US1654075A - Electric wave-transmitting means - Google Patents

Description

Dec. 27, 1927.

W. S. GORTON ELECTRIC WAVE TRANSMITTING MEANS Filed Aug. 16, 1922 Patented Dec. 27, 1927.

UNITED. STATES WILLIAM S. GORTON,

PATENT OFFICE.

OF EAST ORAN GE, NEW JERSEY, ASSIGNOB TO WESTERN ELEC- TRIO COMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

ELECTRIC WAVE-TRANSMITTING MEANS.

Application filed August 18, 1922. Serial 1T0. 582,112.

This invention relates to electric wave transmitting apparatus, especially push-pull electron discharge amplifier circuits, and aims to provide apparatus and circuits wh ch 5 will avoid the use of transformers and efliciently transmit currents of low frequency, and will in the case of the push-pull amplifier, obviate any necessity for insulating the amplifier batteries from ground.

The push-pull amplifier circuit, shown for instance in United States patent to Colpitts, No. 1,128,292, February 16, 1.915,, electric wave amplifier, has a transformer coupling in order to apply to the grids of two tubes voltages equal in amount but diiferin in phase by 180. It is at times undesirableto use transformer coupling in amplifiers, especially where currents of very low or very high frequencies are to be amplified. With an ordinary push-pull circuit, whenever one A side of the line is grounded, if-a non-inductive coupling such as a condenser-resistance or straight resistance coupling, instead of a transformer coupling, is used between the line and theamplifier, the cathodes of the tubes cannot be grounded as usual, since there would then be a short circuit from the ground at-the cathodes to the ground on the line. Thus, with such a circuit there is no alternative to grounding the grid of one of the tubes, which necessitates the obviously" undesirable course of insulating various batteries, or their equivalent, from ground.

In accordance with the invention a three electrode electron discharge tube circuit, arranged to give zero amplification, is connected in circuit between the line and the input circuit of one of the amplifier tubes of a push-pull amplifying stage, for the purpose of shifting the phase of the line voltage 180 'and thus providing the proper phase.

difference between the voltages applied to the the invention.

grids ofthe two amplifying tubes. Thus,

second stage is to be a push-pull stage to avoid distortion which would otherwise occur because of the large amount of power handled by the second stage. In this case 1t 13, as usual, desirable that the cathode of the amplifying tube of the first stage be grounded, and this means, even if there is no ground on the line outslde of the amplifier, one side of the circuit feeding the push-pull stage is grounded if the full line voltage is applied to the amplifymg tube of the first stage through a nonmductive coupling, or in other words, if the first stageis non-inductively coupled to the line and is not a push-pull stage.

The drawing s ows one embodiment of As 'shown' in the drawing, l1ne 1 andan outgoing line du'ctively coupled through a an incoming 3 are non-intwo stage amplifier 5, the second stage of which comprises tubes 7 and 9 connected in push-pull relation, the first stage comprising an amplifying tube 11 and a phase reversin tube 13. The output voltage of tube 11 is applied across the grid and filament of tube 7 through the condenser-resistance coupling comprising condenser 15 and resistance 17. The output voltage of tube 11 is also applied across the input leads which has its output leads connected to the gr d and filament of tube 13. A condenser 21 in the input lead of which is connected to the plate oftube 11 prevents flow of direct current from the B attery 23 of the amplifier 5 to the grid of tube 13. Plate current for tube 11 1s supplied from battery 23 through an impedance 25 which is preferably a non-inductive re: sistance. Similarly, battery 23 supplies plate current for tube 13 through resistance 27.

The output voltage of tube 13 is applied across the grid and filament of tube 9 through the condenser resistance coupling comprising a condenser 29 and a resistance 31. The output voltage of the second stage of the amplifier, that is, the output voltage of the push-pull stage comprising tubes 7 and 9, is applied to line 3 through the condenser resistance coupling comprising condensers 33 and 35 and non-inductive resistance 37 and 39. Plate current for tube 7 is of course, that of a potentiometer 19 the potentiometer supplibd from battery 23 through resistance 37; and plate current for tube 9 is supplied from battery 23 through'resistance 39.

