US1682703A

US1682703A - Radio apparatus

Info

Publication number: US1682703A
Application number: US415523A
Authority: US
Inventors: Donald G Little
Original assignee: RCA Corp
Current assignee: RCA Corp
Priority date: 1920-10-08
Filing date: 1920-10-08
Publication date: 1928-08-28
Anticipated expiration: 1945-08-28

Description

Aug. 2 8, 192s. 1,682,103

RADIO APPARATUS Filed Oct. 8, 1920 l MyW ATTORNEY Patented Aug. 28, 1928.

UNITED STATES PATENT OFFICE.

DONALD LITTLE, QF DGEWOOD, PENNSYLVANIA, ASSIGNOR TO RADIO CORPORA- TION OF AMERICA, A (LORPORATION` OF NEW YORK.

RADIO APPARATUS.

Application led October 8, 1920. Serial No. 415,523.

My invention relates to radiol apparatus of the type in which an oscillation circuit is adapted to be tuned to various wave-lengths within a given range, and its object is to provide a system whereby the necessary adjustments or manipulations for changing the wave-length may be reduced to a minimum.

A more specific object of my invention is to provide a radio-transmitting circuit of uniform output over a large range of wavelengths. A further object is the attainment of the aforesaid objects with minimum loading and minimum adjustments of loading of the various coupled circuits.

These and other objects are obtained by means of the apparatus hereinafter described and claimed, and illustrated in its preferred form. in the accompanying drawing, in which the figure is a diagrammatic View of a transmitting set embodying my invention.

The apparatus is shown as consisting of an oscillation circuit 1, comprising an antenna'2 and a variable inductance 3, whereby said circuit may be tuned to various wave-lengths within a given range. If desired, a rough adjustment only may be made with the variable inductance 3, the final tuning being accomplished by means of a variable shunt condenser 4. The inductance 3 is shown connected to ground at 5. The inductance 3 is 1n inductive relationship with a coil 6, the terminals of which are connected respectively to the filament 7 and the plate 8` of a three-electrode vacuum tube 9. The grid 10 of said tube is connected to one terminal of a second inductively related coil H, thenther terminal of which is connected to the filament 7 A grid condenser 12 is shown bridged by a resistance At any convenient point inl the plate circuit of the vacuum tube I place any suitable source of energy, indicated by the signs plus and minus, which is bridged by a condenser 14, although my invention is not limited to the use of a direct-current source.

The usual preventive impedances 15 are shown in the conductors 16 and 17 leading to said source.

Coil 6 is bridged by a suitable capacity 18, forming a tuned circuit. When no current is flowing in the antenna circuit, the circuit comprising the coil 6 and capacity 18 is arranged to have a wave-length which is shorter than the shortest wave-length to which said antenna circuit may be adjusted. When current is flowing through the antenna circuit, the latter, as Well as the local plate circuit, comprising the coil 6 and capaclty 18, Oscillate at the wave-length determined by the constants of the antenna circuit.-

f If desired, the `common terminal of coils 6 and 11, which is joined to the filament 7, may be connected to ground by means of the conductor 19.

I have discovered that the plate circuit functions as an untuned circuit in that it is not tuned to the wave-length of the antenna circuit, but does transmlt impressed waves of the wave-length to which the antenna circuit is tuned, whereas the plate circuit is tuned to the extent that any variation of the plate condenser 18 changes the power output of the antenna circuit. In practice, upon setting the plate condenserl 18 to the desired adjusted position, its adjustment is not disturbed.

In the practice of my invention, the output over a wide variation of antenna capacity and resistance is maintained substantially uniform and the load on the Oscillating tube or tubes remains practically constant. The

desired particular wave-length sought to be emitted from the antenna is readily regulated by solely varying the variable inductance 3 and variable condenser.

l Since the parallel resonant circuit 6, 18 is serially included in the plate circuit, and Since said parallel resonant circuit is tuned to a wave-length slightly less than the lowest wave-length to which the antenna circuit is to be tuned, the circulating current in the coil 6 will decrease as the frequency departs further and further from the condition of exact resonance. Hence, the effective ampereturns of thecoupling coil 6 are decreased as the antenna wave-length is increased, there by counteracting the effect of the increased ampere-turns in the tuning coil 3 and also maintaining a substantially constant output over a considerable range of wave-lengths, with a single adjustment of the tuning coil 3. Whereas I have described my invention by reference to specific forms thereof, it will be understood that l do not regard my invention as being limited to the exact details of construction shown, as many changes and modifications may be made without departing from the 'spirit of the invention as deinedby the appended claims.

