EP1671345A2 - Amplifier comprising an electronic tube provided with collectors - Google Patents

Amplifier comprising an electronic tube provided with collectors

Info

Publication number
EP1671345A2
EP1671345A2 EP04766881A EP04766881A EP1671345A2 EP 1671345 A2 EP1671345 A2 EP 1671345A2 EP 04766881 A EP04766881 A EP 04766881A EP 04766881 A EP04766881 A EP 04766881A EP 1671345 A2 EP1671345 A2 EP 1671345A2
Authority
EP
European Patent Office
Prior art keywords
collector
voltage source
voltage
cathode
collectors
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.)
Withdrawn
Application number
EP04766881A
Other languages
German (de)
French (fr)
Inventor
Claude Thales Intellectual Property BEL
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
Thales SA
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
Application filed by Thales SA filed Critical Thales SA
Publication of EP1671345A2 publication Critical patent/EP1671345A2/en
Withdrawn legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J23/00—Details of transit-time tubes of the types covered by group H01J25/00
    • H01J23/02—Electrodes; Magnetic control means; Screens
    • H01J23/027—Collectors
    • H01J23/0275—Multistage collectors
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J23/00—Details of transit-time tubes of the types covered by group H01J25/00
    • H01J23/02—Electrodes; Magnetic control means; Screens
    • H01J23/027—Collectors
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J23/00—Details of transit-time tubes of the types covered by group H01J25/00
    • H01J23/34—Circuit arrangements not adapted to a particular application of the tube and not otherwise provided for
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J25/00—Transit-time tubes, e.g. klystrons, travelling-wave tubes, magnetrons
    • H01J25/02—Tubes with electron stream modulated in velocity or density in a modulator zone and thereafter giving up energy in an inducing zone, the zones being associated with one or more resonators
    • H01J25/04—Tubes having one or more resonators, without reflection of the electron stream, and in which the modulation produced in the modulator zone is mainly density modulation, e.g. Heaff tube
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/14—Relay systems
    • H04B7/15—Active relay systems
    • H04B7/155—Ground-based stations