The adjustment of potentiometer 19 is such that the voltage applied to the input circuit of the tube 9 is equal, though opposite in phase, to the voltage applied to the nput circuit of the tube 7.

The cathodes of all of the tubes are preferably grounded, as shown, to reduce the capacity to ground of the connecting wires and thereby decrease the tendency of the repeater to sing.-

Preferably, condensers 21 and 29 shouldeach have twice the capacity of condenser 15, since condensers 21 and 29 are serially interposed between the plate of tube 11 and the rid of tube 9. T e impedances of condensers 15, 21 and 29 should be small compared with the im edances of resistances 17, 25, and 31 in or- Ber that the phase of the voltage delivered by tube 11 may be changed by 180 degrees with ahigh degree of accuracy. It is particularly advantageous to employ this phase shifting expedient in the voltage-am lifying stages of an amplifier, where the istortion introduced by the tubes is much less than it is in the power stages. Thus, in the drawing, the first amplifying stage, comprising tubes 11 and 13, may well be a voltage amplification stage, and the second stage, comprising.tubes '7 and 9, may well be a power amplification-stage.

The invention claimed is:

1. The combination with a push-pull amlifier comprising two amplifying elements aving an input circuit including portions individual to said elements and a grounded portion symmetrically related to said elements, of an unsymmetrically grounded line and non-inductive means for coupling sai line to said individual portions of said input circuit.

2. Aline, two three-electrode electron discharge tubes each having a grounded cathode, and a non-inductive coupling means for applying the undivided voltage of the line to the cathode and the control electrode of one of said tubes and for applying the undivided voltage of the line in reversed phase to the cathode and the control electrode of the other tube.

3. A system comprising two electron discharge amplifiers connected in push-pull relation, an electron discharge tube having an output circuit and a control circuit,"

means for supplying electromotive force waves to said control circuit and one of said amplifiers in parallel, and means connecting said output circuit to said other amplifier.

4. A system comprising an electricwave transmitting ap aratus having a divided input circuit, a p ase chan 'in'g device, means for supplying, electromotive force waves to circuit of one of said means connecting said output circuit to another division of'said input circuit.

6. An amplifier circuit comprising a first stage and a' second stage, said second stage comprising two electron discharge tubes connected in push-pull relation and said first stage comprising an electron discharge amplifying tube, said circuit also com rising a phase reversing three-electrode e ectron discharge tube, means connecting theoutput circuit of said amplifying tube to the input pushull tubes and the input circuit of said p ase reversing tube in output circuit of said phase reversing tube to the input circuit of said other push-pull tube.

7. A line, three three-electrode electron dlscharge amplifying tubes, each having a grounded cathode, a non-inductive coupling means for applying the voltage of the line to one of said tubes, and a non-inductive coupling means for applying the output voltage of said one tube to the cathode and control electrode of another of said tubes and for applying said output voltage in reversed phase to the cathode and control electrode of the remaining tube.

8. In combination, a line having one side grounded, a pair of three-element space discharge devices connected in push-pull relation and having their cathodes both connected to ground, input terminals for said devices, and a non-inductive coupling connecting said line to the input terminals of said devices, said coupling including noninductive means for producing a 180 difference in phase in the line voltages 'applied to theinput terminals of the res ective parallel, and means connecting the space discharge devices, whereby said evices are adapted to amplify electrical variations received over said line.

9. A line, two three-electrode electron tubes each having a grounded cathode, and a non-inductive coupling means for transferring voltage between two electrodes of one of said tubes and said line without substantial phase change, and for transferring voltage between the corresponding two electrodes of the other tube and the line with phase reversal.

10. A system comprising two electronic amplifiers connected in push-pull relation,

connecting one division of said circuit and said phase changing device, in part llel, to a line, and means connecting the other of said divisions and said phase changing device.

In witness whereof, I hereunto subscribe my name this 8th day of August, A. D..

WILLIAM S. GORTON.

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