US2193491A - Oscillation generator and frequency multiplier - Google Patents

Description

March 12, 1940. J. REINAR'rz I OSCILLATION GENERATOR AND FREQUENCY MULTIPLIER Filed April 23, 1937 @ggf/ff 605 Cy m M m SCREE/VGR/D POTENTIAL HARM/V/C FREQUENCY TUN/N6 HARMON/C E. FREOUENCYOl/TPUT |NVENTOR JOHN L. ENRTZ E /l/WM/ ATTORNEY Patented Mar. 12, 1940 r v v ,l i

UNITED STATES PATENT 'OFFICE OSCILLATION GENERATOR AND FREQUENCY MULTIPLIER.

.lohn L. Reinartz, Manchester, Conn., assigner to Radio Corporation of America, a corporation of Delaware Application April 23, 1937, Serial No. 138,508 4 Claims. (Cl. Z50-36) This invention relates to oscillation generator anda frequency multiplier stage, each stage corn-Ky and frequency multiplier circuit arrangements. prising an electron discharge tube,

Many circuit arrangements have been designed Fig. 2 sho-ws a modication of the second or in the past with the object o-f producing oscilfrequency multiplier stage, and y 5 lations at multiple frequencies of the funda- Fig. 3 shows still another modification in which 5` mental frequency generator, but among the dethe two stages of oscillation generation and frefects'and deficiencies of such arrange-ments it quency multiplication are suitably coordinated has been found that either these devices pro with but lone electron discharge tube of the twin duce output energy of a very low Value or else triode type.

the arrangement has been found lacking stability. Referring to Fig. l, I show an electron dis- :l0

Furthermore, if it is attempted to multiply the charge tube I preferably of the pentode type fundamental frequency so as to obtain one of the in which are a, cathode 2, a control grid 3, a higher harmonics, that is, above the third or screen grid 4, a suppressor grid 5, and an anode fourth harmonic, the difficulty of maintaining 6. The input lcircuit for this tube includes a grid an exact ratio between the output and the funleak resistor 1 and a radio frequency choke 3 15 damental frequency of the generator is very in circuit between the control grid 3 and ground. much increased. The cathode 2 is coupled to ground by means It is among the objects of my invention to of a capacitor S which may, if desired, be made provide a circuit arrangement including a funadjustable. Furthermore, the capacitor 9 and damental frequency oscillation generator and a the choke 8 in combination form a tank circuit 20 frequency multiplier such that output energy of which may be tuned to one-half of the fundaconsiderable amplitude may be obtained even mental frequency of the oscillations to be genwhen this output energy is multiplied to one of erated in the tube l. This fundamental frethe higher harmonics of the fundamental frequency is the frequency at which a piezo-electric quency. element I0 is adapted to vibrate. The element 25 As a result of my experiments it has been I is connected in shunt with the resistive and` proven that the tenth harmonic of the frequency reactive elements l and 8 respectively. of a generator having a piezo-electric crystal The tube I has its screen grid ll biased at a control may readily be obtained where only two suitable positive potential with respect to the electron discharge tubes are employed. In carcathodeY 2, this biasing being provided bymeans 30 rying out my, invention I was able to produce of a potentiometer II across the positive and the aforesaid tenth harmonic with a circuit arnegative terminals of a suitable direct current rangement which delivered as much as 10 watts source, as indicated by the plus and minus signs. of this harmonic frequency. This was done with- The anode I5 derives positive potential from this out exceeding the normal plate dissipation. source, the connection to the anode being made 35 It may readily be seen that the circuit arrangethrough the primary coil' I2 which forms with ment which I am about to` describe has considthe capacitor I3 a tank circuit tuned to the funerable utility in short Wave radio apparatus. If, damental frequency of the generator. A by-pass forqexample, a piezo-electric crystal were to be condenser I4 is preferably connected between the 40 employed having a frequency rating of, say, 3.75 screen grid lead and ground. Another oy-pass 40 megacycles (which corresponds to a wave length condenser I5 forms a coupling ConnectOn beof 80 meters), the tenth harmonic 0f this fretween the positive side of the'D. C. source and quency would be suitable as a carrier wave of ground- The negative Side 0f this SCWO@ is 0f 37.5 megacycles, or 8 meters. This same crystal Course groupdedis also likely to prove useful in a circuit in which The? Cuult *auth-gement tuus far decnbed 45 the sixteenth harmonic would be developed and cglsggrll ltsssclajllteenetr l'llavmlt 1 c as eve op a 1g Whle the mltrequey Ini ths bena 5 frequency, the constancy of` which is controlled meferwa've a 1 a W e a no a' requmcy by the piezo-electric device Iii. of 60 megacycles.

