US2491754A - Radio transmitting circuits - Google Patents

Radio transmitting circuits Download PDF

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Publication number
US2491754A
US2491754A US783995A US78399547A US2491754A US 2491754 A US2491754 A US 2491754A US 783995 A US783995 A US 783995A US 78399547 A US78399547 A US 78399547A US 2491754 A US2491754 A US 2491754A
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United States
Prior art keywords
frequency
anode
valve
pulses
circuit
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Expired - Lifetime
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US783995A
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English (en)
Inventor
Moss Hilary
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
AC Cossor Ltd
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AC Cossor Ltd
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Filing date
Publication date
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Publication of US2491754A publication Critical patent/US2491754A/en
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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03C—MODULATION
    • H03C1/00—Amplitude modulation
    • H03C1/16—Amplitude modulation by means of discharge device having at least three electrodes
    • H03C1/18—Amplitude modulation by means of discharge device having at least three electrodes carrier applied to control grid
    • H03C1/20—Amplitude modulation by means of discharge device having at least three electrodes carrier applied to control grid modulating signal applied to anode

Definitions

  • This invention relates to radio frequency modulators and has among its objects that of obtaining amplitude-modulated radio frequency waves with very low distortion at modulation depths up to 100%.
  • One way in which this object is attained is by the use of heavy negative feedback in the manner to be described.
  • th circuit shown in Figure 1 there are connected between the positive line and earth a potentiometer R1, R2 and a valve circuit of the cathode lead resistor type consisting of a valve V1 with a resistor R3 between its cathode and earth.
  • the rid of V1 is directly connected to the point P in the potentiometer R1, R2.
  • the valve V1 is a short grid-base triode, and the line voltage +V is very large in comparison with the grid bias of V1: then the cathode of V1 and the point P are at substantially the same potential.
  • the current 1' through the valve V1 iS is thus proportional to the line voltage V.
  • valve V1 will be pulse modulated in phase with the grid pulses and by the reasoning discussed in connection with Figure 1, the peak current will beproportional to the line or plate 2 V voltage. This current will fall to zero on receipt of each negative-going pulse at the grid.
  • FIG. 3 shows a practical circuit incorporating these principles.
  • the anode load of the valve Vi incorporates the tuned resonant circuit L1G; which resonates at the carrier frequency, and also the low frequency transformer K which injects the audio-modulation by variation of the instantaneous anode potential of the valve V1.
  • the condenser 02 decouples the radio frequency output.
  • the cathode bias resistor R3 is shunted by C1 and the value of C1 is so chosen as to prevent negative feedback at the radio frequency, but not at the modulating audio-frequency.
  • the radio frequency input to V1 is injected across R4 by means of a tuned high frequency transformer.
  • the rectifier T results in unidirectional current pulses through R4 and is so connected that the grid is driven negative with respect to P.
  • V1 is being pulsed negatively by a substantially square wave and the anode current will consist of similar square waves, the peak amplitude of which corresponds to the condition where the grid potential is the potential at P, i. e. rectifier T non-conducting.
  • the tuned circuit L1C3 converts the square pulses into sinusoidal waves.
  • R3 50,000 ohms
  • R4 25,000 ohms
  • C1 0.01 pf.
  • valve V1 42SPT The valve V1 42SPT.
  • the recurrence frequency of the pulses applied to the grid of valve V1 need not necessarily be equal to the resonance frequency of the tuned circuit L103 arranged in the anode circuit of the valve for converting the pulses of anode current into sinusoidal waves, but may be some multiple or sub-multiple thereof provided the said tuned circuit will resonate at the desired carrier frequency in response to pulses of that recurrence frequency.
  • a radio-frequency modulator for modulating an oscillation of a desired radio frequency comprising a thermionic valve, circuit means for maintaining the anode current of the valve substantially proportional to its anode potential at the said frequency, a source of voltage pulses of a predetermined recurrence frequency, means for applying said pulses to the control grid of the valve, a source of modulation voltage, means for applying said modulation voltage to the anode of the valve, and a circuit which resonates at the desired frequency in response to an anode current pulsating at saidrecurrence frequency so as 'to' produce an amplitude-modulated substantially-sinusoidal oscillation of desired carrier frequency.
