US2035788A - Transmitting system - Google Patents

Transmitting system Download PDF

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Publication number
US2035788A
US2035788A US565215A US56521531A US2035788A US 2035788 A US2035788 A US 2035788A US 565215 A US565215 A US 565215A US 56521531 A US56521531 A US 56521531A US 2035788 A US2035788 A US 2035788A
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US
United States
Prior art keywords
potential
tubes
source
amplifier
output
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
US565215A
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English (en)
Inventor
Chireix Henri
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.)
Thales SA
Original Assignee
CSF Compagnie Generale de Telegraphie sans Fil SA
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Application filed by CSF Compagnie Generale de Telegraphie sans Fil SA filed Critical CSF Compagnie Generale de Telegraphie sans Fil SA
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Publication of US2035788A publication Critical patent/US2035788A/en
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Expired - Lifetime legal-status Critical Current

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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F1/00—Details of amplifiers with only discharge tubes, only semiconductor devices or only unspecified devices as amplifying elements
    • H03F1/32—Modifications of amplifiers to reduce non-linear distortion
    • H03F1/33—Modifications of amplifiers to reduce non-linear distortion in discharge-tube amplifiers

Definitions

  • This invention relates to the compensation of low-frequency distortion in radio telephony stations operating with amplification of modulated radio frequency.
  • stations working on the modulated radio frequency system are characterized by a variable current taken from the source.
  • E (t) represents the fall of potential (either positive or negative) of the high-potential source
  • Qt(1+Ef(t)) the audio frequency modulation of the radio frequency amplitude fed or applied to the grids of the last stage.
  • E by supposition is a rather small number, though not negligible compared with unity, and fit) a function capable of being resolved into a Fourier series having, for instance, 1 as its maximum value.
  • Equation (1) The second member of Equation (1) demonstrates that the compensation will be perfected to the same degree as E is negligible in reference to unity.
  • Equation (1) would be reduced to its first two terms, whence the distortion or deformation referred to at the outset.
  • Compensation most preferably is to be effected at a point where the energy level is low, that is to say, for instance, at the very point where the line comes in from the studio.
  • One particularly recommendable arrangement consists in the adoption of a symmetric assembly of tubes (pushpull scheme) for which the line currents excite the grids in opposition or push-pull fashion and the currents due to the fall of potential in addition; the output transformer, on the other hand, being connected to collect the modulation terms.
  • FIG. 1 attached to this specification by way of example illustrates a scheme embodying the foregoing idea.
  • Fig. 2 illustrates an alternate coupling arrangement for the output of tubes I-I I.
  • the line currents coming in from the studio come in at I, I and leave at 2, 2', after having passed through the push-pull arrangement indicated by the tubes I and II. Or, more precisely speaking, the input currents traverse the transformer 3 having its secondary shunted by a resistance 4 with the middle point thereof being brought out.
  • a polarization or biasing battery I0 connected with the grids of the tubes I and II is adapted to operate the latter inside a certain part of their characteristic which is known to be suitable. The operation is then as follows:
  • the current in resistance 6 will be proportional to the difference, that is v2 evidently has this form void) hence, it will be sufficient to make in order to get:
  • Equation (2) shows, what is one of the characteristic features of the present push-pull scheme, that:
  • harmonic 2 of potential '01 is also absent.
  • the amplification is correct; in other words, free from terms standing for doubled incidental frequencies or of terms meaning aggregates or differences of incidental frequencies.
  • a radio transmitter having, in combination, an oscillator, a vacuum tube modulator, and a vacuum tube amplifier, an audio frequency input circuit, a multi-tube amplifier having a pair of tubes which have their corresponding electrodes respectively interconnected, said tubes having grids polarized in such manner that each of the tubes operatesupon the knee of its characteristic, said multi-tube amplifier being connected to said audio frequency circuit and having its output connected to said modulator, a source of po- (a combination sound) tential for supplying voltage to said first vacuum tube amplifier, and means responsive to voltage variations in said source due to instantaneous variations in power of said first amplifier during a modulation cycle, said means being connected between said source and said multi-tube amplifier for changing its negative bias, whereby the audio frequency wave is distorted in a predetermined manner.
  • a radio transmitting system comprising a plurality of thermionic tube stages in cascade including a high frequency generator and a power amplifier having an output circuit, means for modulating one stage of said cascade arrangement preceding the power amplifier with audio frequencies, a source of potential for applying voltage to the plate of the power amplifier, and compensating means in circuit with said modulating means responsive to voltage variations of said source due to instantaneous variations in power of said amplifier, during the cycle of the audio frequency modulation, for impressing upon the modulated stage a voltage such that the energy in the output of said power amplifier is modulated in conformity with the impressed audio frequency modulation, said modulating means including a pair of vacuum tubes biased so that the current traversing each of them is detected, said tubes being mounted in a push pull arrangement with respect to the modulating means current and in parallel with respect to the compensating means current.
  • a radio transmitting system comprising a plurality of thermionic tube stages in cascade including a power amplifier, a source of potential for applying voltage to the plate of said power amplifier, a pair of push-pull connected tubes having input and output circuits, an audio frequency transformer, the primary winding of which is adapted to be connected to an audio frequency modulatingsource and the secondary winding of which is in said input circuit, said output circuit being coupled to a stage preceding said power amplifier, and circuit means connected to said first source of potential responsive to voltage variations of said first source due to instantaneous variations in power of said power amplifier during the cycle of an audio frequency modulation for supplying a voltage proportional to the fall of potential in said first source to said input circuit in such manner that said potential is applied to said pair of push-pull tubes in parallel.
  • a generator of local oscillations a modulator connected to said generator, a power amplifier connected to and amplifying the output of said modulator, a source of low frequency signalling potentials, an amplifier connected to said low frequency source, means connecting said low frequency amplifier to said modulator, a rectifier for supplying plate potential to said power amplifier, the output of said rectifier having an alternating current component, a low frequency alternating current circuit connected to the output of said power amplifier and coupled to said low frequency amplifier for introducing potentials into said modulator for compensating for said alternating current component.

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  • Physics & Mathematics (AREA)
  • Nonlinear Science (AREA)
  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Amplifiers (AREA)
  • Arrangements For Transmission Of Measured Signals (AREA)
US565215A 1930-09-27 1931-09-26 Transmitting system Expired - Lifetime US2035788A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
FR662574X 1930-09-27

Publications (1)

Publication Number Publication Date
US2035788A true US2035788A (en) 1936-03-31

Family

ID=9011583

Family Applications (1)

Application Number Title Priority Date Filing Date
US565215A Expired - Lifetime US2035788A (en) 1930-09-27 1931-09-26 Transmitting system

Country Status (5)

Country Link
US (1) US2035788A (enrdf_load_stackoverflow)
BE (1) BE382622A (enrdf_load_stackoverflow)
DE (1) DE662574C (enrdf_load_stackoverflow)
FR (1) FR717799A (enrdf_load_stackoverflow)
GB (1) GB375629A (enrdf_load_stackoverflow)

Also Published As

Publication number Publication date
FR717799A (fr) 1932-01-14
GB375629A (en) 1932-06-30
DE662574C (de) 1938-07-19
BE382622A (enrdf_load_stackoverflow)

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