Sept. 17, 1935. A. H. TAYLOR 2,04,913 CIRCUIT FOR PRECISION CONTRO OF MASTER OSCILLATORS Filed Feb. 8, 1933 rvuorvov ALBERT H.TAYLOR &tkow, Patented Sept. 17, 1935 2014,913 UNITED STATES PATENT OFFICE 2,014,913 CIRCUIT FOR PRECISION CONTROL OF MASTER, CSCELLATORS Albert H. Taylor, Washington, D. C., assignor to Wired Radio, Inc., New York, N. Y., a corpora tion of Belaware Application February 8, 1933, Serial No. 655,829 4 Claims. (C. 250-36) My invention relates broadly to high frequency oscillation systems and more particularly to a screen grid electrode of the tetrode Oscillator and circuit for the precision control of master Oscil another of the taps at higher potential leading to lators in a high frequency OScillation System. the plate electrode. A high frequency inductance One of the objects of my invention is to pro system is connected in circuit between the control vide a simplified circuit for a high frequency grid and the anode. A pair of balancing con Oscillation system which is constructed to deliver densers is connected in series across the induc Oscillations of high frequency and efficiency. tance and a connection taken from a midpoint Another object of my invention is to provide between the condensers to a return circuit lead 0. a circuit arrangement for a high frequency OScil ing to the Cathode. Provision is made for con lator and amplifier System having a high degree necting a balance condenser between the Screen O of freedom from variation in frequency brought grid and any point in the coil system. Depend about by variations which may occur in plate ing on the internal constants of the particular voltages in the high frequency OScillation System. type of tube used, this point may be either above Still another object of my invention is to pro or below the neutral potential point on the coil vide a high frequency OScillator and power ann system. The purpose of the balance condenser is plifier circuit arrangement having relative sim to neutralize the electrical coupling between the plicity of adjustment by means of direct current anode and screen grid. One end of the coil sys meters in the plate and Screen circuit of the high tem is connected to the control grid and the other 20 frequency oscillation system. end through a stopping condenser to the anode. A further object of my invention is to provide These ends are opposite in potential. By adjust- 20 a circuit arrangement for utilizing the electrical ing with the balance condenser the radio fre coupling between the plate and Screen electrode quency potential of the Screen grid, the best free in an electron coupled oscillator. dom from reactions, due to tuning of the ampli A further object of my invention is to provide fier circuit may be obtained. This reaction may an arrangement of coupling System between an be reduced to a frequency change of only one or 25 oscillator and a power amplifier in which the two parts in 100,000-sometimes better. power amplifier has its input system selectively The next important feature in the circuit is connected either to the plate electrode of a the fact that it is so readily adjusted to guard 30 tetrode oscillator or to the Screen grid electrode against variations in the oscillator frequency of the tetrode oscillator for Securing maximum when the supply voltage is altered. Radio fre 30 efficiency in the transfer of energy from the os quency ammeters, not shown in the drawing are cillator to the power amplifier While maintain ordinarily Of course placed in Series with the ing the frequency of the transferred energy, anode and screen grid to determine the current constant. which each one draws, and it has been found Other and further objects of my invention re that When the direct current potentials of anode side in the improved circuit arrangement for the and Screen grid are so adjusted with respect to precision control of master oscillators as will be each other that the ratio of screen grid current set forth more fully in the Specification herein to anode current is about in the ratio of four 40 after following by reference to the accompany to five, the circuit is remarkably free from varia ing drawing which diagrammatically illustrates tions due to anode voltage alterations. The the circuit arrangement of my invention. changes of frequency due to anode voltage varia I have found the high frequency oscillator and tion of 50% are not more than one or two parts power amplifier System of my invention very in 100,000. 