moved from the predominantly central position on electrode 5 to either collector 3 or e. The electrode 5 is intended to reduce flow of wasteful currents between the anodes, due to secondary emission, when the anodes have a substantial difference in potential. The cup shape of the anodes has the same purpose of sponse characteristics.

`of the coils.

Asuppressing secondary emission by lcausing elec- `trons to strike in the cups where there is little electric field for drawing out secondary electrons. The secondary emission can cause wasteful loading of the output circuits and distortion in re- If the coil currents change by equal ratios, there occurs substantially no movement of the beam. The collectors 3 and 4 catch the electron stream when displaced from the normal position. The division of current between the collectors is controllable by the ratio of currents in the two magnetized coils substantially independently of the sum of the currents The device provides, therefore, one means by which there can be provided an FM receiver having an output substantially independ- -e'nt'of the received carrierr amplitude, and having an output substantially free from output derived from amplitude modulation ci the carrier current and without using an amplitude limiter.

It is possible to change the construction of the current magnitude ratio-responsive device considerably, and yet secure the same result. For example, in Fig. 2 there is showny a lateral section through an electron discharge device whose longitudinal section is depicted in Fig. 3. Description of this modication will be given by concurrent reference to both gures. The tube comprises a cylindrical evacuated envelope 2Q which is provided with an axial filamentary cathode 2l. A positively biased screen 22 surrounds the cathode; the potentiometer P again provides the direct current potentials for the various tube electrodes. The numeral 23 designates four anodes in the shape of four segments of a cylinder surrounding screen 22. An absorption electrode 24. in the form of a cylinder concentric with the segmental anodes 23, surrounds the latter.

The tube is disposed within two crossed magnetizing coils 30 and 3i. The coils are represented in cross-section, and the wires thereof are schematically represented. The coils 3l! and 3| set up a magnetic iield at right angles to the direction of the axis of the device.` The coils pro- Vduce magnetic elds in directions parallel to the plane of the paper. The electron currents flow in similar directions, parallel to the eld. The direction of this field with respect to the dispo sition of the anodes 23 is controllable by controlling the magnitude ratio of currents in the two coils. If the two coils carry equal currents, electrons are able to flow only in up and down directions as Fig. 2 is viewed. However, if the magnitude ratio of currents is varied so as to result in a variation in the direction of the magnetic eld, the current to one pair of diametrically opposite anodes will be increased, while the current to the diametrically opposite anodes is decreased. Accordingly, diametrically opposite anodes 23 are electrically connected together, and each pair of anodes is connected to a respective end of the primary winding of transformer lo.

Since the midpoint of the primary Winding of audio transformer Il! is connected to the positive terminal of potentiometer P, it will be seen that spective dlscrlminator-rectiiier networks I3 and I4, as shown in Fig. 1. Accordingly, as the frequency of the received carrier current is modulated, the distribution of currents between the pairs of anodes 23 is modulated to provide an audio frequency output which is substantially independent of the amplitude of radio frequency input to the FM detector system.

In the arrangement shown the screen electrode 22 makes it possible to have the electrons travel over the greater part of their path from cathode 2| to anodes 23 at relatively low velocity. Accordingly, only moderate magnetic eld strength is required to control the direction of electron flow. The anodes are operated at much higher potential than the screen electrode in order that it may be possible to derive large amounts of power from the device. The arrangement shown in Fig. 2 may be given an improved operating characteristic if there is provided a means to hold constant total current to coils 3i! and 3l. For example, reference is made to my cor-pending patent application Serial No. 423,881, led December 22, 1941, for a suitable means for maintaining a constant current to the magnetizing coils. The advantage of constant total current to the two coils is that there is eliminated minor variations in response characteristics of the device due to variations in concentration of the electron stream which could be brought about from variations in the total strength of the magnetic field.

In Figs. 4 and 5 I have shown a further modiiication of a current magnitude ratiocontrolled device in which the distribution of electron currents between tWo sets of anodes is controlled by means of the direction of the magnetic field. The direction is, in turn, controlled by the magnitude ratio of currents in the crossed control coils. In the modication of Figs. 4 and 5 the crossed magnetizing coils are not shown, because it can readily be seen from Fig. 2 that the modication of Fig. 5 differs solely in the arrangement of the electrodes. In general, the tube structure is similar to that of the modification of Fig. 2.

