US2060508A

US2060508A - Short wave oscillator

Info

Publication number: US2060508A
Application number: US566604A
Authority: US
Inventors: Henry N Kozanowski
Original assignee: Westinghouse Electric and Manufacturing Co
Current assignee: CBS Corp
Priority date: 1931-10-03
Filing date: 1931-10-03
Publication date: 1936-11-10
Anticipated expiration: 1953-11-10

Description

Nov. 10,1936. H.- N. ROZANOWSKI 2,060,508

' SHORT WAVE OSCILLATOR Original Fi led Oct 3, 1931 WITNESSES: INVENTOR I I 7 I Henry Jiozdnowsfi'.

I A I J ATTOi2NE Patented Nov. 10, 1936 PATENT OFFICE SHORT WAVE OSCILLATOR Henry N. Kozanowski, Wilkinsburg, Pa., assignor to Westinghouse Electric & Manufacturing Company, a corporation of Pennsylvania Application October 3, 1931, Serial No. 566,604 Renewed August 30, 1934 10 Claims.

My invention relates to high frequency oscillators of the Barkhausen type for producing exceedingly high frequency oscillations.

In the Barkhausen oscillator, the control grid of a three-element tube is maintained at a positive potential, while the plate is maintained at either a low positive potential or at a negative potential. It is believed that this type of oscillator functions in the following manner:

The positive grid attracts the electrons and accelerates them to a speed sufiicient to make them pass through the mesh of the grid into the negative field between the grid and the plate. The negative field slows up the electrons and causes them to move back in the opposite direction, so that they again pass through the mesh of the grid. In this Way, the electrons oscillate about the grid, the grid remaining at a substantially constant potential.

While it has been possible to generate currents of a very high frequency (having wave lengths of the order of 90 cms.) by means of this type of oscillator, it has been very diflicult to obtain a satisfactory power output. Also it has been difficult to make an oscillator function at wave lengths much lower than 90 cms.

One object of my invention is to provide an oscillator of the above-mentioned type which will give a large power output.

Another object of my invention is to provide an oscillator that will oscillate at lower wave lengths than previously known oscillators of the above-mentioned type.

Still another object of my invention is to provide an oscillator of the above-mentioned type in which the frequency is substantially independent of variations in the voltage applied to the tube.

In practicing my invention, I employ two vacuum tubes which have their grids connected together and connected to a source of positive potential. The plates of the tubes are connected to a pair of Lecher wires, While the filaments are connected to a second pair of Lecher wires which are positioned parallel to the first pair. Formerly, the grids instead of the filaments were connected to the second pair of Lecher wires.

Other features and advantages of my invention will appear from the following description taken in connection with the accompanying drawing, in which Figure 1 is a circuit diagram of an oscillator constructed in accordance with my invention.

Fig. 2 is a view showing the physical arrangement of the Lecher wires.

Fig. 3 is a view illustrating the manner in which the Lecher may be made adjustable. I Referring to the drawing, the oscillator comprises a vacuum tube 10 having a cathode II, a grid l2 and a plate I3 and a vacuum tube I4 having a cathode [5, a grid l6 and a plate ll. The filaments are heated from a 110 volt line by means of a step-down transformer l8 which has the mid-point of its secondary winding l9 grounded. The filament ll of the tube i0 is negative terminal of the source of potential is grounded. With the oscillator adjusted to oscillate at 60 cms. a grid potential of 500 volts has been found preferable. If desired, the choke coil 21 may be omitted, since the grids l2 and 5 are at substantially zero radio frequency potential.

The plates l3 and I! are connected to the

conductors

28 and 29, respectively, of the first pair of Lecher wires. The ends of these wires remote from the tubes are electrically connected through a conductor 30, a low resistance meter 3| and a conductor 32.

The conductors 2B and 29 are connected through the

chokes

33 and 34, respectively, to the negative terminal of a source of potential 35. The positive terminal of the source is connected to ground. With the above-mentioned adjustment for operation at 60 cms., a negative potential of 110 volts on the plate was found desirable. One of the

choke coils

33 and 34 may be omitted, but it is preferred to employ both of them in order to make the circuit symmetrical.

The filaments H and I5 are connected to the

conductors

36 and 31, respectively, of the second pair of Lecher wires through

coupling condensers

38 and 39. mote from the tubes are electrically connected through a conductor 40.

The

condensers

38 and 39 may be omitted and. the Lecher

wires

36 and 31 connected directly to the filaments II and I5, providing they are connected to points on the filaments that are at the same potential. For example, the

condensers

38 and 39 could be omitted and the Lecher wire 36 connected to the point X on the filament II and the Lecher wire 37 connected! The ends of the conductors reill to the point Y on the filament I 5. It will be noted that points X and Y are connected to the same terminal of the secondary l9.

The use of the filament resistor 22 is important, because it is diiiicult to obtain two tubes having filaments which have the same electron emitting characteristics. This is especially true of vacuum tubes which have thoriated tungsten filaments. In the Barkhausen oscillator, the grids are maintained at such a high positive potential that the tubes operate at almost their saturation current value. Since, in this case, a grid will remove practically all of the electrons from the filament that the filament is capable of emitting, the tube having the best electron emitting filament will become overheated, while the other tube will remain cool. In my circuit, I place the resistor 22 in series with the filament having the best electron emitting characteristics, so that the filament may be operated at .a lower temperature to reduce its electron emissivity. In one embodiment of my invention the tubes employed were UX 852 tubes.