i The anode 5 of the Atube I is coupled by means 50 My invention Wlll now be descrlbed 1n detail, of a Capacitor gg to the control grid n of an refel'elle being made t0 the accompanying dlaW' electron discharge tube I8 in a secondvstage of ing in which I I the circuit arrangement. This second stage Figure 1 ShOWS a typical Circuit arrangement serves as a frequency multiplier. The input cirhaving a fundamental frequency generator stage cuit for the tube I8 includes a radio frequency mi` choke I9 in series with a grid leak resistor 20,

these two elements being connected between the grid I'I and the grounded cathode 2 I. The anode 22 is fed with current from the positive side of the direct current source through the secondary transformer winding 23. This secondary winding forms with the adjustable capacitor 2li a tank circuit tuned to a desired harmonic frequency of the fundamental frequency generated in the tube I. The coupling between the primary I2 and the secondary 23 is preferably made adjustable.

Output energy at the desired harmonic frequency is taken olf through a blocking condenser 25 whence it is carried to any suitable utilization device, not shown.

In order to appreciate the novel features of my invention attention should` be directed to the coupling arrangement between the output circuits of the two tubes.` This coupling between the primary winding I2 and the secondary winding 23 provides a mode of operation which has an analogy in the swinging of two pendulums, one at a fundamental frequency and the other at a frequency harmonically related thereto. The adjustment is such that the slow pendulum gives an impulse to the fast pendulum as often as their respective oscillations are in phase. Power output from the fast pendulum can be obtained at any harmonic rate. It will thus be seen that the second stage of my circuit arrangement is enabled to deliver` considerably more power than would otherwise be the case merely by virtue of the boosting effect of the output energy from the fundamental. frequency generator impressed across the interccupling transformer. This desirable result is only obtained, however, when the proper phase relationship exists between the transformer coupling and the coupling between the anode 6 of the first stage and the control grid Il of the second stage, that is, through the capacitor IS.

It has been observed that in the operation of this circuit the disconnection of the piezo-electric device causes oscillations to cease both in the fundamental frequency generator and in the frequency multiplier stage.

Referring to Fig. 2, I show the substitution of a screen grid tube "it for the triode tube I8 of Fig. l. It will be seen that this screen grid tube is connected to the portion of the circuit lying to the left of the dot and dash line a--a in the same manner as has been heretofore described with respect to the tube I8. It only nee-d be mentioned here, therefore, that the screen grid electrode 2l is supplied with a suitable positive potential with respect to the cathode 2l and that preferably the screen grid should be provided with a lay-pass condenser 25 constituting a radio frequency path to ground. In other respects the operation of the circuit arrangement shown in Fig. 2 will be fully appreciated from the foregoing description of Fig. l.

Referring to Fig. 3, I show a twin triode electron discharge tube 35 having a common cathode 3l, a grid 32 and an anode 33 in one triode portion, and a grid Sil, an anode 35 in the other triode portion. Considering the electrodes 35, 32, 33, it may be seen that these are connected to input and output circuits respectively in the same manner as is shown in Fig. 1 with respect to the tube i, that is to say, there is a grid leak resistor 'I connected between the grid 32 and the cathode 3i. There is also a piezo-electric device I connected between the grid 32 and ground. Furthermore, there is an adjustable capacitor 9 forming with the choke 8 a tank circuit tuned to one half of the fundamental frequency of the oscillation generator and of the piezo-electric device I0, this tank circuit being connected between the cathode 3i and ground. The anode Bil is connected to a positive d-c potential source through the primary I2 which forms with the adjustable capacitor E3 a suitable tank circuit tuned to the fundamental frequency. Referring to the electrodes 3I, 34, 35, it will be seen that these are connected to input and output circuits of a second stage, that is, a frequency multiplier stage, in the same manner as is shown for the tube I8 in Fig. l. Thus. the grid leak resistor is and the choke 2li are provided in the input circuit. The anode 35 is supplied with d-c positive potential through the transformer secondary 23, which secondary forms with the capacitor 24 a suitable tank circuit tuned to the desired harmonic frequency. The by-pass condenser 25 permits harmonic frequency energy to be taken olf and lead to any suitable utilization device. The operation of the circuit arrangement of Fig. 3 will now be clearly understood from what has been said with respect to Fig. 1.

