US1547154A - Amplifying apparatus - Google Patents

Description

July 21, 1925. 1,547,154 A. w. HULL AMPLIFYING APPARATUS Filed Aug. 15, 1924 inventor: Albert, w. Hull His Abborn ey.

ing currents.

Patented July 21, 1925.

UNITED STATES PATENT FFIE.

ALBERT W. HULL, 0F SGHENECTADY, NEW YORK, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

AMPLIFYING APPARATUS.

Application filed August l5, 1924. Serial No. 732,284.

To all whom it may concern:

Be it known that I, ALBERT 1V. HULL, a citizen of the United States, residing at Schenectady, in the county of Schenectady, State of New York, have invented certain new and useful Improvements in Amplifying Apparatus, of which the following is a specification.

My present invention relates to electron discharge apparatus and circuits" for amphfying and detecting high frequency s1gnal- One of the objects of my invention is to provide a circuit arrangement whereby the amount of amplification which may be obtained with a single device maybe greatly increased. 5

It has been proposed in the past to em ploy a three electrode electron discharge device for the simultaneous amplification of radio frequency currents and audio frequency currents. So far as I am aware however no one has heretofore proposed any practical system whereby a four electrode electron discharge device, particularly one i of the negative resistance or pliodynatron type, could be employed for the simultaneous amplification of both radio and audio frequency currents.

Aqnore specific object of my invention is to provide a circuit arrangement whereby a pliodynatron may be successfullyemployed to serve the two functions-mentioned.

The novel features which I believe to be characteristic of my invention are set forth with particularity in the appended claims,

My invention itself, however, both as to its organizationand method of operation will best be understood by reference to the following descriptiontaken in connection with the accompanying drawing in which Fig. 1 shows diagrammatically one form of my invention and Fig. 2 shows a modification thereof. p

1 have indicated in the drawing an electron discharge device 1 having the usual electron emitting cathode 2, plate electrode 3'and two grids 4 and 5 interposed between cathode and plate. The grid 4 serves as a control grid and the grid 5 serves as an anode for receiving impact electrons emitted from the plate 3. A source of potential 6 which is connected in the circuits between I the cathode 2 and plate 3 and grid 5 furnis'hes suitable values of potential for ap plication to electrodes 3 and 5 to produce a of grid electrode 5.

negative resistance in the plate circuit by reason of the emission of impact electrons from the plate 3. By suitable adjustments the negative resistance produced in this way may be. made great enough to compensate for the losses of the system without at the same time causing the production of oscillations.

In the system shown in Fig. 1, the plate circuit may be tuned to the frequency of the high frequency oscillations to be amplified by means of inductance 7 and variable conof high frequency signaling currents re ceived upon an antenna 12 and supplied by a coupling transformer13 to the tuned input circuit 14 of device 1. Received radio frequency currents are amplified by device '1, rectified by crystal detector 9 and the audio frequency currents produced by rectification supplied to the input circuit by transformer 10, 11 and also amplified. An indication of the amplified audio frequency currents maybe obtained in the usual telephone receiver 15 connected 'in the circuit By- pass condensers 16 and 17 are preferably provided for bypassingaround the transformer 10, 11 the radio ,frequency components of the currents flowing in the circuit of the crystaldetector and the input circuit respectively.

In the modification of my invention, shown in Fig. 2, the detector circuit instead of being conductively connected to the plate circuit-is coupled thereto by means of a condenser 18. The rectifier circuit instead of being inductively coupled to the input circuit is coupled thereto by a resistance coupling, the audio frequency currents produced by rectification being caused to flow through a resistance 19 which is included in the input circuit. most satisfactory operation of the system describedmay be obtained with crystal detectors whichpperate best when slightly polarized. In the arrangement shown in Fig.

2, the adjustable contact 20 on potentiometer I have found'that the,

21 which is connected to battery 22 furnishes the desired polarizing potential to the crystal detector 9 through a choking inductance 23. The potential applied to the input circuit in this way also serves as a biasing potential for the control grid 4%. In Fig. 2, I have indicated the inductance 7 and condenser 8 as both variable and these are preferably so arranged that tuning of the plate circuit is accomplished by simultaneous adjustment of both, as by this expedient the power factor of the plate circuit may be maintained substantially constant over a wide range of frequencies, If desired filters 24.- and 25 may be provided at the points indicated to prevent high frequency currents from flowing in the circuits in which they are connected.

