US2018318A - System for transmitting electro-radiant energy - Google Patents

Description

Oct. 22, 1935. E. s. PURINGTQN 2,018,318

SYSTEM FOR TRANSMITTING ELECTRQ RADIANT ENERGY A Original Filed Dec. 23, 1925 2 Sheets-Sheet l INVENTOR ELUSON S. P RlNGTON ATTORNEY Oct. 22, 1935.

E. s. PURINGTQN SYSTEM FOR TRANSMITTING ELECTRO RADIANT ENERGY 2 sheets sheet 2 Original Filed Dec. 23, 1925 "w r T INVENTOR ELUSON s PUNNGTON BY u)1/W A:ITO'RNEY Patented Oct. 22, 1935 UNITED STATES PATENT OFFICE SYSTEM FOR TRANSMITTING ELECTRO- RADIANT ENERGY Original application December 23, 1925, Serial No.

77,194. Divided and her 30, 1932,

5 Claims.

This invention is a division of application Serial No. 77,194, filed December 23, 1925, Patent No. 1,899,527, granted February 28, 1933, entitled System for transmitting electro-radiant energy.

This invention relates to radio transmission systems and particularly to an improved system 101' more efiicient transmission of radio signals.

The purpose oi this invention is to provide an efiicient transmission system for wireless signalling by coupling together in a new and improved manner two or more vacuum tubes, one or more of which may be caused to produce oscillations.

An object of this invention is to provide a simple arrangement for effecting the modulation 01' an oscillating system.

Another object of the invention is to prevent losses in a modulating audion tube employed to modulate the high frequency oscillations to be radiated of a transmission system.

Another object is to provide an efilcient feedback circuit for a vacuum tube oscillator the adjustment of which is not substantiallyafifected by nor does it affect the constants of the oscillatory circuit which determines the frequency of the current produced by the oscillator.

Another object of this invention is to provide a suitable circuit for by-passing any high frequency currents to keep them from the modulator tube.

Another object of the invention is to provide means for obtaining proper feedback voltage i'or the grid of a space discharge device independent of the frequency and constants of the oscillatory circuit over a considerable range.

Another object of this invention is to couple two oscillating circuits together in such a way that the frequency of one may be changed without atfecting the other.

Another object of this invention is to provide means whereby one of the oscillators may be of the mechanical type.

Still another object of the invention is the construction of an oscillation circuit employing a mechanical oscillator in which all that need be done to change the frequency generated is to replace the mechanical oscillator with one 01' the proper frequency characteristics.

Still another object is to apply a radio oscillating device as a driver for a mechanical oscillator.

Further objects will appear from consideration of the specification and drawings in the latter of which:-

Fig. 1 is a diagram of the connections involved in an embodiment of my invention.

Fig. 2 shows the invention as used to drive a this application Septem- Serial No. 635,492

mechanical oscillator such as a tuning fork with a series connection.

Fig. 3 shows the same with a parallel connection.

Fig. 4 shows the same with a crystal oscillator.

The embodiment of this invention illustrated in 5 Fig. 1 shows a low frequency or modulating oscillator l and a high frequency or radio oscillator I 2 connected by circuits so that the high frequency oscillations produced by the radio oscillator are modulated by the low frequency oscillations.

The oscillating modulator triode i has connected across its anode and cathode through a condenser I on the anode side an oscillatory circuit 2-3. The oscillating circuit may be keyed by means of a. key 5 connected in circuit with a 15 condenser 6. The Irequency of oscillations produced by tube I is determined chiefly by the oscillatory circuit 2, 3 and the keying condenser 6. Consequently the frequency 01'. oscillation is altered by closure of the key and by this alteration l0 signalling is efiected. Instead of the keying being done by changing the capacitance of the oscillatory circuit, it may be adapted to vary the inductance of the oscillatory circuit. The oscillatory circuit is connected to the cathode l in the 35 usual manner.

The plate current is supplied by a direct current generator 8 through an inductive impedance or choker coil 9. The generator is shunted by a condenser H? which will allow icy-passing of any alternating currents which may leak through the choke coil 9.

Grid excitation is obtained by coupling in a proper manner an inductance I 5 connected between the grid and cathode of tube l to the in- 35 ductance 2 of the oscillatory circuit 2-3. A grid leak is employed as shown in a well known manner.

The radio oscillator oi the system consists of a vacuum tube l2, the plate and filament 0! which are connected to the direct current source 8 substantially in parallel with the plate and filament of the tube I. The radio oscillator includes an oscillatory circuit which consists of an inductance l3 to which is variably connected the plate of the tube I2 through a condenser H. The antenna I6 is also tapped variably to inductance [3 through a condenser l5, and the capacity to the ground indicated by H completes the oscillatory circuit.