  • a radio-frequency modulator comprising a thermionic valve, a resistor having one terminal connected to the cathode of said valve, a potential divider connected between the anode of said valve and the other terminal of said resistor, a source of radio-frequency pulses applied between a point in the potential divider and the control grid of the valve, a source of modulating oscillations applied between a source of anode voltage and said anode, and a circuit which resonates at a desired carrier-frequency in response to pulses of the said radio-frequency for deriving from the amplitude-modulated pulsating anode current in amplitude-modulated substantially sinusoidal oscillation.
  • a radio-frequency modulator for modulatin an oscillation of a desired radio frequency comprising an electron discharge valve having an anode, a cathode and at least one control electrode, circuit means for maintaining the current between said anode and cathode substantially proportional to the potential of said anode at said radio frequency, means for applying voltage pulses to said control electrode and means for applying modulating voltage to said anode.
  • a radio-frequency modulator for modulating an oscillation of a desired radio frequency comprising an electron discharge valve having an anode, a cathode and at least one control electrode, a resistor connected between said cathode and a point of fixed potential, 9. potential divider connected between said anode and said point of fixed potential, an impedance connected between a tapping intermediate the ends of said potential divider and said control electrode, means for applying voltage pulses across said impedance and means for applying modulating voltage to said anode.
  • a modulator according to claim 5, wherein said means for applying voltage pulses across said impedance comprise a source of substantially sinusoidal oscillations and a rectifier for producing said voltage pulses from said sinusoidal oscillations.
  • a radio-frequency modulator for modulating an oscillation of a desired radio frequency comprisin an electron discharge valve having an anode, a cathode and at least one control electrode, a resistor in parallel with a capacitor connected between said cathode and a point of fixed potential, a potential divider connected between said anode and said point of fixed potential, means for applying Voltage pulses between a point intermediate the ends of said potential divider and said control electrode and means for applying modulating voltage between said anode and said point of fixed potential.
  • a modulator according to claim 8 wherein there is connected to said anode a circuit tunable to said resonance frequency.
  • a modulator according to claim 10, wherein the recurrence frequency of said voltage pulses is an integral multiple of said resonance frequency.
  • a modulator according to claim 8, wherein said means for applying voltage pulses comprise a transformer having a secondary winding tuned to the recurrence frequency of said voltage pulses.
  • said means for applying voltage pulses comprise a transformer having a secondary winding tuned to the recurrence frequency of said voltage pulses, a rectifier connected in said secondary winding, and a source of oscillations connected to the pri mary winding of said transformer.

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  • Amplitude Modulation (AREA)
  • Amplifiers (AREA)
US783995A 1946-11-08 1947-11-04 Radio transmitting circuits Expired - Lifetime US2491754A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB33314/46A GB619156A (en) 1946-11-08 1946-11-08 Improvements relating to radio frequency modulators

Publications (1)

Publication Number Publication Date
US2491754A true US2491754A (en) 1949-12-20

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
US783995A Expired - Lifetime US2491754A (en) 1946-11-08 1947-11-04 Radio transmitting circuits

Country Status (4)

Country Link
US (1) US2491754A (de)
FR (1) FR955149A (de)
GB (1) GB619156A (de)
NL (1) NL71878C (de)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3608358A1 (de) * 1986-03-13 1987-09-17 Licentia Gmbh Verfahren und anordnung zur anodenmodulation einer senderendstufenroehre

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2266401A (en) * 1937-06-18 1941-12-16 Int Standard Electric Corp Signaling system

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2266401A (en) * 1937-06-18 1941-12-16 Int Standard Electric Corp Signaling system

Also Published As

Publication number Publication date
GB619156A (en) 1949-03-04
NL71878C (de)
FR955149A (de) 1950-01-10

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