US2349811A - Reactance tube modulation - Google Patents

Reactance tube modulation Download PDF

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Publication number
US2349811A
US2349811A US433745A US43374542A US2349811A US 2349811 A US2349811 A US 2349811A US 433745 A US433745 A US 433745A US 43374542 A US43374542 A US 43374542A US 2349811 A US2349811 A US 2349811A
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United States
Prior art keywords
tube
circuit
reactance
grid
control
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US433745A
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English (en)
Inventor
Murray G Crosby
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RCA Corp
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RCA Corp
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Filing date
Publication date
Priority to NL60549D priority Critical patent/NL60549C/xx
Priority claimed from US311074A external-priority patent/US2278429A/en
Priority to CH230608D priority patent/CH230608A/de
Application filed by RCA Corp filed Critical RCA Corp
Priority to US433745A priority patent/US2349811A/en
Application granted granted Critical
Publication of US2349811A publication Critical patent/US2349811A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03C—MODULATION
    • H03C3/00—Angle modulation
    • H03C3/10—Angle modulation by means of variable impedance
    • H03C3/12—Angle modulation by means of variable impedance by means of a variable reactive element
    • H03C3/14—Angle modulation by means of variable impedance by means of a variable reactive element simulated by circuit comprising active element with at least three electrodes, e.g. reactance-tube circuit
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03C—MODULATION
    • H03C3/00—Angle modulation
    • H03C3/02—Details
    • H03C3/09—Modifications of modulator for regulating the mean frequency

