US1192126A - Wireless-telegraph transmitter. - Google Patents

Description

A. SHAW. WIRELESS TELEGRAPH TRANSMITTER;

APPLICATION FILED JUNEZQ, 1912- Patented J lily 25, 1916.

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A. SHAW} WIRELESS TELEGRAPH TRANSMITTER. APPLICATION FILED 11114529. I912.

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FIG4 F1655 Patentd July25, 1916.

A. SHAW. v WIRELESS TELEGRAPH TRANSMITTER.

APPLICATION FILED JUNE-29, I912. I 1,192,126, Patented July 1916.

3 SHEETS-SHEET 3- less-Telegraph Transmitters, of which the;

, ED STATES PATENT FFI@ ARCHIBALD SHAW, F RANDWICK, NEAR SYDNEY, SOUTH WALES, AUSTRALIA.

WIRELESS-TELEGRAPH TRANSMITTER.

Specification of Letters Patent.

Patented July 25, 1916.

Application filed June 29, 1912. Serial No. 706,638.

'To all whom it may concern:

Be it known that I, AROHI ALD SHAW, asubject of the King of Great Britain and Ireland, residing at Dutruc street, Randwick, near Sydney, in the State of New South Wales, Australia, have invented certain new and useful Improvements in \Vire.

' following isa specification.

1 0 1 graph'transmitter.j An alternating current My invention consists in a wireless telege'nerator wound and driven to produce about 500 cycles per second is used in the primary power circuit. generators at much lower rates of current reversal but with inferior results, The generator current isstepped up in a transformer (closed core .by preference) to a voltage of about 28,000. The exciting circuit contains capacity ari inductance and it includes a rectifying break or spark gap,

which will be described ereinafter in greater detail. The exciting circuit is usually connected to the radiator, so as to energize it by shock excitation, but the couplingmay be inductive. that the exciting circuit and the radiator should be in syntony when coupled electrostatically or conductively. In practice, the frequency of the exciting circuit is higher than the frequency of the radiator when coupled electrostatically or conductively. The constants of the exciting circuit are adjusted so that the condenser charges and discharges once in every half cycle oft-the primary current.

. adjusted with regard to the required wave length,'and so as, as far as possible, to increase the radiating qualities at the expense of the oscillating qualities thereof, the object being to enable the aerial to radiate as freely as possible the energy thrown into it by the exciting circuit, and to cause the exciting circuit to maintain excitation of the radiator with unidirectional impulses following each other with extreme rapidity while the primary circuit is closed.

One of the electrodes of the rectifying break or spark gap is in the form of .a fiat surface and the other in the form of a conie11 blunt nosed nozzle set at from one half inch to five-eighths of an inch therefrom depending on the voltage, through which nozzle a finejet of a pure or a mixed gasair being used in practice-is forced under high pres- I have used such It is unnecessary The radiator constants arev sure so as to impinge squarely against the face of the flat electrode. The electrodes are best made of copper or silver, zinc showing a tendency to pit at the place of impact of the gas jet. The diameter of the gas passage is proportioned to the power of the transmitter, and is about one sixty-fourth of an inch in diameter in the case of a two K-W the pressure used is preferably about 110 pounds .on the square inch, at which point I have obtained maximum effect under theconditions hereinbefore described. The working pressure may be varied to some extent above or below about 110 pounds per square inch directly proportional to the voltage in the exciting circuit. If a pressure approximating toward 150 pounds per square inch is used, the flash or blaze assumes another form and the beneficial effects sought are seriously minimized or no longer obtained. At pressures substantially below 50 pounds per square inch the effect is so far minimized as to be of smallworking value if not practically useless, the unidirectional character of the discharge being then affected or entirely lost. The discharge across the gap is characteristically different from the spark obtained between the fixed or rela tively moving pencil or ball electrodes ordinarily used in the gap of an oscillating circuit; and it is not in the nature of an are.

