US2055881A - Electron coupled generator and frequency multiplier - Google Patents

Description

Sept. 29, 1936. J. L. REINARTZ 2,055,331

ELECTRON COUPLED GENERATOR AND FREQUENCY MULTIPLIER Filed NOV. 14, 1953 500862- OF 750 K Cl/fifiA-WT I 11 2 60m. A 6

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sol/Res 0F 750V 50080, 0; 1%; Q (ax/v5? /77 40/77 7 .5 INVENTOR JOHN L. REINARTZ I; I 4H i Kg Patented Sept. 29, 1936 ELECTRON COUPLED GENERATOR AND FREQUENCY MULTIPLIER John L. Reinartz, Manchester, Conn, assignor to Radio Corporation of America, a corporation of Delaware Application November 14, 1933, Serial No. 697,909

5 Claims.

The present invention relates to a novel method of and means for producing oscillations of high frequency and to a novel method of and means for increasing the frequency of the oscillations produced :if desired.

More in detail, the present invention relates to a novel high frequency generator of the electron type :inwhich the output circuit is coupledto the input circuit by the electron stream only, and to a novel thermionic frequency multiplier and amplifier of the electron coupled type which may be coupled ina novel manner to the novel generator of the present invention to increase the frequency and amplitude of the oscillations generated and supply the same to additional amplifiers or to any lcad-circuit.

The novel features of my invention have been pointed out with particularity in the claims 'ap pended hereto.

The invention will be better understood from the vfollowing detailed description thereof and therefrom when read in connection with the drawing, .in which:

Figure 1 is a wiring diagram of an oscillation generator arranged inaccordance with the present invention;

:Figure '2 is .a circuit arrangement of the oscillation generator of Figure 1 :connected with a thermionic amplifier and frequency multiplier arranged in accordance with the present invention; while,

Figure 3 iSaB. detailed illustration of the manner .in which certain of the inductances used in the circuit :of the present invention may be wound; and

Figure '4 is a modified circuit arrangement.

To-obviate the necessity for a numberof stages when it isdesired to double or quadruple the orig- .inal-frequency='of a master oscillator, I propose to use any screen grid tube in a novel circuit. The tube, when connected as :an oscillator, will function with maxi-mum screeningwhich is necessary at. the fundamental frequencytor the first-or second harmonic of thefundamental frequency. In accordance with the present invention this is :ac- .cornplished :by arranging the circuit so that the filament-is at a higher radio frequency potential thanzthersoreenzgrid. The control grid is included as part of the filament radio frequency circuit and-is'at a'higher radio frequency potential than the filament. The plate is shielded-by the :screen grid and will operate at the fundamental frequency 7 that the grid is being operated at=or at the second,

f 5 or third,

5 3 l or fourth,

harmonic, as desired, without effect on theoperation of the control grid'circuit. The value of the E5 coupling condenser 2| determines in part the in:- tensityof the oscillations generated. The condenser 8 aids in balancing the voltage swing across the primary and secondary coils of the transformer 4. V j 7 The general connections are shown in Figure ,1. In order that the filament K may beopera-ted at a higher potential than thescreen grid-t2,- which-is at ground radio frequency potential, the tuning system coil 4 for the control grid filament and .25 filament heating circuit is wound with :two wires of such asize that the voltage drop through these wires for the-filament current which flows through these wires will not exceed 0.2 volt. In general this wire size need-not be larger than number 14 30 B&S gauge. A convenient method of winding the coil 4 and at the same time allowing it to be selfsupporting is to wind the 'coilthe basket weave way. A loop is made at the point where the filament connections are to be made. loop is at the first one-third of the total winding turns, '21 total turns are required for the .80 meter band, with a tap at the seventh turn, ten total turns for the 40 meter band witha tap at the third turn. I e40 drive a tube or tubes As a master oscillator to as class C amplifiers up to l00 watts input a single screen grid type tube (865) is required when it is desiredto double the fundamental frequency only. In this case the output electrode (anode) of the oscillation generator of Figure 1 may be coupled toan amplifier of the class C type in any manner. The amplifier may operate at a fundamental fre- "quency'ofxiw meters or. of 4.0 meters.