Referring, then, to Fig, 4 the glass envelope d0 is substantially a hollow cylinder, and has located at the axis thereof an indirectly heated cathode which is surrounded by a screen grid 6|. The supporting rods 42 of the screen grid are shown in Fig. 5. The four segmental anodes surround the screen grid. Catcher electrodes 43 and 44 are shown in spaced relation. One of the catcher electrodes is symmetrically located behind the upper pair of anodes, while the second catcher electrode is symmetrically located behind the lower pair of anodes. The anodes are connected in the same way as in Fig. 2. It is assumed that a magnetic iield passes through the tube which is directionally controllable around a direction up and down as viewed in Fig. 5. This, of course, presupposes a pair of coils arranged as coils 35i and 3| in Fig. 2. With this type of tube, as the direction of the eld is varied the distribution of currents between adjacent anodes and the catcher electrodes is varied.

The law of response of anode currents to magnetic i'leld direction is controllable by controlling the design, or configuration, of the anode segments. Suppose, for example, that one wishes to obtain anode currents corresponding to the currents contained in a class B amplier. Then, the gap 46 between adjacent ends of anodes, where the electron stream impinges, may be shaped as shown in Fig. 6. In Fig. 6 the eiectron stream is assumed to be normal to the plane of the sheet of the drawing. In Figs. 4 and 5 the gap between adjacent anodes is suggested, but

' is more clearly shown in Fig. 6. It will be noted that the gap is substantially V-shaped. Such assise@ 7 Va gap l'results in a response characteristic simi.- lar to that represented in Fig. 7.

If, now, it isdesired to secure -a .response characteristic corresponding to 'a class A amplifier, then the `gap between adjacent edges of anodes may be made substantially as shown in Fig. 8. In this case `the gap is Yan inclined slit `whose vlopposed edges are parallel. VThe resulting response characteristic is shown lin Fig. 9. To see Why the electrode conflgurationsof Figs. 6 and .8 .give the indicated response characteristics consider that the electron beam, enclosed by the kdotted lines, moves from right 'to left in response to change in direction voi the vmagnetic `field, and that the flow'of current to each electrode is pro- ;portional to the area ofthe portion of the beam .falling on it. By using various other shapes and coniigurations dimensions, andthe like, of the gap lbetween adjacent ends of anodes, one may `,obtain substantially any type of response charvacteristic desired. The type of tube shown in Figs. 4 and 5 provides a most practical arrangement for obtaining any law of response with respect to input control which may be desired. The structure is simple and rugged, and .the Vsensitivity should be considerable if the device is designed to operate with relatively low potential vbetween. the cathode and grid electrode in which most of the electron stream deflection ltakes place. The anodes i5 may -t-hen be operated et any higher Vpotential for obtaining relatively high power output. The .electron eiciency of the device can be made quite high by so design- ,ing the cathode and screen vthat substantially all -oi the yemission from the cathode is drawn out Vand forced to follow a path more or less parallel to lthe magnetic eld.

It will be understood that the catcher -elec trodes i3 and M of Figp5 are connected together vand connected to a moderate potential source which is less than the anode potential source. In practice, the ycatcher electrode potential vwould usually be as low as possible, perhaps 25 or 30 volts, so as to minimize secondary emission curvrents from the catcher back to the anodes,

By simply physically turning the tube about its axis, within .fixed field coils, one may dinerentially bias the tube Ain one direction or the other, Las desired. Thus, if the tube .is used in indicating current magnitude ratios, or as a ratio `Lcontrol device, one -may change the ratios at will b-y Ephysically .rotating the tube Within the mag- .netizing field coil. Of course, if'desired, the tube .may .be left-stationary, and the magnetizing coils may be .rotated around .the axis of the tube.

While I have indicated and described several 4systems for carrying my invention into eect, it will be apparent to one skilled in the art that my invention is by no means limited to the particular organizations shown and described, but that many modications may be made without departing from the scope of my invention, as set forth inthe appended claims.

What I claim :is:

1. The method of indicating the ratio of mag- ;nitudes of two separate currents which -includes :the steps of initiating a flow of charged particles, subjecting said charged particles over a substan- ...tial portion of its path of travel to a eld whose .influence forces the charged particles to flow.

