US2095371A - Modulation - Google Patents

Modulation Download PDF

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Publication number
US2095371A
US2095371A US749727A US74972734A US2095371A US 2095371 A US2095371 A US 2095371A US 749727 A US749727 A US 749727A US 74972734 A US74972734 A US 74972734A US 2095371 A US2095371 A US 2095371A
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United States
Prior art keywords
grid
voltage
tube
screen
anode
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Expired - Lifetime
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US749727A
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English (en)
Inventor
Rohnfeld Johannes
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Telefunken AG
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Telefunken AG
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Publication date
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Publication of US2095371A publication Critical patent/US2095371A/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
    • H03C1/24—Amplitude modulation by means of discharge device having at least three electrodes carrier applied to control grid modulating signal applied to different grid

Definitions

  • Figs. 2, 4 ⁇ ⁇ 6, 8 illustrate the modulation characteristics, i. e., the relatio'n between the plate alternating V voltage e. and the plate direct current voltage 40 Ea, inthe presence of constant radio frequency control grid alternating voltage, which areinsured in the presenceof conditions shown in Figs ⁇ '1', '3;, 5 7, between the potentials Ea arising at the plate and Beat the screen grid.
  • Figures 9 to 13 inclusive illustrate various circult arrangements each including meansfor applying modulation potentials simultaneously to the anode and another electrode in a thermionic tube.
  • l I V In the case of Fig. 1, conditions are so arranged that there prevails a linear relationship between applied platevoltage E5 and applied screen grid voltage'Es; In the examplehere chosen, the ratiofbetween the two is 25%, in other words, the screen-grid voltage amounts to only one-fourth 'of the-plate voltage. V The assumption is more,-
  • ea is radio frequency anode voltage plotted as ordinates 7 against anode voltage plotted as abscissa, it being understood that the relation between anode volt-' age Ea and screen grid voltage Es is maintained as shown by the graph in Fig. 1 while plotting the graph of Fig. 2.
  • the characteristic is 7 straight only within the median ranges;
  • Figs. 9-13 To illustrate circuit schemes wherein modu- Iatloncharacteristics of the kind shown above may .be obtained, a number of exemplified embodiments are shown in Figs. 9-13. Referring to the same, It is the tube to be modulated, K is the direct current blocking condenser, D a radio frequency choke-coil, S the oscillation circuit,
  • the circuit organization of Fig. 9 serves for realizing the characteristics shown, in Figs. 1 and 2.
  • the tube R has its control grid and cathode connected to a carrier wave source not shown.
  • the anode of R. is coupled to the cathode of R by a blocking condenser K and a tuned circuit S.
  • the latter is coupled to a load circuit which, for purposes of illustration is shown as an aerial system.
  • Modulating potentials are applied from a source not shown to the primary winding of transformer M, the secondary winding of which is connected to a potentiometer P.
  • One terminal of P is connected to the anode of R by way of a radio frequency choke D.
  • a point on P is connected to the screen electrode of R.
  • the other end of P is connected by the source of direct current potential to the cathode of R.
  • the relation of four to one may be maintained between the anode voltage and screen grid voltage, as shown in Fig. 1, by adjusting the point on P, to get'the modulation characteristic as shown in Fig. 2.
  • Operating states as shown in Figs. 3 and 5, and Figs. 4 and 6, respectively, are obtainable by circuit arrangements of the kind illustrated in Figs. 10-12.
  • a special counterdirect current voltage source G is provided which serves the purpose of preventing the screen grid from obtaining a voltage equal to the plate voltage.
  • the alternating voltages to be fed to the screen grid are obtained by tapping the modulation transformer M.
  • a non-linear device N which here, for instance, consists of a supplementary electron tube.
  • the device N comprises a thermionic tube having its control grid connected to a point on the secondary winding of M and its anode connected to the screen grid of R.
  • the cathode of the tube in N is connected to a point on a source of potential in series with a resistance connected between the screen grid of R and the lower end of the secondary winding of M.
  • the bi-linear relation between the anode voltage Ea and the screen grid voltage Es shown in Fig. '7 may be obtained.
  • the first part of the graph is linear and rises steeply, as shown in Fig. 3, while the upper end of the graph is linear but rises less steeply, as shown in Fig. 4.
  • the bilateral relation between the screen grid voltage and anode voltage combine to give a modulation characteristic linear throughout its length, as shown in Fig. 8.
  • a device for modulating carrier wave oscillations at signal frequency comprising, a thermionic tube having an anode, a cathode, and a control grid electrode, and a screen grid electrode, a carrier wave energizing circuit connected to the control grid and cathode of said tube, a source of modulating potentials, a reactance connected between a point on said source of modulating potentials and the anode of said tube, a connection between said source of modulating potentials and the cathode of said tube, and an impedance of non-linear character connected between the screen grid of said tube and said source of modulating potentials.
  • a thermionic tube having an anode, a cathode and a control grid and a screen grid electrode, a carrier wave energizing circuit connected to the control grid and cathode of said tube, an impedance on which signaling potentials may be impressed, a circuit connecting said impedance between the anode and cathode of said tube, and a circuit including an impedance of non-linear character connecting a point on said first named impedance to the screen grid of said tube.
  • a thermionic tube having an anode, a cathode, a control grid, and a screen grid, a circuit connected with the control grid and cathode of said tube for applying carrier wave oscillations to be modulated to the control grid and cathode of said tube, an impedance connected with a source of modulating potentials, a source of direct current potential connecting one terminal of said impedance to the cathode of said tube, a circuit connecting the other terminal of said impedance to the anode of said tube, and a circuit including a non-linear impedance connecting the screen grid of said tube to a point on said first impedance.
  • a system as recited in claim 3 in which a source of potential is interposed in said circuit connecting said screen grid to said point on said first impedance.
  • a thermionic tube having an anode, a cathode and a control grid and a screen grid, a circuit for applying carrier wave oscillations to be modulated to the control grid of said tube, a modulation frequency transformer having a primary winding which may be connected to a source of modulating potentials, said transformer having a secondary winding, a source of direct current potentials connecting the secondary winding of said transformer between the anode and cathode of said tube, an additional thermionic tube having an anode, a
  • cathode and a control grid a circuit connecting the anode-to-cathode impedance of said additional tube between the screen grid of said first named tube and a point on said secondary winding, and a connection between the control grid of said additional tube and a point on said secondary winding.

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  • Amplifiers (AREA)
  • Amplitude Modulation (AREA)
US749727A 1933-10-25 1934-10-24 Modulation Expired - Lifetime US2095371A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE436922X 1933-10-25

Publications (1)

Publication Number Publication Date
US2095371A true US2095371A (en) 1937-10-12

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US749727A Expired - Lifetime US2095371A (en) 1933-10-25 1934-10-24 Modulation

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US (1) US2095371A (en(2012))
DE (1) DE623602C (en(2012))
FR (1) FR779837A (en(2012))
GB (1) GB436922A (en(2012))

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2862187A (en) * 1956-11-06 1958-11-25 Gen Electric Signal modulating system
US2883626A (en) * 1955-04-22 1959-04-21 Rca Corp Modulation or gain control system and method

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2883626A (en) * 1955-04-22 1959-04-21 Rca Corp Modulation or gain control system and method
US2862187A (en) * 1956-11-06 1958-11-25 Gen Electric Signal modulating system

Also Published As

Publication number Publication date
FR779837A (fr) 1935-04-13
GB436922A (en) 1935-10-21
DE623602C (en(2012))

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