Definitions

  • An amplifier includes an electron beam electron tube and voltage sources; the tube comprises at least two collectors, each collector being connected to a voltage source.
  • the field of the invention is that of power amplification of UHF signals, in particular the amplification of analog and digital television signals from terrestrial transmitters, by means of vacuum tubes comprising an axial electron beam. It is briefly recalled that a vacuum tube uses the principle of interaction between an electron beam and an electromagnetic wave, to transmit to the wave part of the energy contained in the electron beam, so as to obtain at the outlet of the tube a wave of energy greater than that of the wave injected at the inlet of the tube. There are several categories of vacuum tubes.
  • TOP traveling wave tubes
  • IOT inductive Output Tube
  • IOT shown in Figure 1. It comprises an elongated vacuum enclosure partly made up of several insulating ceramics 23a, 23b, 23c, 23d, with at one first end an electron gun emitting an electron beam 12 and, at a second end, a first collector 14a and a second collector 14b.
  • the electron gun includes a cathode 16 which emits the electrons and a grid 18 which controls the flow of electrons as a function of the voltage applied to it.
  • the signal to be amplified with power Pe is injected between the cathode 16 and the grid 18 and thus modulates the voltage of the grid.
  • the electron beam 12 which crosses the grid is then modulated in density by the grid and the electrons are emitted in the form of packets; the duration between two packets is equal to the signal period.
  • the beam 12 represented in the form of electron packets is substantially cylindrical over almost the entire length of the tube between the cathode 16 and the collectors 14a and 14b. This cylindrical shape is obtained thanks on the one hand to the shape of the cathode 16, the anode 24 and the grid 18 and on the other hand thanks to an axial magnetic field which keeps the electrons close to the axis 10 of the tube.
  • a packet of electrons coming from the grid is accelerated before entering a sliding tube 20 then in an interaction space located between two interaction nozzles 22a, 22b; this interaction space is connected to a primary output cavity 26 in which it generates an electric field.
  • this interaction space When another packet of electrons reaches this interaction space, it encounters this electric field which slows it down.
  • the kinetic energy of the electrons is converted into electromagnetic or microwave energy, that is to say into output power Ps which is directed to use for example by a coaxial through an insulator 25.
  • the energy efficiency is generally around 20 to 40%: it characterizes the part of the energy of the electron beam converted into energy in the amplified signal.
  • the energy remaining in the electron beam after it has passed through the primary output cavity 26 is then dissipated in the collector.
  • the electrons then bombard the walls of the collector and transform their kinetic energy into heat.
  • the electrons that reach the collector have very variable energy levels.
  • the collector is divided into two collectors 14a and 14b electrically insulated; each of these collectors is brought to a potential corresponding to one of the energy levels of the electrons.
  • the second collector 14b is brought to a lower potential than the first 14a, relative to the cathode 16 in order to slow down the electrons which strike this collector and thus reduce the loss of energy in the form of heat. We can thus obtain a yield up to three times higher than the yield of a conventional tube.
  • Tubes comprising more than two collectors have already been produced, as have tubes comprising a repelling electrode at the bottom of the collector, this electrode being generally connected to the cathode.
  • the collector 14b is connected to the positive pole 28 of a DC voltage source 30, for example of 26 kV.
  • the negative pole 32 of the DC voltage source 30 is connected to the cathode 16.
  • the collector 14a is connected to the positive pole 34 of a DC voltage source 36, for example of 34 kV.
  • the negative pole of the DC voltage source 36 common to that of the voltage source 30, is also connected to the cathode 16.
  • the two sources therefore have a common point 32 located at the cathode.
  • the output cavity 26 is also connected to the positive pole 34 of the DC voltage source 36, possibly through a measurement shunt between the mass 17 and the body of the tube which includes the anode 24 and the two interaction nozzles; this measurement shunt measures the current intercepted by the body.
  • the outlet cavity 26 is connected to ground.
  • a current I of a few amperes (for example 2.5 A) is obtained from cathode 16 in the electron beam 12.
  • two bulky and expensive voltage sources 30 and 36 are used. given the value of their voltage, the distances required for their isolation as well as their respective powers.
  • the potential difference between the two collectors 14a and 14b also known as vacuum voltage, must not exceed 12 kV under penalty of damaging the tube, in particular the ceramic 23a located between the two collectors.
  • this type of voltage source when one is cut quickly by the action of the safety devices or is established more quickly than the other when the power is applied, a differential voltage of up to 34 kV is established between the two collectors 14a and 14b causing possibly irreversible damage.
  • the need to synchronize these voltage sources makes this configuration very restrictive.
  • An important object of the invention is therefore to overcome these drawbacks by modifying the way of supplying the collectors and the cathode.
