US2095990A - Oscillation generator - Google Patents

Description

Oct. 19, 1937. LlNDENBLAD 2,095,990

OSCILLATION GENERATOR Filed Feb. 16, 1935 MHZ/1,4703

INVENTOR. NILS E. LINDENBLAD F 7% wm,

ATTORNEY.

Patented Oct. 19, 1937 PATENT OFFHCE OSCILLATION GENERATOR Nils E. Lindenblad, Port Jefferson, N. Y., assignor to Radio Corporation of America, a corporation of Delaware Application February 16, 1935, Serial No. 6,814

Claims.

My present invention relates to short wave oscillation generators and has as its main object to provide an improved resonant line controlled oscillation generator making use of a linear tu- 5 bular frequency controlling element one half wave length long. This construction affords the advantage that the oscillator becomes inexpensive and simple to construct besides being highly efficient in operation.

A further object of my present invention is to provide an improved metering system for indicating optimum operation of an alternating current system and in particular a line controlled oscillation generator.

In the accompanying drawing, I have shown one way of carrying into effect the objects of my present invention, the drawing illustrating, diagrammatically, a push-pull oscillation generator whose frequency is stabilized and controlled by a resonant line substantially one half wave length long at the desired operating frequency.

Turning to the drawing, the tubular hollow cylindrical line 2 is substantially one half wave length long at a desired operating frequency. The line 2 is insulatedly mounted by the supports shown within the concentric tubular container 4 grounded by means of suitable grounding connections diagrammatically illustrated at 6. The midpoint of the line 2 is connected to the shielding shell 4 through the grid leak and resistance combination 8. At points symmetrically opposite the midpoint Ill on the linear or substantially straight resonant line 2, such as the points or rings l2, M, are connected the grids l6, I8 of vacuum tubes 29, 22. Vacuum tube 20 is also provided with a plate 24 and cathode 26, and vacuum tube 22 contains plate or anode 28 and cathode or filament 3G. The cathodes are connected directly to ground, as shown, or they may be fed through choke coils with heating current so that the cathodes fluctuate at a radio frequency potential with respect to ground, or they may be connected together by means of the tubular cathode system described more fully in my United States Patent No. 2,052,576, granted September 1, 1936, on copending application Serial No. 603,- 310, filed April 5, 1932, in which event the oathodes will fluctuate out of phase and at some radio frequency potential with respect to ground. Between the plates there is connected a tuned circuit 32 having a lumped inductance 34 and a variable tuning condenser 36. The plate circuit 32 may be replaced by a single looped conductor of sufficient length, if desired, and this single loop having substantially uniformly distributed inductance and capacity may be shunted by a tuning condenser.

Signal input energy may be applied through the transformer 4|] connected in series with the plate voltage supply lead 42, and output energy maybe taken through blocking condensers M and fed through transmission line 46 to a suitable radiating antenna, not shown.

Oscillation generation takes place primarily by virtue of interelectrode feedback through the tubes 20, 22, correct grid bias being maintained by the grid leak and condenser arrangement 8.

The resonant line 2, because of its linearity, simplifies construction and coincident with that there is a saving in constructional costs as compared to other forms of frequency controlling systems.

The line 2, and also the concentric cylinder 4 therefor, is preferably made of a material of high conductivity, such as copper, and is preferably made of fairly large diameter so as to be of low loss and as to make the power factor of the frequency controlling line 2 a minimum. The line 2 while preferably one half wave length long may be made any odd number of half wave lengths long. For all practical purposes, I have found that a half wave length linear line will prove highly satisfactory.

To determine when the system is operating correctly, the thermogalvanometer 5B is provided. One side 52 of this galvanometer is grounded as shown and the other is connected to a metallic stud 54 frictionally or screw-threadedly or otherwise movable within the insulating bushing 56. This thermogalvanometer will give a reading proportional to the line voltage or current, that is to say, to the line voltage or current on the line 2. The stud 54 is moved with respect to the line 2 such that a desired reading appears upon the thermogalvanometer when the system is operating properly. This desired reading may be made a maximum deflection or some substantial deflection of the thermogalvanometer. Once that reading has been determined, it will only be necessary thereafter, in order to obtain proper operation of the system, to adjust the voltagesv supplied the tubes, the tuning of the plate circuit and the adjustment of the filament circuit until the same current deflection appears in the thermogalvanometer 50.

It is to be distinctly understood that the term ground, as used in the specification and appended claims, is intended to mean any point 55 or surface of zero or relatively fixed radio frequency potential.

Having thus described my invention, what I claim is: V

1. An oscillation generation system comprising a straight linear frequency controlling element having a length equal to a multiple of half the fundamental wave, a pair of electron discharge devices, each having a control grid and an anode, connections from said control grids to points on said element which are symmetrically and oppositely disposed with respect to the electrical center of said element, and a parallel tuned output circuit of inductance and capacitance connected between said anodes.

2. An oscillation generation system comprising a straight linear frequency controlling element having a length equal to half the fundamental wave, a pair of electron discharge devices, each having a grid, cathode and anode, a. connection between said cathodes and ground, and

connections from said grids to points on said 7 element which are symmetrically located with respect, to the electrical center of said element, a circuit including a resistance from the electrical center of said element to ground, and a tuned output. circuit coupled to said anodes.

3. An oscillation generator system' comprising a low power factor straight linear element having a length equal to an odd multiple of onehalf the fundamental wave, and a pair of electron discharge devices having their control electrodes connected to said linear element at points which are symmetrical with respect to the electrical center or mid-point thereof, and a tuned output circuit coupled to the anodes of said electron discharge devices.

4. An oscillation generation system comprising a hollow, straight, linear, frequency controlling element having a length equal to a multiple of half the fundamental wave, a pair of electron discharge devices each having an anode, cathode and a control electrode, a connection from the electrical center of said frequency controlling element to said cathodes, connections from said control electrodes topoints on said element which .are symmetrically located with respect tosaid electrical center, a parallel tuned circuit of inductance and capacitance connected between said anodes, and means coupled to a point on said inductance intermediate its ends for modulating the oscillations produced by said electron discharge devices.

5. A system in accordance with claim 3, including a grounded metallic tube placed about said linear element to prevent undesired radiation therefrom.

NILS E. LINDENBLAD.

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