While I have shown and described only two modifications of my invention, it will be apparent that many modifications in the particular apparatus employed and in the manner in which it is connected in the circuit may be made without departing from the scope of my invention as set forth in the appended claims. I

What I claim as new and desire to secure by Letters Patent of the United States is 1. The combination in an amplifying system of an electron discharge device having an electron emitting cathode, a plate electrode and two grid electrodesinterposed between cathode and plate, circuit connections between the cathode and each of the other electrodes, means for impressing high frequency currents to be amplified upon the circuit between the cathode and one of said grids, sources of potential connected in the circuits between the cathode and the plate and second grid of such value that a negative resistance is produced in the plate circuit of high enough value to compensate for the losses of the system, means for tuning the plate circuit to the frequency of the high frequency currents, means for rectifying the amplified high frequency currents produced in the plate circuit, means for supplying low frequency currents produced by such rectification to the first grid circuit and means for producing an indication of the amplified low frequency currents in the circuit of the second grid.

2. The combination in an amplifying system of an electron discharge device having an electron emitting cathode, a plate elec-' trode and two grid electrodes interposed between cathode and plate, circuit connections between the cathode and each of the other electrodes, means for impressing high frequency currents to be amplified upon the circuit between the cathode and one'of said grids, sources of potential connected in the circuits between the cathode and the plate and second grid of such value that a negative resistance is produced in the plate circuit of high enough value to compensate for the losses of the system, means for tuning the plate circuit to the frequency of the high frequency currents, a crystal detector connected in a circuit which is coupled to the tuned plate circuit, a coupling between the circuit of the crystal detector andthe circuit of the first grid and means for indicating the resultant currents produced in circuits between the cathode and the plate and second grid of such value that a negative resistance is produced in the plate circuit of high enough value to compensate for the losses of the system, means for tuning the plate circuit to the frequency of the high frequency: currents, a crystal detector connected in a circuit which is coupled to the tuned plate circuit, a coupling between the circuit of the crystal detector and the circuit of the first grid, means for indicating the resultant currents produced in the circuit of the second grid, and a common means for supplying a polarizing potential to the crystal detector and a biasing potential to the first grid.

4:. The combination in an amplifying system of an electron discharge device having an electron emitting cathode, a plate electrode and two grid electrodes interposed between cathode and plate, circuit connections between the cathode and each of the other electrodes, means for impressing high frequency currents to be amplified upon the circuit between the cathode and one of said grids, sources of potential connected in the circuits between the cathode and the plate and second grid of such value that a negative resistance is produced in the plate circuit of high enough value to compensate for the losses of the system, a variable inductance element and a variable capacity element connected in parallel in the plate circuit, a single means for simultaneously adjusting both of said elements to tune the plate circuit to the frequency of the high frequency currents means for rectifying the amplified high frequency currents produced in the plate circuit, means for supplying low frequency currents produced by such rectification to the first grid circuit and means for producing an indication of the amplified low frequency currents in the circuit of the second grid. 7

5; The combination in an amplifying system of an electron discharge device having an electron emitting cathode, a plate elec- .trode and two grid electrodes interposed begrids, sources of potential connected in the .cating the resultant currents circuits between the cathode and the plate and second grid, means for tuning the plate circuit to the frequency of the high frequency currents, means for rectifying the amplified high frequency currents produced in the plate circuit, means for supplying low frequency currents produced by such rectification to the first grid circuit and means for producing an indication of the amplified low frequency currents in the circuit of the second grid.

6. The combination in anamplifying system of an electron discharge device having an electron emitting cathode, a plate electrode and two grid electrodes interposed be-t tween cathode and plate, circuit connections between the cathode and each of the other electrodes, means for impressing high frequency currents to-be amplified upon the circuit between the cathode and one of said grids, sources of potential connected in the circuits between the cathode and the plate and second grid,"means for tuning the plate circuit to the frequency of the high frequency currents, a crystal detector connected in a circuit which is coupled to the tuned plate circuit, a conductive coupling between the circuit of the crystal detectorand the circuit of the first grid and'means for indiproduced in the circuit of the second grid. 7. The combination in an amplifying system of an electron discharge device having an electron emitting cathode, a plate elecmy hand this 14th trode and two grid electrodes interposed between cathode and plate, circuit connections between the cathode and each of the other electrodes, means for impressing high frequency currents to be amplified upon the circuit between the cathode and one of said grids, sources of potential connected in the circuits between the cathode and the plate and second grid, means for tuning the plate plate circuit, a conductive coupling betweenthe circuit of the crystal detector and the circuit of the first grid, means for indicating the resultant currents produced in the circuit of the second grid, and a common means for supplying a polarizing potential to the crystal detector and a biasing potential to the first grid.

8. The combination in an amplifying system of an electron discharge device having an electron emitting cathode, a plate electrode and two grid electrodes interposed between cathode and plate, circuit connections between the cathode and each of the other electrodes, means for impressing high fre; quency currents to be amplified upon the circuit between the cathode and one of said grids, sources of potentialconnected in the circuit of the first grid and means'for indicating the resultant currents produced in the circuit of the second grid.

In witness whereof, I have hereunto set day of August, 1924.

ALBERT W. HULL.

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