  • the invention provides an amplifier comprising an electronic tube with an axial electron beam, with a cathode and at least two collectors, the amplifier further comprising at least two DC voltage sources, each collector being connected to a DC voltage source with a potential difference such that the further the collector is from the cathode, the smaller the potential difference between this collector and the cathode, characterized in that the DC voltage sources are connected together at a point. common located at the collector whose potential difference with the cathode is the smallest but not zero.
  • This configuration thus makes it possible to use voltage sources of lower value than in the prior art and to minimize the size and the cost of the voltage sources.
  • the voltage sources are variable.
  • the voltage source (s) defining a vacuum voltage between two collectors is a drawdown voltage source.
  • the use of this voltage source with drawdown is particularly indicated for the amplification of variable average power signals as in the case of analog television.
  • the invention also relates to a transmitter comprising such an amplifier.
  • FIG. 1 already described schematically represents an amplifier with a tube electronic with inductive output comprising two collectors and with voltage sources arranged according to the prior art
  • FIG. 2 schematically represents an amplifier with an electronic tube with inductive output comprising two collectors and with voltage sources arranged according to the invention
  • FIG. 3 schematically represents an amplifier with an electronic tube with inductive output comprising three collectors and with voltage sources arranged according to the invention. From one figure to another, the same references are used to designate the same elements.
  • FIG. 2 represents an exemplary embodiment of an amplifier implementing the invention; it includes an electronic tube with inductive output with at least two collectors. It comprises two collectors 14a and 14b in the example in the figure.
  • the invention also applies with traveling wave tubes or klystrons and more generally with any electronic tube with an axial electron beam.
  • the collector 14b is connected to the positive pole 28 of a DC voltage source 30, for example of 26 kV.
  • the negative pole of the DC voltage source 30 is connected to the cathode 16.
  • the collector 14a is connected to the positive pole 34 of a DC voltage source 36 ', for example of 8 kV.
  • the negative pole of this voltage source 36 ' is connected to the collector 14b; it is in series with the voltage source 30.
  • the common point 32 of these two voltage sources 36 ′ and 30 is at the level of the collector 14b, that is to say of the one which is furthest from the cathode.
  • the output cavity 26 is also connected to the positive pole 34 of the DC voltage source 36 ', possibly by a measurement shunt.
  • This configuration thus makes it possible to use a voltage source of 26 kV and a voltage source of low value for example of 8 kV instead of the voltage sources of 34 kV and 26 kV used in the example presented in FIG. 1.
  • the low value of the voltage source 36 ' makes it possible to use a compact model which minimizes the size of new transmitters and makes it possible at low cost to incorporate the tube into existing transmitters.
  • the potential difference between the two collectors 14a and 14b that is to say the vacuum voltage cannot exceed the voltage of this source 36 ', in this case 8 kV, when it could reach 34 kV in the example of FIG. 1.
  • the vacuum voltage is that of the voltage source 36 ', ie 8 kV and when the voltage source 36' is cut, the vacuum voltage is zero. It is therefore no longer essential to synchronize the switching on and off of the voltage sources because in any case the potential difference between the collectors cannot exceed that of the low value voltage source. This improves the reliability of this type of material and preserves the tube.
  • a low voltage source 36 ′ is used for this low voltage source 36 ′.
  • a voltage source with drawdown is a stabilized and bounded voltage source with a voltage setpoint and a current setpoint: the voltage source provides the highest possible voltage so that at least one of these setpoints be reached.
  • a drawdown voltage source is used which makes it possible to avoid overdissipation of this collector.
  • the use of this voltage source with drawdown is particularly indicated for the amplification of variable average power signals as in the case of analog television. In this case, in fact, the amplitude modulation of the carrier of the analog signal results in a modulation of the current of the signal to be amplified which is reflected on the current obtained in this collector 14a.
  • FIG. 3 shows an exemplary embodiment of the invention in the case of a tube comprising a third manifold 14c in addition to the two collectors 14a and 14b of the previous figure.
  • the electrical configuration is the same as in the example in FIG. 2, with in addition a DC voltage source 38, for example 6 kV, to the positive pole to which the collector 14c is connected.
  • the negative pole of this voltage source 38 is connected to the collector 14b.
  • This DC voltage source 38 is in series with the voltage source 30.
  • the point 32 common to the three voltage sources 38, 36 'and 30 is located at the collector 14b, that is to say the one which is farthest from the cathode.
  • the overall voltage source for the collector 14c is 26 kV + 6 kV or 32 kV.
  • the potential difference between the two collectors 14c and 14b, that is to say the vacuum voltage cannot exceed the voltage of this source 38, in this case 6 kV.
  • the invention applies to other frequency bands than the UHF band such as for example the frequency bands L (from 1 to 2 GHz), S (from 2 to 4 GHz), C (from 4 to 8 GHz) , X (from 8 to 12.4 GHz), Ku (from 12.4 to 18 GHz), K (from 18 to 26.5 GHz), Ka (from 26.5 to 40 GHz), etc.
  • the invention also relates to a transmitter comprising such an amplifier. It is for example a terrestrial transmitter of analog or digital television signals.