The oscillatory circuit 2-3 of the modulating 50 oscillatoris connected to the anode and cathode terminals 01 the radio oscillator l2, thereby placing the two tubes in parallel relation. Connections to the anode oi the tube l2 are made through condenser I l and inductance I8.

' crystal as the case may The circuit 4-3-6 is so constructed as to provide a capacitance path which will by-pass any and thus prevent them from being impressed across the modulating oscillator I. By so doing,

cited, as is done in many instances, it would not be possible to by-pass all of the high frequency currents, as a condenser large enough for this purpose could not be used without imposing aconsiderable capacitance load on the modulator,

thereby impairing its efficiency.

As shown, grid excitation and feedback for the radio oscillator tube I2 is obtained by coupling the grid to the antenna inductance 13 through a transformer, the primary of which is in parallel relation to inductance l3. The correct adjustment of the feedback is dependent only upon the frequency at which the oscillatory circuit is to operate, so that in adjusting the transmitter to an antenna of unknown constants, the plate and wave length taps only need to be varied to produce the correct adjustment. The usual grid leak is also employed in connection with this tube.

If secrecy is desired in the transmission and reception of signals by this systennthe low frequency must be of an inaudible frequency and the high frequency oscillations may be wobbled in frequency as by cyclically inserting condenser 23 in the oscillatory circuit in conjunction with keying thelow frequency oscillations, making it imperative to use a double detector system to receive the signals. A receiver suitable for receiving under these conditions is shown in patent to Hammond No. 1,540,881, June 9, 1925..

In the operation of this system, both tubes are set to oscillating, the radio oscillatory tube at a high frequency and the modulating oscillator tube at a low frequency which latter frequency will yary the amplitude of the oscillations of the high frequency waves. The keying of the modulating oscillatory circuit changes the frequency of modulation for signalling purposes.

It can be seen that by the arrangement shown in the drawings it is possible by connecting a mechanical oscillation device such as a tuning fork or a piezo-electric crystal in place of the cs- 1) and coupling the circuit to the grid circuit that an oscillation generatorcircuit will result which is capable of generating oscillations of a frequency dependent over a considerable range mechanical oscillator device only so that all that need be done inorder to change the frequency to upon the frequency of the be generated is to change the tuning fork or the be. Putting it another way, there-will be a negative resistance developed across the winding 2 or across the anode cathode of the tube such that if a: mechanical oscillator is placed across either, of said points energy of a frequency equal to the frequency of the mechanical'oscillator-will be generated. Thus, the same principles of coupling'the grid for the purpose of excitation and feedback by means-of the transformer connection can be applied to series or parallel circuits to drivers of mechanical oscillators. Three such arrangements are shown in Figs. 2 to 4. V V

More particularly in Fig. 2 there is shown.

.means for electrically controlling a thermionic radio frequency currents produced by the tube I2 valve by means of a tuning fork. The thermionic device 30 includes in its plate circuit the coil 3| of the drive of the tuning fork 32 and the high potential source 33 and the {plate circuit is shunted by the circuit composed of the condenser 5 34 and inductance 35, the latter of which is inductively coupled to the inductance 33 in the grid circuit of said thermionic device. The plate current serves to actuate the tuning fork ,by means of the electro-magnet formed by the inductance 10 3| and the core 38 as shown, and the oscillating current existing in this circuit is fed back to the grid circuit by means of the inductive coupling between the inductances 35 and 33. Should the oscillations existing in the plate circuit and con- 15 sequently in the electro-magnet be opposed to the natural motion of the tuning fork, a second electro-motive-force will be generated which will in passing through the condenser 34 influence the inductance 35in such a manner as to impress a 20 potential tance 40 and the high potential source 33. The 30.

