US2243193A - Modulation system - Google Patents

Modulation system Download PDF

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Publication number
US2243193A
US2243193A US272076A US27207639A US2243193A US 2243193 A US2243193 A US 2243193A US 272076 A US272076 A US 272076A US 27207639 A US27207639 A US 27207639A US 2243193 A US2243193 A US 2243193A
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Prior art keywords
tubes
high frequency
choke
source
point
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US272076A
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English (en)
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Clough Newsome Henry
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RCA Corp
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RCA Corp
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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 modulator circuit arrangements and has for its object to provide improved modulator circuit arrangements of high eficiency, comparative simplicity and cheapness, and comparative immunity from those known leakage resonance and similar disadvantageous efiects which occur in known high efficiency.
  • Fig. 1 illustrates somewhat diagrammatically my modulation system wherein two class C stages are connected in series by a choke coil and the stages are per se shunted by modulator tubes with each stage and the choke coil shunted by other modulator tubes, the modulator tubes operating class B and being modulated differentially in pairs to thereby modulate the potential on the high-frequency stages and, consequently, their ability to convert direct current to alternating current power.
  • Figs. 2 to 5, inclusive are modifications of the arrangement of Fig. 1.
  • the modulating circuits are shown and include means for applying more modulating potentials to a pair of the modulator tubes than to another pair.
  • Fig. 3 a pair of the modulator tubes have their input electrodes excited by the outputs of the other modulator tubes.
  • the modulating potentials are applied in somewhat the same manner in which they will apply in Fig. 3. .
  • radio-frequency chokes are interposed between the high frequency stages and the modulation potential choke.
  • the modulating potentials are applied through sub-modulators.
  • the tubes VI and V2 operate in class B and are arranged to be conductive simultaneously on the same half cycle.
  • the speech input circuits for the modulator tubes are not shown.
  • the circuit constants are such that in the carrier condition the two high frequency stagesHFl I-IF2 contribute equally to a.
  • FIG. 2 A practical circuit in which this fact is taken into account is shown in Figure 2 and comprises a direct current source HT, represented by two generators in series two high frequency stages HFI HFZ operated in class C and a choke CH all connected as in the basic circuit, and four modulator tubes operated as before in class B and designated respectively VI, VI, V2, V2.
  • HT direct current source
  • Modulation input is applied by a transformer T having a secondary S with a centre tap ST through which bias potential may, if required, be applied or which may be connected directly to earth.
  • One end of the transformer secondary is connected, if required through a negative bias source as shown, to the grid of the tube VI and the other end of the transformer secondary is connected, also through a bias source, if required to the grid of the tube V2.
  • Intermediate taps ITI, 1T2 on the transformer secondary symmetrically disposed with relation to the mid-point ST are connected, one, through a negative bias source if required to the grid of VI and the other,
  • the anodes of VIand V2 are connected to the positive terminal of the source HT and the cathodes of VI and V2 are connected at the negative terminal thereof.
  • the cathode of V2 is connected to the anode of V2 and to the point C.
  • the cathode of VI' is connected to the anode of VI and to the point B.
  • the grid of VI is connected through a negative bias source to B, and the cathode of W is connected to B; the grid of V2 is connected through a negative bias source to C and the cathode of V2 to C'.
  • the anode-cathode space of VI is connected between B and D and that of V2 between C and D.
  • Speech or other modulated input is applied through a speech transformer T whose secondary S has its ends connected respectively to the grids of VI and V2, the mid-point of the secondary being connected through a negative bias source to the point D.
  • the tube V2 and, of course, also the tube VI is controlled automatically by voltage set up in the choke CH.
  • a series circuit consisting in the order stated of a high frequency choke HFCI, a high frequency class C amplifier valve HFI, a second high frequency choke HFC2, a low frequency choke CH, a third high frequency choke HFCS, a fourth high frequency choke HFC4, and a second high frequency class C amplifier valve HFZ is connected between positive and negative terminals of a source HT of potential.
  • the anode of the valve HFI is connected through the choke HFCI to the positive terminal of the source HT and the cathode of the valve HF2 is connected direct to the negative terminal of the said source.
  • the choke CH and the choke HFC3 are two fixed condensers KI, K2.
  • the anode of HFI is capacity coupled by condenser K3 to one end and the anode of the tube HF2 is capacity coupled by condenser K4 to the other end of a parallel tuned circuit comprising an inductance L in parallel with the usual three plate condenser CP having in effect a mid-tap.
  • the mid-tap of the tuning condenser is connected to the junction point between the two fixed condensers KI, K2, and the tuned circuit inductance L is coupled to the output coil LI.
  • the low frequency choke CH is between the points B, C, and has a centre tap CHS which may be connected to earth if required, and intermediate taps B C equidistant respectively from B and C.
  • the grid of a modulating tube VI is adjustably tapped upon a resistance RI which is in series with a condenser CI and a negative bias source GBI between the point B on the one hand and the cathode of the tube VI on the other, one plate of the condenser CI being connected to B.
  • the grid of a tube V2 is adjustably tapped upon a resistance R2 which is in series with a condenser C2 and a negative bias source GB2 between C and the cathode of V2 one plate of the condenser C2 being connected to C.
  • the tube VI has its grid connected through a negative bias source to one end of the secondary S of a speech input transformer T and tube V2 has its grid connected through a negative bias source to the other end of said secondary.