I. claim as my invention :w-

1. In a radio transmission system, an oscillation circuit adapted to be tuned to various wave lengths within a given range, in combination with an oscillation generator, including said circuit and comprising an amplifier having an input circuit and an output circuit, said circuits having a feed-back arrangement whereby some of the power from the output circuit is impressed upon the input circuit,

and. said amplifier delivering to said output circuit a relatively large power upon the reception of a relatively small power from said input circuit, and means including a local source for supplying said amplifier with energy, one of the circuits of said generator havingr included therein a circuit with a natural wave length outside the range of wave lengths of said oscillation circuit, said included circuit being coupled to said oscillation circuit and the constants of the coupled circuits being such that theinterchange of power between them may be substantially the same regardless of the adjustment of said oscillation circuit.

2. In a radio transmission system, an oscillation circuit adapted to be tuned to various wave lengths within a given range, in combination with an oscillation generator, including said circuit and comprising an amplifier having an input circuit and an output circuit, said circuits having a feed-back arrangement, whereby some of the power from the output circuit is impressed upon the input circuit, and said amplifier delivering to said output circuit, a relatively large power upon the reception of a relatively small power from said input circuit, and means including a local source of energy for supplying said amplifier, one of the circuits of said generator having included therein a circuit with a natural wave length shorter than the shortest wave length to which said oscillation circuit may be adjusted, whereby the interchange of power between said circuits may be substantially the same regardless of the adjustment of said oscillation circuit.

3. In a radio transmission system, an oscillation circuit including a variable inductance and a capacity capable of but slight variation, whereby said circuit may be tuned to various wavelengths within a given range, in combination with an oscillation generator, including said oscillation circuit and comprising an amplifier havin an input circuit and an out put circuit, sai circuits having a feed-back arrangement, whereby some of the power `from the output circuit is impressed upon the input circuit, and said amplifier delivering to said output circuit a relatively large power upon the reception of a relatively small power from said input circuit, and means including a local source for supplying said amplifier power between said circuits may be substantially the same regardless of the adjustment of said oscillation circuit.

4. In a radio-transmission system, the combination with an oscillation circuit including a variable inductance and a capacity capable of but slight variation, whereby said circuit may be tuned to various wave-lengths within a given range, of a threeelectrode vacuum tube having a late circuit and a grid circuit, both of said ast mentioned circuits being inductively coupled with said variable inductance, one of said last-mentioned circuits including a parallel resonant circuit, the inductive clement of which forms one member of the vcoupling ofthis tube circuit with said variable inductance, said parallel resonant circuit having a natural wave-length which is shorter than the shortest wave-length to which said oscillation circuit may be adjusted, and means whereby a source of energy may be connected to said vacuum tube, the constants of said circuits being such that the power delivered to said oscillation circuit is substantially constant for all wave-lengths.

5. In a radio-transmission system, the combination with `a secondary circuit adaptedtobe tuned to various wave-lengths within a given range, of an oscillation generator including said secondary circuit and having a power circuit and a controlling circuit for controlling the current in said power circuit, and means for supplying energy thereto said oscillation-generator circuits including a primary circuit coupled to said secondary circuit, and said primary circuit having a natural wavelength not included in the range of variation of said Secondary circuit.

6. In a radio-transmission system, the combination with an oscillation circuit adapted to be tuned to various wave-lengths within a given range, of an oscillation generator including said oscillation circuit and compris ing an amplifier having a controlling circuit and an output circuit coupled to said controlling circuit and a source of energy connected to said output circuit, said output circuit serially including a parallel resonant circuit inductively coupled to' said oscillation circuit and having a constant natural wave-length which is shorter than the shortest wave-length of said oscillation circuit.