If it is desired to quadruple the frequency from,

This tap 01-335 7 say, the 80 meter band to the 20 meter band, I use a second 865 as a screen grid radio frequency amplifier for the triple 20 meter band in order that sufficient excitation may be available for the 100 watt class C tube or tubes. Such an arrangement has been shown in Figure 2, in which the (electron coupled) oscillator of Figure 1 is connected by way of a coupling capacity to an additional frequency multiplying and amplifying stage. The input I 0 of this stage may be tuned to 40 or 20 meters. If it is desirable to again double the frequency (20 meters) at the second 865 to 10 meters it is best to connect the second 865 as an electron coupled oscillator which is excited by the first oscillator and then give the second tube a little additional excitation in addition to that which it gets from the first oscillator (865) by the use of feed-back capacity 2| of the order of 10 to 15 micro-microfarad. The circuit connections for this arrangement are shown in Figure 2. In the second stage the inductances H] are wound and connected as pointed out in connection with Figure 1. The first stage may be as in Figure 1, except as otherwise indicated.

The capacity 2| connected between the control grid and the terminal of one of the windings 4 and the tuning capacity in the first stage may be in the orderof 100 micro-microfarads. This capacity provides excitation for the control grid electrode and insures the production of sustained oscillations of a constant frequency which is de termined by the inductances connected with said control grid and by the tuning capacity in parallel with said inductance. The second stage of Figure 2 may act as a frequency multiplier and amplifier and in this case is excited or driven by energizing its control grid by oscillations from the output electrode of the first stage. When a higher harmonic of the fundamental frequency 80, such as 10 meters, is desired in the output circuit of the second stage, a capacity 2| of less value and variable, connected between the inductances I0 and the control grid of the tube in the last stage, suffices to insure the excitation necessary in addition to the excitation from the first stage which produces the oscillations. This capacity may be adjusted to a value slightly less than that which would be required to insure sustained oscillations were the second stage not excited by a preceding stage. A variable capacity of the order of 5 to 15 micro-microfarads suifices at this point. Of course, if desired, the second stage can be caused to act by itself as an oscillation generator by increasing the value of this capacity. Under the latter circumstances oscillations will produce in the same manner in which they are produced in the first stage.

Any screen grid tube may be used as a crystal controlled tube in the electron stream coupling. When so used the filament is connected at the low radio frequency end of the total coil turns. The crystal is then connected between the control grid and the filament end of the coil, as shown in Figure 4.

In all cases the grid leak is connected to the number two wire of the two wire coil; the numher one wire is the wire to which the grid condenser is connected and to which the tuning condenser is connected. A by-passing condenser of .01 isconnected at the end of the total coil turns to make the two wires a single part of the radio frequency circuit. Such a condenser is also connected to the two coil wires at the beginning of the 0011 from each wireto the cen er p n t e filament transformer. A large by-pass condenser is connected between the center tap and the screen grid. The negative high potential is connected to the center tap and to ground.

Rated voltage is applied to the filament, the screen grid and the plate. The filament voltage is measured at the filament terminals at the socket, after passing through the two coil wires.

When a screen grid tube is used as an electron stream coupled stage greater output can be obtained than when used as a crystal controlled tube, its advantage being in the use as an electron coupled tube. It then acts as a frequency doubler, if so desired, as well as being an efficient buffer. The circuit is simple, no neutralization being required except at the final radio frequency amplifier connected with the output of the circuit of Figure 1 or Figure 2 if it is a triode.

The electron coupled stages operate efficiently and in a stable manner since the only coupling between the input electrodes and associated circuits and output electrodes and associated circuits is by way of the electron stream. Stability of operation is further enhanced by maintaining the screening electrode at low radio frequency potential.

In practice the tuning inductance in the several stages may be of the plug-in type so that the circuits may be readily changed to tune to the desired frequency. Of course, switching means cooperating with taps may be used to change the tune of the circuits.