The relative location of the Lecher wires is illustrated in Fig. 2. It will be noted that one pair of Lecher wires is placed directly above the other pair whereby both pairs of wires are electrically coupled to each other. These wires or conductors are preferably of copper tube 4! having telescoping joints so that the length of the conductors may be adjusted. Each conductor is adjusted so that it is about one wavelength long.

It has been found that, by employing two vacuum tubes of a given size in the manner described above, the output of the oscillator is much more than double the output of any known oscillator of this type employing a single tube of the same size.

It may be noted that the output of my oscilator may be modulated by varying the plate voltage as shown diagrammatically by the element 42.

The frequency at which the oscillator operates is determined by the length of the plate Lecher wires, while the length of the filament Lecher wires controls the amplitude of the oscillations.

' The grid and plate voltages may be varied within wide limits and the frequency remains at the value determined by the plate Lecher wires. This is in marked contrast to the behavior of other Barkhausen oscillators.

Various modifications may be made in my invention without departing from the spirit and scope thereof, and I desire, therefore, that only such limitations shall be placed thereon as are imposed by the prior art and are set forth in the appended claims.

I claim as my invention:

1. An oscillator comprising two vacuum tubes, each tube having a cathode, an anode, and a grid, means for connecting said grids together electrically, means for maintaining said grids at a positive potential with respect to said cathodes, a pair of Lecher wires and means for connecting them to said cathodes, a second pair of Lecher wires positioned substantially parallel to said first pair and connected to said anodes said pairs of Lecher wires being coupled, and means for applying a potential to said anodes lower than one of said pairs of Lecher wires, said anodes being connected to the other of said pairs of Lecher wires, means for applying potentials to said cathodes and anodes, means for electrically connecting said grids and means for maintaining them at a higher potential with respect to said cathodes than said anodes.

3. An oscillator of the Barkhausen type comprising a pair of vacuum tubes, each having a cathode, a grid and an anode, means for maintaining said grids at a positive potential with respect to said cathodes, means for maintaining said anodes at a negative potential with respect to said cathodes, a pair of oscillatory circuits, means for coupling said anodes to one of said circuits, means for coupling said cathodes to the other of said circuits, said pairs of oscillating circuits being electrically coupled to each other.

4. An oscillator of the Barkhausen type comprising a pair of vacuum tubes, each having a cathode, a grid, and an anode, means for maintaining said grids at a positive potential with respect to either of said cathodes, means for maintaining said anodes at a negative potential with respect to said cathode, a pair of Lecher wires connected to said cathodes and a second pair of Lecher wires connected to said anodes, said pairs of Lecher wires being electrically coupled.

5. An oscillator of the Barkhausen type comprising two vacuum tubes, each having a cathode, a grid, and an anode, means for maintaining said grids at a positive potential with respect to either of said cathodes, means for maintaining said anodes at a negative potential with respect to said cathodes, a pair of Lecher wires coupled to said anodes, a pair of Lecher wires coupled to said cathodes, said first pair being electrically coupled to said second pair, and means for separately controlling the amount each cathode is heated.

6. An oscillator comprising two electric discharge tubes spaced apart from each other, each having a cathode, a grid and an anode, a pair of coupled conductors extending each from one of said anodes in a substantially parallel relationship and having distributed capacity, a similar pair of conductors connected to said cathodes, means for maintaining a potential difference between the cathode and anode of each of said electric discharge tubes, a further conductor materially shorter in length than either of said two conductors interconnecting the grid electrodes of said tubes and means for maintaining a higher potential difference than that above-mentioned, between the grid electrode and the cathode of each said electric discharge tubes.

7. An oscillator comprising two electric discharge tubes spaced apart from each other, each having a cathode, a grid and an anode, two conductors, each of which is substantially longer than the distance separating said vacuum tubes,

of wires connected to said anodes and coupled to each other both magnetically and electrostatically to constitute a Lecher system, electrical connections between said grids, a pair of wires similarly coupled and connected to said cathodes to constitute a second Lecher system, means for electrically connecting said pair of anode Lecher Wires, said pair of cathode Lecher wires and said grid interconnection to each other to complete circuits between said electron discharge tubes, and means for impressing a positive potential on said grid electrodes relative to both said cathodes and anodes.

9. An oscillator comprising two electric discharge tubes spaced apart from each other, each having a cathode, a grid and an anode, three connections each joining an electrode of one tube with the corresponding electrode of the other tube, at least one of said connections comprising substantially parallel coupled conductors having distributed capacity and constituting in itself a Lecher system, the connection joining said cathodes being parallel along its length to said Lecher system, and means for placing the grid electrodes at a positive potential relative to said anodes and cathodes.

10. An oscillator comprising two electric discharge tubes spaced apart from each other, each having a cathode, a grid and an anode, three connections each joining an electrode of one tube with the corresponding electrode of the other tube, the connection joining the cathodes with each other comprising substantially parallel coupled conductors having distributed capacity and constituting a Lecher system and the connection joining the anodes with each other also constituting a similar Lecher system, and means for placing the grid electrodes at a positive potential relative to said anodes and cathodes.

HENRY N. KOZANOWSKI.