US2305911A - High efficiency loss modulator - Google Patents

High efficiency loss modulator Download PDF

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Publication number
US2305911A
US2305911A US371094A US37109440A US2305911A US 2305911 A US2305911 A US 2305911A US 371094 A US371094 A US 371094A US 37109440 A US37109440 A US 37109440A US 2305911 A US2305911 A US 2305911A
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US
United States
Prior art keywords
modulation
tube
circuit
anode
diode
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
US371094A
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English (en)
Inventor
Frederick E Terman
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.)
International Standard Electric Corp
Original Assignee
International Standard Electric Corp
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Priority to NL65727D priority Critical patent/NL65727C/xx
Application filed by International Standard Electric Corp filed Critical International Standard Electric Corp
Priority to US371094A priority patent/US2305911A/en
Application granted granted Critical
Publication of US2305911A publication Critical patent/US2305911A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03C—MODULATION
    • H03C1/00—Amplitude modulation
    • H03C1/08—Amplitude modulation by means of variable impedance element
    • H03C1/14—Amplitude modulation by means of variable impedance element the element being a diode

Definitions

  • This invention relates to modulators, and more particularly to absorption or lossmodulators' of relatively high efficiency; a p
  • the efficiency of a modulator of the type disclosed in the above-named patent is further improved by using a rectifier in the system as a losser tube, and connecting the rectifier to oppose the direct current anode supply potential of the highfrequency generator or amplifier tube.
  • Fig. 1 is a circuit diagram showing my invention applied to the modulation of energy supplied from an amplifier
  • Fig. 2 shows my invention applied to modulation of energy in an oscillation generator.
  • a high impedance choke coil L2 is provided in the anode lead from battery 6.
  • a radio frequency choke 5 is provided in series with Lz.
  • the modulating voltage is applied from coil 6 in series with the diode, and the tank circuit LC is so adjusted that the peak radio frequency voltage applied to the diode under carrier conditions, that is with no modulation signal being applied, is just greater than the direct current bias of the cathode. In the present case where the full plate voltage is applied to the cathode this means that the peak voltage is slightly greater than the D. C. plate voltage for tube I.
  • the audio-frequency modulating voltage must be sufficient to vary the potential between the cathode and ground of diode 3 from zero to twice the plate-supply voltage.
  • the audio-frequency current that flows through the diode has a peak value very nearly equal to the D. C. current through the losser under carrier conditions.
  • the modulating power is approximately P/2 where P is the carrier power.
  • the modulating power is accordingly m P/2. This is slightly less than the amount of audio-frequency energy required for plate modulation.
  • the output power to be the modulated wave rises Slightly with modulation, being substantially 69% for complete modulation of the 500 watt carrier in the numerical case given above.
  • the limit of depth of modulation is set by the fact that although the load impedance ofiered to the modulating voltage by the diode circuit is substantially constant for most of the operating range, this impedance drops abruptly to a very low value when the envelope of the modulated wave reaches zero. This limitation is not particularly severe, however, and actual experimental results have indicated less than 10% distortion with 95% modulation without the use of any negative feedback to improve the operation.
  • Fig. 2 a circuit wherein an oscillation generator is used as the source of the radio frequency waves.
  • the tube l is supplied with a tank circuit LC connected between the anode and grid of the tube through a coupling condenser 2.
  • supply for tube l is provided over a high impedance choke L2 and RF choke 5.
  • Diode 3 is connected with its anode to a point on the tank circuit LC, and its cathode is connected over the coupling coil 7 to the positive anode voltage for tube
  • the output for the modulated signal is coupled by means of a coil 8 to the coil of the tank circuit L.
  • the direct current plate which has been here described is relatively simple and is capable of virtual complete modulation. For a given carrier output the circuit requires slightly less modulating power than a corresponding plate modulated system. The efiiciency that can be realized is in the order of unmodulated and when fully modulated.
  • a modulation system comprising an electron discharge device having an output circuit to which oscillating power is supplied by said device, anode potential supply means for said device, a circuit including a source of modulating voltage and a rectifier connected in series, and means for connecting said series circuit between a point in said output circuit and a positive potential point of said anode potential supply means.
  • a modulation system comprising an electron discharge device having an output circuit to which oscillating power is supplied by said device. a source of anode potential for said device, means intermediate said source of anode potential and said electron discharge device for maintaining the direct anode current of said electron device constant, a circuit including a source of modulating voltage and a rectifier connection in series, and means for connecting said series circuit between a point in said output circuit and a positive potential point of said anode potential source.

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  • Amplifiers (AREA)
US371094A 1940-12-21 1940-12-21 High efficiency loss modulator Expired - Lifetime US2305911A (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
NL65727D NL65727C (enrdf_load_stackoverflow) 1940-12-21
US371094A US2305911A (en) 1940-12-21 1940-12-21 High efficiency loss modulator

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US371094A US2305911A (en) 1940-12-21 1940-12-21 High efficiency loss modulator

Publications (1)

Publication Number Publication Date
US2305911A true US2305911A (en) 1942-12-22

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US371094A Expired - Lifetime US2305911A (en) 1940-12-21 1940-12-21 High efficiency loss modulator

Country Status (2)

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US (1) US2305911A (enrdf_load_stackoverflow)
NL (1) NL65727C (enrdf_load_stackoverflow)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2429683A (en) * 1940-06-12 1947-10-28 Hartford Nat Bank & Trust Co Modulation

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2429683A (en) * 1940-06-12 1947-10-28 Hartford Nat Bank & Trust Co Modulation

Also Published As

Publication number Publication date
NL65727C (enrdf_load_stackoverflow)

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