Definitions

  • a feature of my .application is a circuit arrangement wherein the modulating potentials are applied between a control electrode of one of the tubes and ground. This permits one side of the.
  • tube i is coupled to circuit also so that the. re-
  • Figure 3 is a modification of the arrangement of Figure 1; while Figures 3a and 3b are curves and graphs used to explain the operation of the reactance tube circuits.
  • tube I which is the reactance tube
  • circuit 5 connects the grid 8, cathode l0, and screen grid l2 of an electron-coupled oscillator tube in regenerative circuits for the production
  • the cathode 22 of the reactance active efllect produced intube 1 is of the oscillation generation circuit 5.
  • the control grid 24 of tube l * is coupled to the circuit 5 by p e shifting condenser C and the tuned reactance com- 20 prising inductance LI and condenser Ci.
  • 'Modulating or control potentials to control the reactive eifect are supplied at 28 to the control modulation circuit to be maintained at ground potential yet provides diflerentialmodulation of the reactance tubes.
  • Figure 1 illustrates an improved reactance tube circuit cooperating with a source of modulating potentials and an electron-coupled oscillation enerator to modulate the frequency of operation of the latter.
  • Figure 2 illustrates a novel circuit arrangement comprising two reactance tubes in a balanced circuit which hasa stabilizing eiIect on the oscillation generator circuits with a novel phase shifting rid 24'.
  • Tube I is the reactance tube which produces the reactive effect in its plate circuit.
  • This phase shifter is of the constant-current typein which the reactance of the capacitance C is made large compared to the impedance of the tuned circuit Li-Cl.
  • the capacitive reactance determines the phase of the current in the said circuit-so thatv the potential drop across the resistive tuned circuit Ll'-C
  • the degree of reactive effeet is controlled by the bias potentials on the grid 24. If the. grid is made mor positive the reactive effect increases. If the gridbecomes more negative the reactive efiect is decreased.
  • a resistive iiect is introduced in the variable reactance ef- Direct-current voltage is fed to the anode 2 of reactance tube I through radio-frequency choke RFC.
  • This voltag may I by means of a direct connection to the oscillator tuned circuit L2-C2 if the oscillator tuned circuit is of the type which has the plate voltage on it.
  • Capacitance ⁇ ! blocksthe reactance tube plate voltage from the tuned circuit L2-C2 of the oscillator tube 20.
  • the oscillator tube is of the electron-coupled type which supplies its output from tuned circuit L3-C3 electronically coupled to the generating circuits and electrodes.
  • Plate voltage is supplied by. lead 23 to the anode of tu 20.
  • Voltage' for the. screen grid l2 of tube 20 is s pplied from the plate source by means of potentiometer resistances 21 and 28.
  • the oscillations generated and controlled as to frequency in accordance with controlof the grid 24 of tube I is supplied through coupling condenser 150 any utilization means.
  • the circuit if controlled at 24-26 by modulating potentials produces frequency modulated waves. If controlled by AFC potentials oscillations of substantially constant frequency are produced.
  • the feed-back ca-' pacitance C may be eliminated and inductive coupling effected between inductances Li and L2. This would make the circuit a single-tube equivalso be supplied to oppose that fed to circuit 86 by C.
  • the opposition is caused by the back by C is at the opposite end of coil 58 which ,has the opposite polarity.
  • This opp'oslngfeedback would completely neutralize the reactive effect if C and C were made equal.
  • this equality is intentionally avoided by making C larger than C so that the predominate feedback is dueto C. This causes age appearing on grid 54 to be 180 out of phase with that fed to grid 24 since that voltage is predominantly fed from C through coil 58.
  • the circuit of Figure 2 shows a balanced type of 'reactanc'e tube circuit which I have found to, be very suitable for the production of oscillations of constant frequency due to advantages obtained by the balance.
  • I show a circuit employing this principle.
  • the circuitof said application "ing in the plate of tube 52 is inductive and has an effect on tuning which is opposite to that of I employ inductive coupling between the circuit circuits of the reactance tube i in the same manner as in Figure 1.
  • aura-2 second tube 52 is provided which gets on its grid 54 a feed-back voltage 180 out of phase with the voltage on the grid 24 of tube I.
  • the grid 24 derives a voltage through C of-a particular phasewhile the grid 54- of tube I52 gets by way of the tuned circuit comprising inductance 56 and condenser 58a voltage substantially 180 out of phase relative to the said voltage on grid 24. That is, if we assume zero phase of the voltages on anode 2 the voltage impressed by Con grid 24 is shifted 90' while the voltage im-; pressed.
  • rent supply potential to an electrode in the tubes causes variations in the current impulses.
  • This causes the actance which neutralizes the inductive rea'ctan'ce of the tube 52 aslong as the amplifications oi the two tubesare balanced.
  • Diil'crential modulation'of tube' lectrode voltages such as the. screens, suppressor grids, control grids, etc... however, causes an increase in the current impulses to. anode 2 atthe same time i that it causes a decrease inthe current impulse to the anode as and vice versa;
  • the voltage fedthe resulting volt-' of 58 to grid ll produce an increase oi the shunt capacitance at the same time that they produce an increase in the shunt inductancemr vice versa.
  • any cophasal modulation of the element voltages produces an effect in one tube which is compensated for by the other tube so that such undesirable variations are eliminated.
  • Th inductance 56 and condenser 58 are tuned to substantially the mean frequency at which the oscillator 20 is to operate.
  • the reactive eflect appears inthe common plate circuit of the two 4 tubes which may, as shown, be coupled by condenser 3 to the oscillator tuned circuit L2-C2 forv frequency stabilization and/or irequency modulation.
  • the reactance effects obtained by my invention may be applied to the tuned circuit of an amplifier and maintained under complete control of the modulating potentials. As a consequence, this arrangement is well adapted to use for phase modulation.
  • Variable capacitance C is the feed-back coupling condenser which corresponds to condenser C in Figure 1.
  • This capacitance may be composed of the internal grid-to-plate capacitance of the tube" together with added external capaci-- tance, if necessary, or, as I have found, may consist of the unbalance between the grid-to-plate capacitances of the two tubes 2 and 52 and their wiring.
  • Complete control of this capacitance is obtained when C is larger than the condenser C which may be connected between the grid 54 and plate 52 of the second tube so that the two may be relatively adjusted for complete neutralization or any degree of oil-neutralization desired.
  • the capacitance C usually is composed of the tube capacity only and for that reason is shown by dotted lines.
  • FIG. 2 shows how the balanced circuit may be arranged so as to be controlled by a control potential supplied at 26 with one side at low or 0 ground potential while at the same time retaining the advantage of the balanced reactance tube arrangement and differential modulation.
  • grid control is used and the control potential circuits are connected as shown to the grid 54 01' tube 52.
  • the reactive eifect will be completely balanced out when the control potential is zero.
  • the grid 54 oitube52 is made more positive. This causes tube 52 to draw more cathode current, and, therefore, places both cathodes at a higher positive potential due to the potential drop in cathode resistance I0 shuntedby bypass condenser I2.
