US1547152A - Amplifying apparatus - Google Patents

Description

July 21, 1925.

F. R. ELDER AMPLIFYING APPARATUS Filed Sept. 27, 1924 l w/enter: Frank R.E.lde'r-',

9 M His Attornev cathode and plate.

Patented July 21, '1925.

UNITED STATES 1,547,152 PATENT OFFICE.

FRANK R. ELDER, OF SCHENECTADY, NEW YORK, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

AMPLIFYING ArrARA'rus.

Application filed September 27, 1924. Serial No. 740,894.

To all whom it may concern:

Be it known that I, FRANK R. EnDER, a citizen of the United States, residing at Schenectady, in the county of Schenectady, State of New York, have invented certaln new and useful Improvements in Ampl fying Apparatus, of which the following is a specification.

My present invention relates to electron discharge apparatus and circults for amplifying anddetecting high frequency signaling currents. One of the ob ects of my invention is to provide a circuit arrangement whereby the amount of amplification WllICll may be obtained with a single device may be greatly increased.

It has been proposed in the past to em ploy a three-electrode electron discharge device for the simultaneous amplificatlon of radio frequency currents and audio frequency currents. Another object of my 1nvention is to provide a practical system whereby a four-electrode electron discharge device, particularly one of the negative resistance of pliodynatron type, may be employed for the simultaneous amplification of both radio and audio frequency currents.

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 ts organization and method of operatlon Wlll best be understood by reference to the following description taken in connection with the accompanying drawing in which Flg 1 shows diagrammatically one form of my 1nvention, and Fig. 2 shows a modification thereof.

I 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 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 potential6, which is connected in the circuits between the cathode 2 and plate 3 and grid 5 furnishes suitable values of potential for application to electrodes 3 and 5 to produce a negative resistance in the plate circuit by reason of the emission of impact electrons from the plate 3. The potential applied to the plate 3 may be adjusted by means of the sliding contact on resistance 7, which is connected in shunt to source 6. By suitable adjustments the negative resistance produced in this Way may be made great enough to compensate for the losses of the system, and at the same time cause the production of oscillations, if desired.

In the system shown in Fig. 1, the plate circuit may be tuned by means of inductance 8 and variable condenser 9 to the frequency of the high frequency oscillations to be amplified in case modulated waves are to be received, or to a slightly different frequency if unmodulated waves are to be received. By suitable adjustment this amplification of the high frequency currents may be made asymmetric so that the resulting current in the plate circuit will be capable of operating a signal indicator. The low frequency component of the current thus produced in the plate circuit is fed through the primary 10 of a transformer, the secondary 11 of which is included in a link circuit with the primary 12 of a second transformer having a secondary 13 included in the input circuit connected between cathode 2 and'control grid 4.

I have indicated the application of my invention to the amplification and detection of high frequency slgnaling currents received upon an antenna 14 and supplied by a coupling transformer 15 to the tuned input circuit 16 of device 1. Received radio frequency currents are amplified by device 1, and the audio frequency currents produced in the .plate circuit are supplied by transformers 1011, 12-43, to the input circuit and also amplified. An indication of the amplified audio frequency currents may be obtained in the usual telephone receiver 17 connected in the circuit of grid electrode 5. By- pass condensers 18, 19, 21 and 22 are preferably provided for by-passing around the transformer- windings 10 and 13 and resistance 7, the radio frequency components of the currents flowing in the plate circuit and the input circuit.

In the operation of the system described, the adjustment should be such that the damping of the high frequency oscillating circuit is low and the damping of the low frequency circuit is high; in other words, the transformer in the plate circuit should be incapable of causing audio frequency oscillations by reason of its inductance and distributed capacity. A resistance 20 inserted in the link circuit between the plate circuit and the input circuit will increase the damping and thus prevent oscillations.

In the arrangement shown in Fig. 2, the link circuit is omitted, the secondary 11 being connected directly in the input circuit. In this case, the tendency of the plate circuit to oscillate at the audio frequency may be prevented by a series resistance 23 in the plate circuit.

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 1n the manner in which it is connected inthe circuit may be made without departing from the scope of my invention as set forth in the ap ended claims.

Vhat 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 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 a desired high frequency, means for producing low frequency currents in the plate circuit and supplying them 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 sys' tem 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, means for tuning the plate circuit to a desired high frequency, a link circuit containing a resistance and which forms a coupling between the plate circuit and the circuit of the first grid, and means for indicating the resultant currents produced in the circuit of the second grid.

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, means for tuning the plate circuit to a desired high frequency, means for producing low frequency currents in the plate circuit, means for preventing audio frequency oscillations in the plate circuit, a coupling between the plate circuit and 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 my hand this 26th day of September, 1924.

FRANK R. ELDER.

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