US2111086A - Oscillation generator - Google Patents

Description

March 15, 193.8'.

Filed Nov; 2o, 1935 l D. BAsl'M,

QSCILLATION GENERATOR' /mf PEs/57mm: ,3 TEMPE/enn/,ef

CAoEFF//ENT.

Patented Mar. 15, i933 UNITED OSCILLATION GENERATOR Donald Basim, Washington, D. C., .assignon hy mesme assignments, to Bendix Radio Corpora'- tion,.New York, RLY., a corporation of Delawa. e

`Application November 20, 1935, Serial No. 50,774'

c claims. (ci. 250g-s6) This invention relates to electricalv discharge device oscillation generators generally. More particularly this invention relates to electrical discharge device oscillation generators'of a high frequency stabilityz An object of this invention is to provide an oscillation generator employing an electric discharge device adapted to generate electrical oscillations of extremely constant frequency with- 10 out the use of any auxiliary means. t y

Another object of this invention is to provide an oscillation generator employing an electric discharge device adapted to generate electrical l5 oscillations of extremely constant frequency over wide temperature variations ofthe discharge device without mechanical compensation or without the use of auxiliary frequency control means.

Still another object of this invention is to provide 'an electric discharge device oscillation generator of extremely high frequency stability by employing temperature-responsive-voltagevarying means to control the`potential applied to electrodes of the discharge device in accordance with temperature variations.

Another object of this invention isto provide an electric discharge device oscillation generator of extremely high frequency stability in which electric potentials applied to selected electrodes 'of the discharge device s :e varied in response to temperature variations.

A further object of this invention is to provide an electric discharge device oscillation generator of extremely high frequency stability employing circuit components having substantially no tem- J perature expansion throughout Wide temperature ranges and employing means for counteracting eifects ofoperating temperature variations in the electric discharge device.

Another object of this invention is to provide an electric discharge device oscillation generator of relatively high frequency stability employing a multiple grid electrode or a singlegrid electrode electric discharge device employing an oscillatory circuit having a temperature coefficient of substantially zero and employing temperature responsive voltage regulating means to adjust po tentia'ls applied to the electric discharge device to compensate for the effects of temperature on the frequency of the oscillations generated in the electric discharge device. Other and further objects of this invention will be apparent from the following specification and theclaims.

In accordancewith this invention I provide an frequency control oscillation generator adapted to generate electrical oscillations of substantially constant frequency. The arrangement of my invention employs an electric discharge device having a cathode, an anode and'one or more gridlike electrodes. 5 An oscillatory circuit, including inductance and capacity elements, is connected to selected elec trodes ofthe electric discharge device. Suitable sources of current supply fo-r energizing the cathode' and anode circuits are also employed. vl0

A resistor having a positive resistance-temperature coeiiicient is connected in series with the cathode and a resistor having a positive resistanceftemperature coeicient is connected in series with the anodecurrent supply. The values 1 5 of these resistors are adjusted to give the proper variation in potentalsapplied to the discharge device electrodes throughout Wide temperature ranges.

Each, of these variations inthe potentials 2o caused by these resistors, considered separately or A individually, would effect a certain frequency change in theoscillations generated by the oscillation generator. However, the eiiects of the variations 'are.such, in the circuit arrangement 25 of my invention, as to counteract and maintain the frequency generated substantially constant even though the electric discharge device frequency characteristics change slightly because of temperature changes.

Further details of this invention will be appar.- ent from the following specification and the drawing in which, briefly, Fig. 1 illustrates an embodiment of my invention employing the series anode excitation three electrode electric discharge 35 device; Fig. 2 shows an embodiment employing the parallel anode excitation three electrode electric discharge device; and Fig. illustrates a multiple grid electric discharge device circuit ar. rangement embodying my invention.

Referring to Figure l in detail, reference numeral i designates a three-element electric discharge device having a cathode 2, a grid electrode 3, and an anode d. This electric discharge device may be of any conventional design adapt- 45 ed to generate or control the production of electric oscillations. The grid electrode 3 is connectedrto the oscillatory circuit 5 which includes the inductance 6 .and the variable condenser l. The inductance 6 is preferably wound with rela- 50 tively ne Wire on a form of ceramic material,

such as, isolantite or other insulating materials such as, fused quartz, boro-silicate glass and vitreous compositions having a low coemcient of thermal expansion. The purpose of constructing 55 this' inductance. in this manner is to produce a y unit, the physical dimensions of which do not vary appreciably with normal temperature changes.` The wire or conductor of the inductance may be wound on a suitable form of vitreous or glass material and fused-into the vitreous or glass form', thus producing an' inductance unit with substantially permanent characteristics. The variable condenser 'I also is constructed to havea lowv 4temperature coelcient whereby the electrical capacity thereof does not vary appreciably with norranges of temperatures.v The inductance 8 which is coupled to the inductance 6 is also wound'withmal changes in temperature. The conducting plates of the condenser 'I are made of invar 4or similar allyjiavlng a low coefficient of thermal expansion'. The .oscillatory circuit, comprising the inductance 6 and the condenser 1, when adjusted to a. predetermined frequency, will maintain that adjustment accurately throughout wide relatively ne. wire on a form of material, such as lsolantite.