grid circuit includes the grid and the inductance 36. In shunt with the plate circuit is a second plate circuit including a condenser 34 and the inductance 35, the latter of which is inductively 7 related to the grid inductance 36. In parallel with 35 the inductance 35 is the electro-magnetic winding 43 of the tuning fork 32. The vibration of the tuning fork will impress upon the electro-magnetic winding a frequency which is the same as the natural frequency of the tuning fork and this will cause a current to flow through the inductance 35 which will cause a current to be impressed upon the grid inductance 36 in such a manner as to cause the plate current to vary through the action of the device 30 in accordance with the frequency of the tuning fork. The plate voltage will be transferred by means of a condenser 34 to the tuning fork inductance 43 and will serve to augment the current in the tuning fork circuit provided it is in phase therewith. I In case the natural fre- 5 quency of the oscillatory circuit is not the same as the natural frequency of the tuning fork, the current generated by the latter will buck that generated by the former and the phase. of the input of the will be shifted until the output of the said device will aid the electro-motive-force generated by the tuning fork. .Thus, it can be seen that the tuning fork can be made to control the frequency of the thermionicdevice 30. larly it may be seen that in either Fig. 2 or 3, if the current produced by the tuning fork 32 and the current produced by the thermionic device 30 are in phase an oscillatory E. M. F. will be furnished to the tuning serve to keep the fork 32 in motion.

Referring now more particularly to Fig. 4 there is shown a system for controlling the oscillation of the thermionic circuit by means of a piezo crystal.

7 The connections of the thermionic device are the 70 thermionic device 30 Simiw fork inductance which will frequency of the thermionic oscillator is the same as that of the tuning fork in Fig. 3. In other words, as long as the electro-motive-force in the inductance 35 caused by the transfer of ener y from the plate circuit through the condenser 34 is in phase with the electro-motive-iorce generated by the vibration of the piezo crystal, the frequency of the impulses impressed on the grid of the thermionic device 30 will remain constant.

It is evident from what has preceded that the frequency generated by any of the three circuits is for a considerable range dependent only upon the frequency constants of the mechanical oscillation so that should a different frequency be required all that need be done when my system is utilized is to change the tuning fork or the piezo crystal. This is a distinct advantage over the systems now in use with plug in coils since in such systems the tickler coil must be changed as well as the tuning coil.

The invention is not limited to the above uses which are described merely as illustrations, but on the other hand may be utilized in many ways as will be defined in the appended claims.

I claim:

1. An oscillation generator comprising an electronic oscillator having an anode, a. cathode and a grid, a circuit connection between said anode and cathode including a choke coil and a source of space current, a second circuit connected between said anode and cathode including a condenser and a coil, a circuit for connecting the grid and cathode including a coil, said two coils being inductively related so as to effectively couple said second circuit and said last named circuit, and a circuit including resonator driving means shunted across said first coil, a resonator adapted to be driven thereby and. to induce electrical actions in said circuits ior determining the frequency of the produced oscillations.

2. An oscillation generator comprising an electronic tube having an anode, a cathode and a grid, a circuit connection between said anode and cathode including a source of space current, a second circuit connected between said anode and cathode including a coupling coil, a circuit for connecting the grid and cathode including a coiL'said two coils being inductively related so as to effectively couple said second circuit and said last named circuit, a resonator driving means in one of said first two named circuits and shunted across at least the first named coil, a resonator adapted to be driven thereby and to induce electrical actions in said circuits for determining the frequency of the produced oscillations.

3. In a circuit arrangement for generating oscillations 01' any frequency within predetermined limits the frequency of the generated oscillations 5 being determined solely by the characteristics of a resonator device, an electronic tube including an anode, a cathode and a grid electrode, a connection between the grid electrode and cathode including the secondary winding of a coupling 10 transformer, a connection between the anode and cathode of said tube including a condenser and the primary winding of said coupling transformer in series, a resonator device and driving means therefor and a connection across said condenser 15 and primary winding including said resonator driving means and a source of space current for said tube in series.

4. In a circuit arrangement for generating oscillations of any frequency within a band of 20 frequencies of substantial width, and wherein the frequency of the generated oscillations is dependent only upon the irequency characteristics of a resonator device, an electronic tube including an anode, a cathode and a grid electrode, a 25 connection between the grid electrode and cathode including the secondary winding of a coupling transformer, a connection between the anode and cathode of said tube including a condenser and the primary winding of said coupling 30 transformer in series, a resonator device and driving means therefor, a connection across said condenser and primary winding including a source of space current for said tube and a connection across said primary winding including said res- 35 onator driving means.

5. In a circuit arrangement for generating oscillations of any frequency within predetermined limits, the frequency of the generated oscillations being determined solely by the characteristics of so a resonator device, an electronic tube including an anode, a cathode and a grid electrode, a connection between the grid electrode and the oathode including one of the windings of a transformer, a connection between the anode and 45 cathode of said tube including a condenser and the other winding of the transformer in series,

a resonator device and driving means therefor and a connection across said condenser and the first mentioned winding including said resonator 50 driving means and a source of space current for said tube in series.

ELLISON S. PURINGTON.

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