7. In radio apparatus, the combination with an oscillation circuit including a substantially constant capacity and a variable inductance, whereby said circuit may be tuned to various wave-lengths within a given range, of a second circuit inductively coupled with said variable inductance, said second circuit having anatural wave-length which is shorter than the shortest wavelength to which said oscillation circuit may be adjusted, the constants being such that the interchange of power between said circuits is substantially the same regardless of the adjustment of said oscillation circuit, an output circuit including said second circuit and including also a source of energy and a variable impedance device, a controlling circuit for varying said variable impedance, and means for coupling said controlling circuit to receive power from said output circuit. i

8. In radio apparatus, the combination with an oscillation circuit including a substantially constant capacity and a variable inductance, whereby said circuit may be tuned to various wave-lengths within a given range, of a parallel resonant circuit inductively coupled to said variable inductance, said parallel resonant circuit having forced oscillations and having a constant natural wave-length which is shorter than the shortest wave-length of said oscillation circuit, a variable impedance device, electroeresponsive controlling means therefor, a source of energy, an output circuit including said variable impedance device, said source of energy and said parallel resonant circuit, and means for coupling said controlling means to be responsive to the electrical conditions in saidoutput circuit.

9. In radio apparatus, the combination with an oscillation circuit including a substantially constant capacity and a variable inductance, whereby said circuit may be tuned to various wave-lengths within a given range, of a parallel resonant circuit inductively coupled to said variable inductance, said parallel resonant circuit having forced oscillations 'and having a constant natural wave-length which is shorter than the shortest Wave-length of said oscillation circuit, an electron tube having a space-current path, controlling means therefor, a source of energy, an out put circuit including said space-current path, said source of energy and said parallel res` onant circuit, and means f or coupling said controlling means to receive power from said output circuit.

10. In a radio system, a tunable oscillation circuit, a circuit coupled thereto, said coupled circuit having'a tuning device in addition to the coupling, the natural period of said coupled circuit being outside the range of frequencies to which said oscillation circuit is tunable.

11. An electron-discharge oscillator comprising a discharge device having electrodes,

a tuned frequency-determining circuit associated therewith, a circuit including the capacity between two ormore of said electrodes capable of acting as a frequency-determining circuit for waves of a parasitic frequency other than the ldesired frequency, and means associated with said device for establishing said parasitic frequency at such' a value other than the desired frequency as will prevent the reduction of power output at the desired frequency.

l2. An electron discharge oscillator comprising a discharge device having electrodes, one of said electrodes being a cathode having a ground connection, a tuned frequency-de termining circuit connected to ground and insulated from said device except for said ground connection, a circuit separate from said tuned frequency-determining circuit and including the capacity inherent in said device and its leads, said circuit tending to act as a frequency determining circuit for parasitic oscillations, and means attached to said circuit for preventing the tendency of said device to oscillate at said parasitic frequency from reducing the power output at the de sired frequency.

13. In a power oscillator, a space discharge device having an anode, a cathode, and a control element for controlling the discharge between the anode and the cathode, a tuned frequency determining circuit coupled to the circuits of said device an inductance coil in the anode-cathode circuit coupled to said tuned circuit,and a condenser shunted around said coil for increasing the power factor of the anode-cathode'circuit at the frequency of generation, said coil and condenser shunted there-around being of such values as to form a resonant combination only at a frequency considerably different from the frequency of generation.

14. In a radio transmission system, the combination of an oscillation circuit, means for varying the tuning of said oscillation circuit over a range of wave lengths, a threeelectrode vacuum tube having grid and plate circuits inductively coupled to said oscillation circuit, a source of energy connected to said vacuum tube, and included in one of said tube circuits a parallel resonant circuit having a natural wave length different from that of said oscillation circuit, the constants of said circuits being such that the power delivered to said oscillation circuit is substantially constant for all wave lengths within said range.

In testimony whereof I aihx my signature.

DONALD G. LITTLE.