In connection with a specic embodiment of my invention as shown in Fig. l, and as has been found to be suitable for generating a fundamental frequency of 3.55 niegacycles and where the eighth harmonic thereof or 28.4 megacycles was developed in the output circuit of the multiplier stage, the following values have been found to be suitable:

In the input circuit of the tube i the grid leak had a value of 5,000 ohms. The choke in series therewith had a value of 1GO microhenrys. The capacitor had a value of 100 micromicrofarads.

In the input circuit for the multiplier stage the grid leak resistor had a value of 50,000 ohms. The radio frequency choke in series therewith was of such value as to substantially prevent the leakage of high frequency energy to ground. The power output from the frequency mutilplier stage was in the neighborhood of 1I) watts when this stage was tuned to the eighth harmonic. The frequency thus delivered was 28.4 megacycles.

It will be understood that the circuit arrangements as herein shown and described are merely illustrative of numerous circuit arrangements of a general type coming within the scope of my invention.

I claim:

l. An oscillation generator and frequency multiplier comprising an electron discharge tube circuit arrangement constituted by two stages each having an input portion including a control grid, an. output portion including an anode, and a cathode system common to both portions inthe two stages, a source of direct current operating potentials suitably connected to said input and output portions, a tuned resonant circuit connected between the cathode system and the grounded negative terminal of said source, a piezo-electric device lconnected between the control grid of the rst stage and ground, a grid leak resistor connected between each control grid and the cathode system, a reactance in series with that one of said resistors which is in the second stage, two resonant circuits having adjustably intercoupled inductances and adjust ble capacitors, one of said resonant circuits being in the output portion of the first stage and the other in the output portion of the second stage, a capacitor coupling the anode of the rst stage to the control grid of the second stage, means for so adjusting the two resonant circuits of the input and output portions in the first stage that oscillations are generated at a fundamental frequency under control of said piezo-electric device, and means for so adjusting the resonant circuit of the output portion in the second stage i that oscillations are generated therein at a harmonic of said fundamental frequency.

2. A device according to claim 1 and further characterized in that there is but one electron discharge tube of the twin triode type in said circuit arrangement.

3. A two-stage electron discharge tube circuit arrangement comprising tuned input and output circuits for the first stage and a tuned output circuit for the second stage, the first stage constituting an, oscillation generator and the second stage a frequency multiplier, a piezo-electric device for controlling the fundamental frequency of the oscillations" generated, a tank circuit resonant to one half of said fundamental frequency connected in series with said piezo-electric device in the input circuit of said first stage, a grid leak resistor in shunt with said series connection, ca-

pacitive coupling means between the output circuit of the first stage and the input circuit of the second stage, and inductive coupling means between the output circuits of the two stages, said output circuits being tuned to different harrnonically related frequencies.

4. A circuit arrangement having a single electron discharge tube the cathode of which in combination with a first grid and a first anode constitute oscillation generatorelectrodes and the same cathode in combination with a second grid and a second anode constitute frequency multiplier electrodes, a tuned circuit and a piezo-electric device serially disposed in an input connection between the cathode and first grid, said tuned circuit being resonant to one half ther natural oscillation frequency of said piezo-electric device, inductively intercoupled output circuits connected from the cathode to the two anodes respectively, said output circuits being tuned to different harmonically related frequencies one of which is substantially the same as said frequency of the piezo-electric device, and capacitive coupling means connected between said rst anode and said second grid.

JOHN L. REINARTZ.

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