,isubstantially only along the aXis of :the stream,

utilizing one of said currents to control one com- '.IQnent of `said i'leld, concurrently utilizing said @ther .current to control another component of Vsaid eld having an angular relationtosaid lirst .component whereby the direction of s aid field is dependent upon said ratio and thepreponder- `ance of one component over the other producesa transverse deflection of said charged particles.

2. The method of indicating the ratio of lmagnitudes of two separate currents which includes the steps of initiating a flow of charged particles, subjecting said charged particles over a substantial portion of its path of travel to a eld whose n influence forces the charged particles to flow substantially only along the axis of the stream, utilizing one of said currents to control one 4compo,-

Vnent of-said field, concurrently utilizing said other current kto control another .component'of said field having an angular relation to said ,rst compo.- nent whereby the direction of said field is jdependent upon said ratio and the preponderance of vone component over the other produces `a trans- :verse deflection of said charged particles, andcollecting said charged particles 0n spaced electrodes distributed in response vto said deiiection.

3. The method of Vindicating theratio ,of magnitudes of two separate currents which includes fthe .steps of initiating a'flow of charged particlessubjecting said charged particles over a substantial portion of its path of travel toa magnetic eld whose inuence forces the charged particles to now substantially only ,along the `axis of fthe stream, utilizing one of said currents to control one component of said 7iield, concurrently utilizing Said other current to control vanother component of said field having an angular relation vto Said rst component whereby the direction ofsai'd eld is dependent upon said 4ratio and the .preponderance of one component over `the other produces a transverse deflection of said charged par.- ticles.

4. A method of securing a -response to the ratio between the magnitudes of at least vtwo alternating currents which includes the steps of providing an electron stream to a pair of output electrodes,

distribution of electron current to fthe electrodes by controlling the direction vof the 'field in 1response to solely said ratio.

5. In an electronic system, a tube having at least an electron emitter, at least two spaced anodes, said emitter-.projecting an electron stream toward the anodes, means providing a magnetic field whose influence forces electron current -to flow only in a direction parallel to the eld `and to a point between the spaced anodes, and addi tional means for applying to said magnetic field means at least -two alternating currents whose magnitude lratio is solely utilized to deflect said stream.

6. The method of determining the ratioof magnitudes of two audio currents subject to amplitude variation which includes .the steps of initiating a flow of charged particles, subjecting said charged particles over Va-substantial portion .of its path of travel to a magnetic eld of sulicient strength to substantially suppresscomponents ,of

flow at right angles to the direction vof the field,

utilizing one of said audio currents to control one 'solely said :ratio free of said amplitude variation.

7. The method of producing a response to the ratio of magnitudes of two alternating currents subject to amplitude variation which includes the steps of projecting a now of charged particles. subjecting said charged particles over a substantial portion of its path of travel to a magnetic field strong enough to confine the fiow substantially to a direction parallel with the field, utilizing One of said currents to control one component of said field, concurrently utilizing said other current to control another component of said field having an angular relation to said first component whereby the direction of said field is determined solely by said ratio and the preponderance of one component over the other produces a transverse deflection of the direction of iow of said charged particles.

8. In a system Vfor indicating the ratio of magnitudes of two separate currents which comprises means for initiating a iiow of charged particles, means for subjecting said charged particles over a substantial portion of its path of travel to a field which permits substantial flow only in a direction parallel to the field, means utilizing one of said currents to control one component of said field, means concurrently utilizing said other current to control another component of said field having an angular relation to said first component, and the preponderance of one component over the other producing a transverse deflection of said charged particles.

9. In a system for determining the ratio of magnitudes of two audio currents subject to amplitude variation which includes an electronic device having a means for initiating a ow of charged particles, a pair of magnetizing coils whose planes are crossed subjecting said charged particles over a substantial portion of its path of travel to a magnetic field in response to the currents to form a resultant field whose direction depends upon the ratio of the two currents, and utilizing the resultant field to control the direction of flow of charged particles substantially independently of field for determining the direction of flow, means applying one of said audio currents to one coil thereby to control one component of said field, means applying the second current to the second coil thereby to control another component of said field having an angular relation to said first component, the preponderance of one component over the other produces a transverse deflection of said charged particles.