A high frequency by-pass lcondenser 9 is cont nected between the cathode 2 and the oscillatory circuit 5. Another condenser I is connected between the inductance 8 and the oscillatory circuit 5.- The pointat which the condensers 9 and Ill are connected to the oscillatory circuit is also grounded to the metal chassis or frame which is employed to support the component parts of the oscillation. generator. A resistor II having a positive resistance-temperature coemcient is connected across the condenser 9 between the cathode-2 and theoscillatory circuit E. This resistor II is preferably wire wound on a suitable insulation form made of ceramic material or the like. Another resistance unit I2 is'connected to a point between the inductance 8 and the condenser I8 and to the positive terminal of the source of anode currentsupply I 3. This resistor is also made to' have a positive resistance-temperature coefiicient.

The resistors Il and I2 may be wound with wire made-of nichrome, manganin, or other alloys suitable for electrical resistance units, having different temperature coelcients.

The purpose of the resistors I I and I2 is to provide automatic compensation for frequency drift or Achangewhich occurs in the discharge device I due to changes in ambient temperature to which the discharge device is subjected during operation; It has been found that when the normal frequency drift or change in an oscillation gencrater, such as, shown in Figure l, is in the negative direction, that is, when the `frequency decreases'as the temperature is increased, that compensation for this frequency change can be obltained either by increasing the voltage on the cathode or decreasing the voltage on the anode, or both. An vincrease in the ambient temperature willause the resistors Il and I2 to increasein value, thus increasing the voltage on the cathode and decreasing the voltage on the anode, causing the frequency of the oscillations generated to increase. By properly proportioning the characanimee oscillatory circuit 5, must be designed with extreme care, as outlined above in the description of this oscillatory circuit, for example.

'I'he complete oscillator is enclosed in a suitable `cabinet made of shielding materials such as aluminum and the like. Where desired, the cabinet may be made with heat insulating walls.

An oscillation generator of the parallel anode excitation type is illustrated in Figure 2. This oscillation generator employs an electric discharge device I, an oscillatory .circuit 5. and a pair lof resistors I I and. I2 similar to the discharge device I, oscillatory circuit 5 and resistors Il and I2 shown in Figure 1. The distinction between this oscillation generator and that shown in Figure 1 is that the source of current supply I3 is connected in parallel with the anode-cathode circuit of the discharge device I through a high frequency choke coil I4 instead of in series with the anode-cathode circuit as shown in Figure 1.

An embodiment of this invention 'employing a multiple grid discharge device la is shown in Figure 3. This discharge device I a. is provided with a cathode 2, a plate Q, and grid- like electrodes 3, 3a, and 3b. The electrode 3 is connected to the oscillatory circuit 5 including the inductance 8 and the capacity 1.. The electrode 3a is connected to the inductance 8 and functions as the anode oi' theoscillation generator. The electrode 3b is connected to ground, that is, to the metal chassis andl cathode circuit. The plate l is' connected to the resistor I5 and to the coupling condenser I8. The other terminal of the resistor I5 is connected to the positive terminal of the source of current supply 'I3 and to theresistor I2. Y The resistors II and I2y are made in substantially the same way as the resistors II and I2 of Figs. 1 and 2. However, the resistor I5 is made to have a negative resistance-temperature coemcient and is made of material such as carbon and the like, having negative temperature coeillcients. l

vThe purpose of the resistor I5 is to cause an increase in the voltage supplied to the plate or coupling electrode i as the ambient temperature increases. This is accomplished by making the resistor I5 of material having a negativetemperature coemcient such that the resistance value of this resistor decreases as the tentiperaturev lncreases. 'I'he eil'ect of increasing the voltage of the coupling electrode 4 is. to increase the frequency of the oscillations generated by the discharge device Ia.

The coupling condenser I6 is provided for the purpose of coupling the oscillation generator to a Work circuit, or a circuit in which the oscillations produced are to be utilized. Oscillations of considerable power and 4amplitude may be derived from the circuit of the generator shown in Figure 3 without endangering the frequency stability thereof. This does not appear to be the case with oscillation generators shown in Figures 1 and 2, inasmuch as the power output of these types is rather limited if the high frequency sta- .bility is to be maintained. However, the generators shown in Figures 1 and 2 may be employed to advantage in-cases where low power output is desired.