Measurement of the current in the radiator by ammeter shows, for any given energy; in the generator circuit, a higher reading than is obtainable when the radiator is energized by an oscillating feeding circuit containing a spark gap with solid pencil shaped or spherical electrodes, and hence a high efliciency of transmission is attained. In consequence of the extreme rapidity at which the radiator is repeatedly excited while the sendin key is closed, an effective wave train 'a screw adjustment in the leading-in insulator to enable the operator to vary the length of the gap readily. The stem G of the fiat nosed cone nozzle electrode K is tubular, and it is connected by a rubber hose M to a source m of air or gas under the necessary pressure. N is a valve in the hose M.- The forward end of the nozzle electrode K is coned externally. P is an axial hole in the electrode K.- The two electrodes 1 K and L are arranged in axial alinement so that the gas jet impinges squarely on the face of the flat electrode. Q, is an inclosing box of wood, supported on heavy insulating feet R. I and J are leading-in insulators in the box Q. The spent air or gas finds exit through-the joints in the case A and the box Q. The noise of the break is dampened by these inclosures. The break is kept cool as a result of the absorption of heat by the expanding gas. I

In Figs. 4; and 5: T is the radiator, shown in the form of an aerial wire, 15 condenser in the exciting circuit, t variable loading coil for tuning purposes, X earth, U variable inductance in the exciting circuit, m air or gas pump, M pipe from pump m to gap electrode, V step-up transformer, W sending key, Y impedance coil, Z primary alternating generator.

In the electrostatic and inductive forms of the coupling shown in Figs, 4 and 6 the condenser t is common to both the radiator and the exciting circuit.

In the conductive coupling arrangement shown in Fig. 5 it is necessary'to provide a separate condenser t in the radiator circuit, as the condenser t is not included therein.

In the inductive coupling arrangement shown in Fig. 6 the connection R of the earth line is variable ,on the inductance coil U, the connections S and S of the excit-- ing circuit to this coil U being also made variable; in this arrangement the radiator and the exciting circuit should be in syntony.

An essential feature of the invention is the employment of a gas blastat a pressure varying between about 50 pounds and 140 a pounds per square inch and preferably about 110 pounds per square inch, more or less, directed through a fine axial hole in a tubular electrode against the face of a solid electrode across the spark gap in the ex-f Heretofore spark gap electrodes have beefi P PO d one of which has the formof a point or pencil directed toward the other, which latter-1s made with a plane surface,

flow of sparks and preventing oscillatory flow of current across the gap; and it has been a common practice toplay a jet of air on a spark gap, to effect cooling and to prevent arcmg. These methods do not produce a blaze or torrential flash of current such as is produced when the electrodes are formed as a blunt nosed cone and a fiat plate with a needle jet of gas at pressure of 110 lbs. per square inchmore orless passing through the cone electrode and directed axially from the point thereof onto theflat face of the plate electrode. In the case of the arrange- -with the object of obtaining a unidirectional ment used by me a very large volume of energy passes over a short gap, which oflers,

other things being equal, minimum resistance, and this energy displaysitself in the exciting circuit in the form of unidirectional impulses of high frequency which may be transmitted as a. train of damped waves. With any material difference in the shape or arrangement ofthe electrodes or in the gas pressure the characteristic effects described are either procured indifierently or irregularly or entirely lost, and the. volume of energy which can be employed usefully in the transmitter is of a relatively lower order.

The operation is as follows :The alter-- nator Z delivers current at a periodicity 'of 500 per second, and when the sending key W' is closed this current is stepped up. in

the transformer V to a voltage of about 28,000, charging the condenser t. Air is fed to the gap electrode K in the exciting circuit through the hose M from the pump on under a pressure of lbs. per square inch. If the voltage in the exciting circuit is sub stantially over or under 28,000 a proportionately greater or less pressure is used."

The values in-the. excitingcircuit are pro portioned so that the condenser at will charge and discharge once in every half cycle'of the primary current. The radiator T is coinstructed to radiate freely inthe frequency required for transmission, tuning being effected by means of the variable loading inductance t. The condenser discharges cross the gap KL in one direction only ize and feeds the radiator T with impulses of great rapidity.

In the arrangement shown in F1g.' 4 the coupling is electrostatic, in Fig. 5 conductive, and in Fig. 6 inductive but in each case the frequency of the radiator is determined by its own constants, and the frequency of the exciting circuit is proportioned to the frequency of the generator. p

Throughout this specification I have, in deference to established usage,employed the term spark gap referring to the gap in the circuit across which the condenser discharge jumps. It will be understood, howradiator exciting circuit including a condenser and proportioned to fix its charging and discharging period in correspondence with the period of reversal of the primary alternating current and containing electrodes in the form of a blunt nosed cone andv a fiat plate, with a short intervening gap betweent'hem, said cone electrode having a hole through it directed toward the plate electrode, in combination with means for forcing a needle jet of gas under a pressure of approximately 110 lbs. per square inch through said hole.