10. A method of indicating the ratio between the magnitudes of at least two audio frequency currents subject to amplitude variation which includes the steps of providing an electron stream to a pair of electron collectors, providing a magnetic field whereby substantial electron current flow can take place only in the direction parallel to the magnetic field and to a point between said collectors, and controlling the distribution of electron current to the collectors by controlling the direction of the field in responseto solely said magnitude ratio of said currents.

11. A system for indicating the ratio between the intensity of at least two currents, which comprises an electron discharge device having a cathode, a pair of spaced anodes, crossed magnetizing coils surrounding the device propagating an electron stream from the cathode to a point intermediate the anodes, said coils normally providing a magnetic field for controlling the direction of iiow of th'e stream, and means applying said currents separately to said respective coils thereby to control the direction of the field and the intensity of electron current collected by either anode as a function solely of said ratio.

12. The method of indicating the ratio of magnitudes of two separate currents which includes producing two angularly disposed components of the sum of the two currents.V

13. The method of indicating the ratio of magnitudes of two separate currents which comprises utilizing the currents to produce a resultant magnetic eld the direction of which is dependent only on the ratio of magnitudes of the two currents, and utilizing the resultant magnetic field to determine the direction of flow of electron current in a Vacuum tube.

14. The method of utilizing the ratio of magnitudes of two separate currents substantially independently of their individual magnitudes which comprises utilizing the currents to produce a magnetic field the direction of which is dependent only on the ratio of the magnitudes of the currents, and utilizing the direction of the field to control distribution of electron current between electrodes in a vacuum tube.

l5. Means responsive to the ratio of the magnitudes of two currents comprising magnetizing coils crossed over atan angle for producing a resultant magnetic field, means for producing a constant current electron stream, and means for collecting currents from the stream whose sum is constant but whose division is determined by the direction of the magnetic field.

16. In a system for obtaining currents responsive to the magnitude ratio but not the separate amplitudes of two currents comprising means to set up a magnetic field whose direction is determined by the ratio, and means to utilize the direction of the magnetic field to determine the distribution of electron current between electrodes of a vacuum tube.

17. In a system as defined in claim 16, characterized by adjustment of the strength of magnetic field to be great enough so that, over an operating range of field strengths, the distribution of electron current is nearly independent of the strength of the field.

18. The method of receiving angular-velocity modulated carrier waves subject to amplitude variation which includes deriving from the waves two separate modulation currents subject to said variation, initiating a flow of charged particles, subjecting said charged particles over a substantial portion of its path o-f travel to a field Whose influence forces the charged particles to fiow substantially only along the axis of the stream, utilizing one of said modulation currents to control one component of said field, utilizing said other modulation current to control another component of said field having an angular relation to said first component whereby4 the preponderance of one component over the other produces a transverse deflection of said charged particles, and translating said denection into a resultant modulation current free of said variation.

19. The method of receiving frequency modulated carrier waves subject to undesired amplitude variation, which includes deriving from said waves two audio currents subject to said undesired variation, initiating a flow of charged particles, subjecting said charged particles over a sub- 0 stantial portion of its path of travel to a magnetic eld of sufficient strength to substantially suppress components of now at right angles to the direction of the field, utilizing one of said audio currents to control one component of said field,

utilizing said other audio current to control angction into a. resultant ludi' current fre of said.v

ilaria lon in satijd c' dshrgv device spaced nod'es, c'r rounding the de y I n strm from the' c odejto latvpoit intermediate' the anodes, said coils riorrnaHyproviding' a mgf netic eid for c0n .t rc 1 linfg` the direction Qi flow/off the stream', arid `nflirrs ,applying Said modulation currents Separately to s'aid respective coils tlfierejf by to contro-11th@ directi'nfof tiigriield a-djtlje intensity of electron current collected by eitl'rf anode.

CLARENCE W. HANsELI-i;

REFERENGES 'ci-TED The following Yfei'r'eric'es e' f rcord. r tiY le of this patent: K

UNITD STATES PATENTS- Nine Y bate L Skeuet' o'ct. 15, 194g Wagner' Nv. I2, 1940 uirier Y 2,217,774 25v 2,221,743

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