US1584561A - Sending system - Google Patents

Description

May 11,1926. 1,584,561

L. KUHN I SENDING SYSTEM Filed Sept. .5 1921 Patented May 11, 1926,

UNITED STATES PATENT OFFICE.

LUDWIG xttrm, or cmarorrnuaune, um BERLIN, REPUBLIC or GERMANY, as

SIGNOR TO WESTINGHOUSE ELECTRIC AND MANUFACTURING COMPANY, OF EAST PITTSBURGH, PENNSYLVANIA, A CORPORATION OF PENNSYLVANIA.

. SENDING sysrnm,

Application filed September 3, 1921. Serial No. 498,566.

' (GRANTED UNDER THE PROVISIONS 01? THE ACT OF MARCH 3, 1921, 41 STAT. L, 1318.)

This invention relates to sending devices for either telegraphic or telephonic radio communication.

It is an object of this invention to avoid the disadvantages which'frequently accompany the regenerative action of transm tters in which the plate circuit is eleotrosta ically or electromagnetically coupled to the grid circuit. o

fIt'is a further object of this invention to provide for modifying the amplitude'of of the construction of the device will be apcontinuous high frequency oscillations in the grid circuit, without employing energy obtained from the plate circuit.

It is a further object of this invention to provide a tuned. circuit, resonant at high frequency, with a device by meansof which a low frequency modulation may be impressed thereon.

It is a further object of this invention to provide a modulating means which employs only a Very small amount of energy and is capable of producing large changes in the radiated energy. p

Other objects of my invention and details parent from the following description and the accompanying drawing in which:

Figure l is a diagram of circuits showing oneeform of my invention,

a modification of one shown in Fig. 1, Fig-1 is a like illustration of another m'odification of the same part, and

Fig. 2 isv a diagrammatic showing of circuits embodying another modification of my invention.

The vacuum tube device is provided with an anode 1 and a cathode 2. A battery 3 and a resistance 4 constituting the usual arrangement for supplying heating current to the filament or cathode 2.

, The plate circuit, which. connects the anode 1 and cathode 2, includes an inductance 6 by which it is coupled to the radiated circuit including an antenna 5 and the ground connection. The plate circuit is supplied with energy'by a battery 7 which is shunted by a condenser 8 in the usual way. The vacuum tube is supplied with a grid 9 which is connected to a circuit 10, tuned Fig. 1 is a diagrammatic illustration of part of the deviceinductive relation with the coil 12.-

Various means may be used for impress: ng low frequency potential changes upon the coil 13. One way of doing this is illustrated in Fig. 1, in which the terminals 14 and 15 of this coil are connected. through a battery 16 and a microphone 17.

When sound is received on the microphone, current fluctuations are developed in the circuit 1613 which causes a difference of potential between theterminals of this coil and this potential difierence is superposed upon the potential difference due to the high-frequency oscillations in the circuit 10, both high-frequency and low-frequency changes being impressed upon the grid 9. The energy of the high-frequency oscillations in the circuit 10 may, ifvdesired be relied upon to supply :the current through the microphone 17, and the battery 16 omitted.

The potential changes impressed upon the v grid 9 are amplified by the tube 1 and appear in the antenna circuit as modulated, highfrequency oscillations. Since there is no coupling between the grid circuit 14 and the plate circuit, no feed-backaction takes lace.-

It is not possible, therefore, for the tu e to obliterate the si ated by the tube itself. Since there is no tort the signal by too close a coupling. The

potential changes at the terminals of the.

coil 13, need not be produced by a microphone.- Any desired way of introduci an audio-frequency variation ma be su stituted. In Fig. 1 a buzzer is s own instead of the microphone. The'buzzer' is provided als by oscillations gener- 90 couplingto a'djust, it is not possible to dis,

' rent to pass readily.

generator is shown for impressingupon the coil 13,an audio frequency variation. Since the energy needed for this modulationis small, the alternating current generator may be driven by a small siren.

Instead of coil 13, a condenser may be used. This is illustrated in Fig. 2 in which the resonant circuit 10 is tuned by means of the inductance 12 and the adjustable condenser 11 and is energized from the coil 12 orin any other desired way. The condenser 20 is insertedinthe circuit 10 in a position corresponding to that of the coil 13. A second condenser 19 is shown between the grid 9 and the connected point of the circuit 10. Either of the condensers 19 and 20 may be omitted if desired. In order to provide an all-metallic path between the grid; 9 andthe cathode 2, the connection by means of which the audio-frequency energy is supplied is joined to the high-frequency circuit at the grid side of the condenser 19 and the cathode side of the condenserQO. In this connection, the secondary of a transformer 18 is included. The primary of this transformer is supplied with audio-frequency energy in any desired way; for example, by any of the'ineans described in connection with Fig. 1.

The condensers l9 and 20 are too small to pass audio-frequency current but are large enough to permit the radio-frequency cur- Consequently, ,the audio-frequency potential difference upon opposite sides of the condensers 19 and 20 is impressed upon the grid 9 without interfering with the action of the high-frequency circuit 10. In the same way, the secondary of the audio-frequency transformer 18 acts as a choke coil,'preventirTg passage of the high-frequency oscillations, fut conducting audio-frequency currents; Th circuit 10, therefore, is not disturbed by the potentials on the condenser 20, but is tuned by means of the adjustable condenser. 11 and carries continuous high-frequency oscillations which are impressed, through the condenser 19, upon the grid 9. The grid 9, therefore, carries both frequencies.

The act-ion of the righthand half of the device illustrated in Fig. 2 is like that described in connection with Fig. 1, amplifying the energy impressed upon the grid 9 and sending out high-frequency radiations, modulated at an audio frequency. The absence of any coupling between the anode circuit and the grid circuit is as complete in the formillustrated in Fig. 2 as it is in the form illustrated in Fig. 1 and the resulting advantages are the same.

Although I have illustrated and specifically described but a few modifications of my device, other variations will be apparent to those skilled in the art and the limited number of forms specifically described is not to be regarded as a limitation. No limitation except that necessitated by the prior art or indicated by the claims is intended.

I claim as my invention:

1. In a non regencrative, vacuum-tube amplifier including a grid, a filament and a plate, a grid circuit including a source of radio-frequency and a tuning device co-operating therewith to render said grid circuit resonant to said radio frequency, an allmetallic connection between the grid and filament for removing grid charge and stopping condensers on each side of said source of radio frequency preventing the grid charge from passing through said source of radio frequency.

2. In a non-regenerative, vacuum-tube amplifier including a grid, a filament and a plate, a grid circuit including a source of radio-frequenc and a tuning device co-operating therewit to render said grid circuit resonant to said radio frequency, an allmetallic connection between 'the grid and filament for removing grid charge, said allmetallic connection including a source of audio frequency and stopping condensers on each side of said source of radio frequency preventing the grid charge from passing through said source of radio frequency, said source of audio-frequency together with said stopping condensers presenting a high impedanceto the radio frequency In testimony whereof I affir my signature.

DR. 1G: LUDv 'IG Kt'HN.

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