45 practical and stable in its operation. The syS Referring to the drawing in more detail, the tem has a high degree of ease of adjustment and tetrode oscillator is indicated by reference char has a high output efficiency. The high frequency acter , having cathode a, control grid ib, screen oscillator and power amplifier stages are consti grid c and anode d. The input circuit of the tuted by tetrodes. The grid of the power ampli tetrode oscillator is completed between control 50 fier may be excited either by a connection through grid b and cathode a through radio frequency a stopping condenser to the shield electrode of choke coil 2 and resistance 3. The cathode a is the tetrode oscillator or by a connection to the energized from any suitable source of potential as plate of the tetrode oscillator. A potentiometer represented generally at 4. The potential for connected across a Source of high potential is the screen grid ic and anode d is obtained from 55 the potential source indicated at 5, which is elec provided with taps, one of the taps leading to the trically connected to the potentiometer 6. A tap 55 2 2,014,913 7 of selected potential on potentiometer 6 con invention. The oscillator and power amplifier nects through radio frequency choke coil 8 to the System of my invention have relatively great Screen grid electrode c. A tap 9 of higher se freedom from frequency changes, often brought lected potential on potentiometer 6 connects about by variations in anode potentials. The cir through radio frequency choke coil 9 to the cuits allow relative simplicity of adjustment by anode d. The high frequency inductance sys means of direct current meters disposed in the ten which is connected with the tetrode is anode and Screen grid circuit. The oscillator shown at . The high frequency inductance and power amplifier circuit is so arranged that system has its terminal bridged by condensel's 2 the full realization of the benefits which accrue 0 and 4 electrically connected in Series. The mid from the proper adjustment of the potentials on 0 point 5 between condensers 2 and 4 is con the electrodes of the oscillator and power aimpli nected by lead 6 to the midtap connection 7 of fier tubes is obtained to insure minimum varia the cathode potential supply transformer 8 lead tions in frequency with voltage variation. The ing to the power amplifier tetrode 2. The lead natural order of potentials on the screen grid 9 which connects to lead f and midtap i also and anode electrodes of the oscillator and power provides a return path to the cathode - d. of the amplifier tubes is such that the condition for high tetrode f. The inductance system has the end energy and high stability is made to coincide. f a thereof connected through lead 2 to control While I have described my invention in one of grid b. The end f b of high frequency induc its preferred embodiments, I desire that it be 20 tance is connected through stopping condenser understood that modifications may be made and 20 22 to the anode d. A balancing condenser 23 is that I intend no limitations upon my invention connected between the Screen grid c and a se other than are imposed by the scope of the ap lected potential point 24 on the inductance if pended claims. What I claim as new and desire to secure by intermediate the ends a and b. The point 24 25 2 5 may be either above or below the neutral poten Letters Patent of the United States is as follows: tial point on the coil system depending upon the 1. A high frequency oscillator and power am internal constants of the particular type of tube plifier System comprising a tetrode including a used. The balance when adjusted, neutralizes Cathode, a control grid, a screen grid and an an the electrical coupling between the anode id and Ode, a high frequency circuit connected between 30 the Screen grid c. Said control grid and said cathode, a high fre 30 The power amplifier constituted by tetrode 2) quency inductance having one end thereof con includes cathode 20a, control grid 20b, screen nected with Said control grid and the other end grid. 20c and anode 20d. The Cathode 2d. is en thereof connected with said anode, a balancing ergized as heretofore stated through transformer Condenser, a tap on Said high frequency induc 8. Bypass condensers 25 and 26 are connected tance, a circuit extending from said tap through 3 5 acroSS the tWO parts of the Secondary Winding of Said balancing condenser to said screen grid, transformer 8. The midtap 7 of transformer means for Supplying relatively different poten 8 provides a return path for the anode circuit of tials to said Screen grid and said anode, a pair of the power amplifier 29 through lead 9. Source condensers disposed in series and connected 40 of potential 5 which Supplies anode voltage to the acroSS Said inductance, a tap extending from 40 oscillator tetrode 1 also supplies anode voltage to a central point between said condensers to said power amplifier 20.