US2329069A - Space discharge type harmonic generator - Google Patents

Description

Sept. 7, 1943. J. MARKOWITZ 2,329,069

SPACE DISCHARGE TYPE HARMONIC GENERATOR Filed March 31, 1942 yum/11m? Patented Sept. 7, 1943 OFFICE :sPAoE mscnAnoE: TYPE HARMONIC VGENERATOR Jerome Markowitz, Allentown, Pa. Application'March 31, 1942, Serial No. 436,946

3 Claims.- (01. 250--36) This invention relates to ocillating space discharge devices and has particular reference to their use as harmonic generators and for. the simultaneous production of many different frequencies.

One object of the invention is to provide an improved generator capable of oscillating at a.

number of related frequencies atthe same time. Another object of the invention is to provide a, simple space discharge type oscillation generat'or which will produce a considerable amount of output oscillation energy at harmonic frequencies far removed from the fundemental as for instance the 20th or even higher harmonics. Another object of the invention is to provide an oscillation generator which will efficiently produce output oscillating energy simultaneously at a series of related frequencies and without the use of external filterfor wavetrap circuits.

Another object of the invention is the simultaneous production of a number of related frequencies with equal ease at either audio or radio frequency. 7 Other objects and advantages of the invention will become apparent as the specification proceeds. Y With the aforesaid objects in View, the invention consists in the novel combinations and arrangements of parts hereinafter described in their preferred embodimenta'pointed out in the sub'joined claims, and illustrated in the annexed drawing. wherein like parts are designated by the same reference characters throughout the figure.

'In the drawing:

The figure shows) a space discharge oscillation generator embodying the harmonic generating feature of the invention.

The advantages of theinvention as here outlined are'best realized when all of its features and instrumentalities are combined in one and the same structure, but'usefuldevices may be produced embodying less thanthe whole.

It Will be obvious to those skilled in the art to which the invention appertains, that the same may be incorporated in several different constructions. The accompanying drawing, therefore, is submitted merely as showing the preferred exemplification of the invention.

Generally "described the invention provides a harmonic generator consisting of a space discharge device oscillating at a given fundamental frequency and a second space discharge device coupled to it which produces output oscillating energy at a harmonic frequency or simultaneously at a number of harmonic frequencies depending upon certain circuit constants.

The fundamental frequency could more aptly be termed, a difference frequency as (the differential betweenfrequencies of a series of resultant harmonics would be determined naturally by that of the fundamental. The oscillator for producing this difference frequency consists of a space discharge device in combination with components which may form the circuit .of a Hartley. The space'discharge device may be of the indirectly heated cathode type. Connected to the grid is an inductance. The cathode is connected to an intermediate point on this inductance coil. Plate voltage to the oscillator is applied through a second inductance. This inductance is peaked preferably at a lower frequency than the difference frequency. Output oscillatory energy is obtained from the grid end of the inductance and is coupled to the control grid of a second space discharge device. This space discharge device consists of a cathode, anode, control grid and a. secondary grid. A high grid bias is applied to this space discharge device in any convenient manner. A positive potential is applied to the second grid. This potential is derived from the plate of. the difference frequency oscillator and by virtue of this fact this potential varies in accordance with the frequency of the differential oscillator. In other words the secondary grid may be considered to be modulatedat the difference frequency. The anode of the second space discharge device is alsomodulated at the'difi'erence frequency by voltage secured from the anode of the difference frequency oscillator. However this voltage is ap,-' plied thru an inductance which is tuned to the desired harmonic frequency. If a sequence of several of the harmonic frequencies is desired this inductance is designed to have a fiat resonance peak. It is possible to efficiently secure I relatively large amounts of oscillating energy simultaneously at a number of harmonics as for instance the 20th to the 30th inclusive. Referring in detail to the drawing: The figure denotes a preferred embodiment-of the invention. The same may include a space discharge device l including a cathode, anode, heater and grid, Connected to the grid 4 is a usual bias combinationconsisting of. parallel connected condenser I and resistor B. One end of an inductance 8 is connected to the grid .4 thru the aforementioned bias combination. The cathode 3 of the space discharge device is connected to an intermediate point on the inan inductance l2.