The source of current supply I3, illustrated in each case as a battery, may be a suitable generator or a rectified alternating current source the voltage of which is maintained substantially constant.

Suitable heater electrodes are also provided to each of the electric discharge device cathodes as is conventional in indirectly heated type cathodes animee 1 of electric discharge devices. IThe heater may be energized from a battery or any other convenient source oi' current supply.

Various modiications in the details of my invention may be made therein without departing from the spirit and scope thereof and therefore I do not desire to limit this invention to the exact details described in the foregoing specication except insofar as they are deined by the claims.

What I claim and desire to secure by Letters Patent of the United States is as follows:

1. Anoscillation generator adapted to generate electrical oscillations oi a high degree of frequency stability, comprising an electric discharge 1 device having a cathode, a control electrode and an anode, an oscillatory circuit connected to said control electrode and said cathode, an inductance for coupling said anode to said oscillatory circuit, a source of current supply for energizing said anode, connections for connecting the negative terminal of said source of current to said oscillatory `circuit, a resistor having a positive temperature coefilcient connected in series with said source of current supply and said coupling inductance for decreasing the anode energizing potential with increase in ambient temperature and a second resistor having a positive temperature coemcient connected between said cathode of said discharge device and said oscillatory circuit, for increasing the potential of said cathode with increase in temperature said resistor being adapted to cooperate together to compensate for the c ects of temperature changes on the frequency of the oscillations generated by said electric discharge device.

2. An oscillation generator adapted to generate electrical oscillations of a high degree of frequency stability, comprising an electric discharge device having a cathode, a control electrode and an anode, an oscillatory circuit having a substantially zero temperature-frequency coetoient, con" nections between said oscillatory circuit and said electric discharge device, a source of current supply connected to the anode of said electric discharge device, a pair of impedance elements having positive temperature coefcients, connections for connecting one of said impedance elements between said source of current supply, and said anode for decreasing the energizing potential applied to said anode as the ambient temperature increases and connections for connecting the other of said impedance elements between said 'cathode and said source oi current supply for increasing the eectivepotential of said cathode as the said ambient temperature increases the voltage variations in said impedance elements being adapted to compensate the e'ects oi ambient temperature variations on the frequency of the oscillations generated by said discharge device.

3. An oscillation'generator adapted to generate electrical oscillations of a high degree of frequency stability, comprising an electric discharge device, means including said electric discharge device forgenerating electrical oscillations of a predetermined frequency and means connected to said electricdischarge device for varying the magnitude of selected potentials applied thereto in accordance with variations in ambient temperature for compensating for the edects of variations in said ambient temperature on the frequency of the oscillations generated.

4. An oscillation generator adapted to generate electrical oscillations of a high degree of ire-l quency stability, comprising an electric discharge device having a cathode, a control electrode, an anode, and a coupling electrode, an oscillator; circuit having a substantially zero temperaturefrequency coecl'ent, connections between said oscillatory circuit and said ,electric discharge device, a source of current supply connected to the anode of said electric discharge devicefa.

pair of impedance elements having positive temperature coenicients. connections between said impedance elements and rsaid source of current supply, and an impedance element having a negative temperature coecient connected between said source of current supply and said coupling electrode, the voltage variations in said impedance elements being adapted to compensate the eilects of ambient temperature variations on the frequency of the-oscillations generated by said discharge device.

5. An oscillation generator adapted to generate electrical oscillations of a high degree of frequency stability, comprising an electric discharge device having a cathode, a control electrode, an anode, and a couplingelectrode, an oscillatory circuit connected to said control electrode and said cathode,'means for Vcoupling said anode to said oscillatory circuit, a source of current for energizing said anode, a resistor having a positive temperature co'emcient connected in series with said source oi current supply and said means, a second resistor having a positive temperature coemcient connected in series with the cathode of said discharge device and said oscillatory circuit, and a resistor having a negative temperature coecient connected between said coupling electrode and said source of current, said resistors being adapted to compensate for the effects of temperature changes on the irequency of the oscillations generated by said electric discharge device.

6. .en oscillation generator adapted to generate electrical oscillations oi a high degree of frequency stability', comprising an electric discharge device, means including said electric discharge device :for generating electrical oscillations of a predetermined frequency and resistance means responsive to temperature changes, connections between said resistance means and said electric discharge device for varying the magnitude of selected potentials applied thereto in accordance with variations in ambient temperature for compensating for the eectof variations in said ambient temperature on the frequency of the oscillations generated.

DONALD BASM.

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