  • This higher positive cathode potential is equivalent to a higher negative potential on the grid 24 of tube i.
  • the required differential control of the gain of the tubes I and 52 by the control potentials is obtained.
  • the common cathode resistor I0 causes the grid potential of the-one tube to vary in the opposite direction to that of the other.
  • this common cathode resistor III is not absolutely necessary because the circuit is difl'erentially unbalanced -by varying an element voltage of one tube, say 52, without varying that of theother tube, say I.
  • the common cathode resistor III tends to increase the sensitivity to control potentials and increases the range of reactance variation obtainable.
  • the wave generator dicated by a block diagram at 20" may be as lustrated in Figure 1 or of any typ known in the art.
  • the reactive eflect provides by the balanced arrangement comprising. tubes I and 52 stabilizes the operation of the generator which may also be controlled by potentials at 26, A common direct-current source or sources which vary in potential in synchronism rangement.
  • 5 Figure 3 is a circuitoi the balanced type which uses phase shifters which are untuned.
  • the phase shifter for tube I consists of resistance RI and capacitance C2. RI is made large compared to the reactance of'C2 so that the vector relations mxoithe circuit are as shown in Figure 3a.
  • E is the applied voltage which is supplied fromthe common plate circuits of tubes I and 52 and I is the current flowing in the phase shifter circuit RI, C2.
  • RI is the voltage drop across resistor RI and Kai is the voltage drop across capacitance C2.
  • the angle vbetween the applied voltage E and the drop across the capacitance C2, which is fed to the grid of tube I, is seen to be substantially 90 and, more nearly approaches 90 as the ratio between RI and C2 is increased.
  • the phase shifter for tube 52 consists otcapacitanc C3 and resistor R2.
  • the reactance of C3 is made large compared to resistance R2 so that the current is substantially reactive.
  • the vector diagram for the phase shifter R2, C3 is shown in Figure 3b. It can be seen that this ,type of phase shifter-produces a circuit of Figure 3 by means of the push-pull .feed from transformer 90 to the.suppressor grids 9i and 92.
  • Capacitances BPC are radio-frequency by-pass condensers and 94 is a blocking condenser.
  • Resistor 96 furnishes a direct-current return for the grid 24 of tube I.
  • the reactive eflect supplied to generator 20' stabilizes operation of the same which then may be controlled by potentials from 26.
  • Direct-current voltages which vary similarly are used here as in the prior modifications.
  • capacitances C2 and C3 may be replaced by inductances or the same reactance and the same balance action will be obtained.
  • these balanced circuits there are two methods by which the reactive effect 0 one tube may bebalanced against that 01' th other so that element voltage supply variations will be neutralized.
  • One of these methods is to balance the amount,of voltage fed back to each tube. This might be done by varying the relative sizes of the two halves vo1 the inductance 5B in Figure 2, or by varying the values of RI, C2, and R2, C3, in Figure 3. In any of these cases the balance would be made by increasing the voltage fed back to the tube which did not produce a large enough reactive effect.
  • the second method of balance is by means of the screen-grid balancing potentiometer.
  • C3 it has been round convenient in practice to have both of these types of balance available and to do so C3 was made variable and a screen-grid balancing potentiometer 68 -is included also.
  • reactance means for impressing phase displaced currents from said circuit on two electrodes in each of said devices to produce in said devices reactive effects, a biasing impedance in a common connection between the cathodes of said devices and a point of substantially fixed.
  • a pair of electron discharge devices each having an anode, a cathode, and a control electrode, a circuit parallel tuned to the frequency of said alternating current connected between the control electrodes of said devices, a; connection of low impedance to current of the frequency of said alternating current between a point on said'last circuit and the cathodes oi said devices; connections coupling the internal impedances between the anode and cathode of each of said'devices in shunt to a part at least of said first circuit, a reactance coupling the anode of one of said devices to the control electrode of said one device, an impedance connected between the cathodes of said devices and the control electrode of said one of said devices, and a source of control potentials in series with said impedance between the control electrode of the other'of said devices only and the cathodes of cuit'parallel tuned to the frequency
  • a circuit wherein oscillation energy, the wave length or which is to be modulated flows a pair of electron discharge devices each having an anode, a
  • a-pair of electron discharge devices each having an' electron receivingelectrode, an electron emission electrode and a control electrode, a sourceot alternating, current, means tying the'receivi'ng electrodes together and connecting thesame-to said source to set up on said receiving electrodes al;
  • an electron discharge device having an electron receiving electrode, an electron emission electrode, and an electron fiow control electrode, means coupling the impedance between the electron receiving electrode and the electron emission electrode.
  • said device in shunt to the reactance in said circuit wherein alternating currentjfiows, said .coupling setting up on said receiving electrode altera condenserin parallel tuned to the frequency of said alternating current, a 'reactance c'ouplingtlie electron receiving electrodeof said device to the electron flow control electrode of said device, conductors coupling said parallel inductance and condenser between the electron flow control electrode and electron emission electrode of said depfiow' control electrode, an alternating voltage which is substantially. in phase quadrature with.
  • said coupling reactance andinductance in parallel being arranged to set up on-said electron tron receiving electrode a resistance in, shuntto said parallel inductance and'condenserand conassaeii nections for modulating the gain of said device in accordance with control potentials to thereby control the reactive eirect produced in said device and added to said first named circuit.
  • 'L'In a wave length modulation ystem, a circuit wherein oscillatory current the wave length of which is to be modulated flows, 9. pair of electron discharge devices each having an electron receiving electrode. an electron emission electrode, and an electron flow control electrode, connections coupling the internal impedance between the electron receiving electrode and electron emission electrode of each of said devices in shunt to a part at least of the reactance in said 'iirst mentioned circuit, on inductance and a condenser in parallel tuned to the frequency of said oscillatory current, a reactance coupllm the electron receiving electrode of one device to the elec- Ill tron flow control electrode of said one device. conductors coupling said parallel inductance and condenser between the electron flow control electrodes of said devices.
  • a coupling between said parallel inductance and condenser andthe electron emission electrodes of said devices said coupling reactance and parallel tuned circuit serving to set up on the electron flow control electrodes of said devices opposed voltages of the frequency of said oscillatory current which are substantially in phase quadrature relative to the oscillatory voltages on the electron receiving electrodes of said devices, a source of modulating potentials and connections between said source of modulatins potentials and one of said device only for modulating the gain thereof in accordance with signals.