ductance 8 as shown at point iii. The remaining terminal of inductance 8 is connected to a common ground as shown at 23. The heater terminals X are connected to an appropriate source of current Y. Plate voltage for anode is obtained from a source of potential ll thru The second space discharge device l3 includes a cathode, anode, control grid, a secondary grid and a heater. The heater terminals X are connected to an appropriate source of current Y. The cathode I5 is connected to the common ground as shown. The control grid [4 is biased by a resistor 2| connected between said grid and ground. This grid is excited by an oscillating current which is generated by space discharge device I. The coupling is performed by a condenser 22 connected between grids 4 and Hi. The secondary grid I! is modulated by an oscillating potential which is derived from the anode 5 of space discharge device I. An inductance I9 is connected between the anode l8 and the secondary grid I! of space discharge device l3. A tuning condenser may be connected in parallel with this inductance. A tuning condenser 9 may also be connected in parallel with inductance 8. Harmonic output oscillation energy may be obtained from the space discharge device l3 by means of a line 24 connected to a load 25 which may be returned to ground as shown. Condenser 28 is a small by-pass to the common ground which prevents the harmonic oscillating energy from leaking back thru inductance l2. The size of condenser 28 is such that it offers a low impedance path to energy of the harmonic frequency but high impedance to oscillating energy of the fundamental frequency.

A typical example of the operation of the invention would be as follows: Space discharge device I is caused to oscillate at a frequency of 50,000 cycles by means of the proper value of inductance 8 and condenser 9. If one wished to cover at kilocycle intervals a band of a frequency of 800 to 1200 kilocycles it wouldbe necessary to generate the 16, 17, 18, 19, 20, 21, 22, 23 and 24th harmonics inclusive. In this case inductance l9 would be made broadly resonant, a feature which could be accomplished simply by using a relatively high resistance inductance I9. This inductance would be peaked at about 9'75 kilocycles. Variable tuning condensers 9 and 20 would be used to tune to an exact given fundamental frequency and harmonic. In cases where a single harmonic frequency is desired a high ratio of capacity to inductance is used, in accordance with the well known rule concerning inductance and capacity and. sharpness of resonance. Where a band of frequencies are to be covered the amount of capacity is reduced or it is omitted entirely.

I am aware of the fact that previously it was well known that high bias, high excitation and broadly tuned resonant circuits were conducive to the production of harmonics by space discharge repeating devices, however, in these circuits the harmonic energy and plate efficiency drops ofi rapidly as, the harmonic sequence progresses whereas with the present invention large amounts of harmonic energy can be secured with relatively good plate efliciency and without the use of extra filters or wavetrap circuits.

Having thus described my invention what I claim is:

1. A harmonic generator comprising a given frequency oscillator consisting of a space discharge device having a cathode, anode and grid, one end of an inductance connected to said control grid, an intermediate point of said inductance connected to said cathode and a connection from the other end of said inductance to the negative terminal of a source of anode potential and means for connecting the positive terminal of said anode potential source to said anode through an inductance whereby oscillations are produced, a second space discharge device having a cathode, anode, control grid and secondary grid and a coupling condenser connected between the control grids of the first and second mentioned space discharge devices, a connection from the anode of the first mentioned space discharge device to the secondary grid and also a connection from the anode of the first mentioned space discharge device to the anode of the second mentioned space discharge device thru an inductance whereby a harmonic series of oscillation energywill flow thru this coil whose frequencies will depend upon its inductance.

2. A harmonic generator comprising a given frequency oscillator consisting of a space discharge device having a cathode, anode and grid, an inductance connected between said anode and grid, a connection from said cathode to an intermediate point on said inductance, means for applying between said cathode and anode a voltage sufficient to cause oscillation and means for coupling output oscillating energy from the grid of the said space discharge device to the control grid of a second space discharge device having a cathode, anode, control grid and sec-.

ondary grid,'and means for supplying the secondary grid of said second space discharge device with a potential modulated at the oscillation frequency of said given frequency oscillator and an inductive means connected between the anode and secondary grid of said second space discharge device whereby the potential applied to thesecondary grid will also be applied to the anode but through said'inductive means and whereby a harmonic or series of harmonic frequencies will be generated whose frequency or frequencies will be dependent on the inductance of said inductive means.

3. A harmonic generator comprising a given frequency oscillator including a space discharge device having a cathode, anode, and grid and a space discharge repeater device, said repeater device having a cathode, anode, control grid and a secondary grid, means for exciting the control grid of said repeater device with oscillating energy derived from the grid of said given frequency oscillator space discharge device, and means for applying to the secondary grid of said repeater device a modulated potential varied by the given frequency oscillator and an inductance means tuned to a harmonic of the given frequency oscillator-connected between the anode and secondary grid of said repeaterdevice where by oscillating energy will be set up in said inductance means whose frequency-will be harmonic to, that of the given frequency oscillator;

JEROME MARKOWITZ.

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