, 2. In a Wireless telegraph transmitter. including a source of high potential alternating current in a primary circuit, the combination with an exciting circuit coupled to a radiator and connected to said source of alternating current and proportioned to be charged and discharged once every half cycle of the primary alternating current, of

a short gap in said exciting circuit the elec-j trodes of which gap are respectively a blunt nosed cone and a fiat plate, said cone being pierced with a hole, and means for forcing gas through said hole under a pressure approximating to 110 lbs-per square inch squarely against the face of said flat electrode.

8. In a wireless telegraph transmitter, the combination of a primary circuit including a primary source of high tension alternating current, a free radiator which is a. poor oscillator and has its values proportioned to the transmitting wave length, an exciting circuit feeding said radiator on the shock excitation principle, said exciting circuit proportioned to be charged and discharged once every half cycle of the primary alternating current and having a gap theelectrodes of which are located at a relatively short distance apart and consist respectively of a flat plate and a blunt nosed cone, means for forcing a needle jet of gas through. a

hole in said cone electrode under a pres-- sure of approximately 110 lbs. per square inch against the face of said flat plate electrode, said source of high tension primary alternating current of high initial periodicity energizing said exciting circuit, and a sending key in the prima r y circuit.

4. In a wireless telegraph transmitter, a radiator exciting circuit and a primary circuit inductively connected thereto, said primary circuit including a source of alternating,electro-motive-force, said exciting circuit includin a condenser and proportioned to fix its charging and discharging period in correspondence with the period of said source, a rectifying spark gap in said exciting circuit, an aerial connected to one side of said condenser, and means including a variable inductance for connecting said aerial to the ground.

5. In a wireless telegraph transmitter, the combination with a step-up transformer having in its primary circuit a source of alternating electromoti\'e-fOrce and a sending key, of a rectifying spark-gap in the secondary circuit, a condenser in series with said spark-gap, a variable inductance in said secondary circuit between said spark gap and condenser whereby said secondary circuit may be proportioned to be charged and discharged once every half cycle of said primary alternating circuit, an aerial connected to one side of said condenser, the other side of said condenser being grounded, and a variable inductance between said condenser and the ground whereby the aerial may be tuned.

6. In a wireless telegraph transmitter, the combination, with a step-up transformer having in its primary circuit a source of alternating electro-motive-force and a sending key, of a rectifying spark-gap in said secondary circuit, a condenser in series with said spark-gap, inductance in said secondary circuit between said spark gap and the point of connection of one side of said condenser, an aerial connected to one side of said condenser, means for proportioning said primary and secondary circuits so that the latter shall be charged and discharged once every half cycle of the former, and means including a variable induction for grounding the side of said condenser away from said aerial.

7. In a wireless telegraph transmitter, the combination, with a step-up transformer having in its primary circuit a source of alternating electro-motive-force and a sending key, of a secondary circuit comprising a rectifying spark-gap which consists of a pair of spaced electrodes in the form of a blunt nosed cone and a fiat plate respectively, said cone electrode having an axial bore normal to the plane of said plate electrode, and means for blowing through said bore gas at a pressure of more than fifty pounds per square inch and less than one hundred and fifty pounds, per square inch, together with a condenser connected in series with said spark gap-andsuitable aerial connections to said condenser.

8. Wireless telegraph transmitting apparatus comprising a radiating circuit of low 5 oscillative frequency, an exciting circuit of higher oscillative frequency than said radiating circuit, a unidirectional current gap whereby groups of impulses are fed into said radiating circuit at a frequency corresponding to thatof the exciting circuit, a

source of} alternating electro-motive-force operatively coupled to said exciting circuit, and means for establishing'and disestablishing operative connection between said source and said exciting circuit.

\ 9. Wireless telegraph-transmitting apparatus comprising a radiating circuit of low oscillative frequency and comparatively high dissipation rate, in combination with means for feeding into said radiating circuit groups of unidirectional high tension impulses, said groupsbeing spaced apart by equal intervals which intervals are greater than theosc'illative frequency'of said radiating circuit.

(iopiesof this patentinay be obtained for containing a condenser and having a frequency higher, than that of said radiating circuit, said charging circuit being electrostatically coupled to said radiating circuit, and means for governing the energization of said condenser whereby distinguishable signals may be afiorded.

In testimony whereof. I have afiixed my signature in presence of two witnesses.

ARCHIBALD SHAW.

Witnesses v W. J. DAVIS, S. BECK.

five cents each, by addressing .the Commissioner of Patents, Washington, D. G.

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