Having thus described my invention and the operation thereof, what I claim is:

1. Means for producing radio frequency oscillations comprising, a thermionic tube of the screen grid type, a pair of parallel inductances, each inductance having one terminal connected to a different point on a source of heating current, a resistance connecting the other terminal of one of said inductances to the control grid of said tube, a capacitor connecting the free terminal of the other of said inductances to the control grid of said tube, the filament leads of said tube being connected each to its respective one of said inductances and at points thereon such as to include less than half of said inductances in the filament heating circuit, a tuned network in circuit between the anode and the cathode of said tube, and a circuit connected between the screen grid of said tube and the filament of said tube, the last said circuit having an impedance value such that radio frequency currents applied simultaneously to said filament and to said screen grid have a lesser voltage swing on the screen grid than on the filament.

2. An oscillation generator comprising, a thermionic tube having an anode, a cathode, a control grid and a screening grid electrode, a pair of parallel inductances, means for connecting adjacent terminals of said inductances to the control grid of said tube, means for connecting the free terminals of said inductances to different points on a source of heating potential, means maintaining said source of heating current at low radio frequency potential, means for connecting the cathode of said tube to points on said inductances such as to include less than half of said inductances in the cathode circuit whereby the control grid of said tube is at radio frequency potential greater than the radio frequency potential of the cathode of said tube, a load circuit coupled between the anode and cathode of said tube, said load circuit being uncoupled magnetically with respect to said inductances, and means for insuring stable operation of said tube includinga connection between the screen grid of said tube and a point on the cathode circuit of radio frequency potential lower than the radio frequency potential of the cathode of said tube.

3. Frequency multiplying means comprising, a thermionic tube having control grid, cathode, screen grid electrode and anode, a circuit for applying a fundamental frequency to be multiplied to said tube comprising a pair of adjacent wound inductances, a capacity connecting an end of one of said inductances to the control grid of said tube, a, resistance connecting the end of the other of said inductances to the control grid of said tube, a circuit connecting the free ends of said inductances to difierent points'on a source of cathode heating current maintained at a low radio frequency potential, a circuit connecting the screen grid electrode of said tube to said source of cathode heating current, a circuit con necting points on said inductances to the cathode of said tube whereby the cathode of said tube is maintained at a radio frequency potential intermediate the radio frequency potential of said control grid and said screen grid electrode, a circuit connected between the anode and cathode of said tube, and means for tuning said last named circuit to a harmonic of the fundamental frequency.

4. A circuit for energizing the filament and the control grid of a thermionic tube comprising, a pair of parallel inductances wound side by side, a resistance connecting the terminal of one of said inductances to the control grid of said tube, a capacitor connecting the terminal of the other of said inductances to the control grid of said tube, the filament of said tube being connected to points on said inductances, and a source of filament energizing current connected at different points to the other terminals of said inductances.

5. Wave producing means comprising, a thermionic tube having control grid, cathode, screen grid electrode and anode, a circuit comprising a pair of adjacent Wound inductances, a capacity connecting an end of one of said inductances to the control grid of said tube, a resistance connecting the end of the other of said inductances to the control grid of said tube, a circuit connecting the free ends of said inductances to different points on a source of cathode heating current, a circuit connecting the screen grid electrode of said tube to said last named circuit, a circuit connecting points on said inductances to the cathode of said tube whereby the cathode of said tube is maintained at a radio frequency potential intermediate the radio frequency potential of said control grid and said screen grid electrode, said capacity being adjustable to feed suificient excitation energy to said grid to insure the production of sustained oscillations in said circuit of a frequency determined in part by the circuit constants when said tube is to be used as an oscillation generator or to feed less excitation energy to said grid electrode when wave energy is applied to said circuit to be multiplied in frequency, a circuit connected between the anode and cathode of said tube, and means for tuning said last named circuit to the frequency of the oscillations generated or to a harmonic of the applied wave.

JOHN L. REINARTZ.

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