  • the said secondary has a centre tap ST which is connected to the point D (this is the same as the negative terminal of the direct current potential source HT) through a negative bias source.
  • the anodes of the tubes VI and V2 are connected to the point A (the positive terminal of the direct current source HT); the cathodes of the tubes VI and V2 are connected to the point D; the anode of tube VI is connected to the cathode of tube VI and to the point B; and the anode of the valve V2 is connected to the cathode of valve V2 and to the point C.
  • Figure 5 shows a further preferred modification in which, however, sub-modulator tubes VSI and VS2 are employed, the grid potentials (both steady and varying) for the modulator tubes VI and V2 being obtained from across resistances ARI, AR2, in the anode circuits of the sub-modulators VSI VS2 respectively.
  • the grids of valves VSI VS2 are driven in phase with, but usually carry smaller amplitudes than the grids of VI and V2 respectively, 1. e. the grids of VSI VS2 are driven in phase opposition.
  • the drive may be obtained in any of a variety of ways.
  • speech input may be effected by means of a transformer having two push-pull secondaries, oneconnected between theridsjof'VJ andVZ' andthe se'cond'connected betweenlthe' grids of 'VSI andVSZ; the i centre points of the two push-pull secondaries being tiometers Pl P2 connected as shown, may be provided for adjusting the relative amplitude of the speech inputs to V5!
  • VSSIVSS2 which are fed from the speech input transformer T
  • resistance-capacity coupling effected by elements KRAI, KRAZ, and KCIKCZ.
  • batteries are shown as providing anode and grid bias voltages.
  • a battery is represented as supplying anode voltage to the sub-sub-modulators (VSSI and VSS2) and grid bias to these tubes and to the sub-modulators (VSI and VSZ).
  • any other suitable potential sources may be used with or without smoothing filters and/or potentiometer adjustment means as may be required.
  • the two high frequency tubes may operate on different wave lengths with individual high frequency input drives and, of course, individual output circuits.
  • two class C high frequency amplifiers a source of direct current potential, a modulation potential choke coil, a circuit connecting said high frequency amplifiers and said choke coil in series with the choke coil between said high frequency amplifiers, means connecting said series circuit in shunt to said direct current source, two pairs of electron discharge modulator systems each having electrodes between which impedance exists, means connecting the impedances of a pair of said electron discharge systems in series, means connecting the junction point between said last named series-connected impedances to a point on said choke coil, means connecting the said impedances of the other pair of said electron discharge systems in series, means connecting a point between the said last named series impedances to another point on said choke coil and means for modulating substantially in phase opposition the impedances of pairs of said systems at modulation potential frequency to modulate said high frequency stages on positive and negative half cycles of the modulation frequency.
  • two class C high frequency amplifier stages a source of direct current potential, a choke coil having a point thereon connected to one of said high frequency stages and a second point thereon connected to another of said high frequency stages to form with said high frequency stages a series circuit, means connecting said series circuit in shunt to said source of direct current potential, four electron discharge modulator tubes each having input electrodes and output impedances, an impedance connecting two of said electron discharge modulator tubes input electrodes in pushpull relation, means connecting points on said last named impedance to the input electrodes of the other two of said tubes to connect the input electrodes thereof in push-pull relation, means connecting one of said first two tubes in shunt to one of said high frequency stages and the other of said first two tubes in shunt to said one of said high frequency stages and said choke coil, means connecting one of said other two tubes in shunt to the other of said high frequency stages and the other of said other two tubes in shunt to said last named high frequency stage and said choke coil and means for impressing modul
  • two class 0 high frequency amplifier stages a source of direct current potential, a choke coil having a point thereon connected to one of said high frequency stages and a second point thereon connected to another of said high frequency stages to form with said high frequency stages a series circuit, means connecting said series circuit in shunt to said source of direct current potential, two pairs of electron discharge modulator tubes each having input electrodes and output impedances, an impedance connecting two of the electron discharge modulator tubes input electrodes in pushpull relation, means connecting points on said choke coil to the input electrodes of the other two of said modulator tubes, means connecting one of said first two of said tubes in shunt to one of said high frequency stages and the other of said first two tubes in shunt to said one of said high frequency stages and said choke coil, means connecting one of said other two tubes in shunt to the other of said high frequency stages and the other of said other two tubes in shunt to said last named high frequency stage and said choke coil, and means for impressing modulating potentials on said impedance

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  • Amplifiers (AREA)
  • Amplitude Modulation (AREA)
US272076A 1938-04-22 1939-05-06 Modulation system Expired - Lifetime US2243193A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB12156/38A GB515047A (en) 1938-04-22 1938-04-22 Improvements in or relating to modulator circuit arrangements for high-frequency electrical signalling

Publications (1)

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US2243193A true US2243193A (en) 1941-05-27

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US272076A Expired - Lifetime US2243193A (en) 1938-04-22 1939-05-06 Modulation system

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US (1) US2243193A (es)
FR (1) FR853324A (es)
GB (1) GB515047A (es)
NL (1) NL61000C (es)

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3021074A (en) * 1957-05-08 1962-02-13 Socony Mobil Oil Co Inc Electroic triode bridge multiplier

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FR853324A (fr) 1940-03-15
NL61000C (es)
GB515047A (en) 1939-11-24

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