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US433745A 1939-12-27 1942-03-07 Reactance tube modulation Expired - Lifetime US2349811A (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
NL60549D NL60549C (enrdf_load_html_response) 1939-12-27
CH230608D CH230608A (de) 1939-12-27 1941-07-16 Schaltung mit einer oder mehreren Reaktanzröhren.
US433745A US2349811A (en) 1939-12-27 1942-03-07 Reactance tube modulation

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US311074A US2278429A (en) 1939-12-27 1939-12-27 Reactance tube modulation
US433745A US2349811A (en) 1939-12-27 1942-03-07 Reactance tube modulation

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US2349811A true US2349811A (en) 1944-05-30

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CH (1) CH230608A (enrdf_load_html_response)
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Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2419869A (en) * 1944-04-08 1947-04-29 Gen Electric Oscillation generator
US2438768A (en) * 1944-04-28 1948-03-30 Philco Corp Apparatus for varying the frequency of resonant cavities
US2485919A (en) * 1945-11-06 1949-10-25 Us Sec War Electrical circuit
US2515030A (en) * 1945-10-31 1950-07-11 Rca Corp Wave generation and control
US2555959A (en) * 1946-10-18 1951-06-05 Bell Telephone Labor Inc Nonlinear reactance circuits utilizing high dielectric constant ceramics
US2672509A (en) * 1949-04-01 1954-03-16 Mccoy John Harvey Teletypewriter frequency shift transmission
US2710378A (en) * 1951-04-28 1955-06-07 Motorola Inc Frequency modulation system
US2724802A (en) * 1953-03-05 1955-11-22 Rca Corp Frequency modulated oscillator
US2794957A (en) * 1952-12-13 1957-06-04 Motorola Inc Frequency modulator
US2817017A (en) * 1955-08-12 1957-12-17 Orville C Hall Frequency shift keyed oscillators
US2884598A (en) * 1955-04-01 1959-04-28 Hallicrafters Co Reactance modulator circuit and method
US2962672A (en) * 1955-11-28 1960-11-29 Blasio Conrad G De Dual-tube modulator and associated frequency-modulated crystal oscillator circuit therefor

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2419869A (en) * 1944-04-08 1947-04-29 Gen Electric Oscillation generator
US2438768A (en) * 1944-04-28 1948-03-30 Philco Corp Apparatus for varying the frequency of resonant cavities
US2515030A (en) * 1945-10-31 1950-07-11 Rca Corp Wave generation and control
US2485919A (en) * 1945-11-06 1949-10-25 Us Sec War Electrical circuit
US2555959A (en) * 1946-10-18 1951-06-05 Bell Telephone Labor Inc Nonlinear reactance circuits utilizing high dielectric constant ceramics
US2672509A (en) * 1949-04-01 1954-03-16 Mccoy John Harvey Teletypewriter frequency shift transmission
US2710378A (en) * 1951-04-28 1955-06-07 Motorola Inc Frequency modulation system
US2794957A (en) * 1952-12-13 1957-06-04 Motorola Inc Frequency modulator
US2724802A (en) * 1953-03-05 1955-11-22 Rca Corp Frequency modulated oscillator
US2884598A (en) * 1955-04-01 1959-04-28 Hallicrafters Co Reactance modulator circuit and method
US2817017A (en) * 1955-08-12 1957-12-17 Orville C Hall Frequency shift keyed oscillators
US2962672A (en) * 1955-11-28 1960-11-29 Blasio Conrad G De Dual-tube modulator and associated frequency-modulated crystal oscillator circuit therefor

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NL60549C (enrdf_load_html_response)
CH230608A (de) 1944-01-15

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