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Amplifiers (AREA)

Abstract

The invention relates to an amplifier comprising an axial electron beam electronic tube provided with a cathode (16) and at least to collectors (14a, 14b) and at least two continuous voltage sources. Each collector (14a, 14b) is connected to the continuous voltage source whose potential difference is directly proportional to the distance between the collector and the cathode. Said invention is characterised in that the voltage sources are interconnected at a common point (32) which is arranged near the collector (14b) whose potential difference is lower than the potential difference of the other collector but is higher than zero.

Description

AMPLIFICATEUR AVEC TUBE ELECTRONIQUE A COLLECTEURS AMPLIFIER WITH ELECTRONIC TUBE WITH MANIFOLDS
L'invention concerne un amplificateur qui comprend un tube électronique à faisceau d'électrons axial et des sources de tension ; le tube comporte au moins deux collecteurs, chaque collecteur étant relié à une source de tension. Le domaine de l'invention est celui de l'amplification de puissance de signaux UHF, en particulier l'amplification des signaux de télévision analogique et numérique des émetteurs terrestres, au moyen de tubes à vide comportant un faisceau d'électrons axial. On rappelle sommairement qu'un tube à vide utilise le principe de l'interaction entre un faisceau d'électrons et une onde électromagnétique, pour transmettre à l'onde une partie de l'énergie contenue dans le faisceau d'électrons, de manière à obtenir en sortie du tube une onde d'énergie plus grande que celle de l'onde injectée à l'entrée du tube. II existe plusieurs catégories de tubes à vide. Dans les tubes à ondes progressives (« TOP » ou «TWT » pour Traveling Wave Tube en anglais) et les klystrons, le faisceau d'électrons est modulé en vitesse. Dans les tubes à sortie inductive (« IOT » ou « Inductive Output Tube » en anglais) il est modulé en densité. On va décrire le principe de cette interaction appliqué à un tubeAn amplifier includes an electron beam electron tube and voltage sources; the tube comprises at least two collectors, each collector being connected to a voltage source. The field of the invention is that of power amplification of UHF signals, in particular the amplification of analog and digital television signals from terrestrial transmitters, by means of vacuum tubes comprising an axial electron beam. It is briefly recalled that a vacuum tube uses the principle of interaction between an electron beam and an electromagnetic wave, to transmit to the wave part of the energy contained in the electron beam, so as to obtain at the outlet of the tube a wave of energy greater than that of the wave injected at the inlet of the tube. There are several categories of vacuum tubes. In traveling wave tubes (“TOP” or “TWT” for Traveling Wave Tube in English) and klystrons, the electron beam is modulated in speed. In the tubes with inductive output (“IOT” or “Inductive Output Tube” in English) it is modulated in density. We will describe the principle of this interaction applied to a tube
« IOT » représenté figure 1 . Il comporte une enceinte à vide allongée en partie constituée de plusieurs céramiques d'isolation 23a, 23b, 23c, 23d, avec à une première extrémité un canon à électrons émettant un faisceau d'électrons 12 et, à une deuxième extrémité, un premier collecteur 14a et un deuxième collecteur 14b. Le canon à électrons comprend une cathode 16 qui émet les électrons et une grille 18 qui contrôle le flux des électrons en fonction de la tension qui lui est appliquée. Le signal à amplifier de puissance Pe est injecté entre la cathode 16 et la grille 18 et module ainsi la tension de la grille. Le faisceau d'électrons 12 qui traverse la grille est alors modulé en densité par la grille et les électrons sont émis sous forme de paquets ; la durée entre deux paquets est égale à la période du signal. Le faisceau 12 représenté sous forme de paquets d'électrons, est sensiblement cylindrique sur presque toute la longueur du tube entre la cathode 16 et les collecteurs 14a et 14b. Cette forme cylindrique est obtenue grâce d'une part à la forme de la cathode 16, de l'anode 24 et de la grille 18 et d'autre part grâce à un champ magnétique axial qui maintient les électrons près de l'axe 10 du tube. Un paquet d'électrons provenant de la grille est accéléré avant d'entrer dans un tube de glissement 20 puis dans un espace d'interaction situé entre deux becs d'interaction 22a, 22b ; cet espace d'interaction est relié à une cavité primaire de sortie 26 dans laquelle il génère un champ électrique. Quand un autre paquet d'électrons atteint cet espace d'interaction, il rencontre ce champ électrique qui le freine. Lors de ce freinage, l'énergie cinétique des électrons est convertie en énergie électromagnétique ou hyperfréquence, c'est-à-dire en puissance de sortie Ps qui est dirigée vers l'utilisation par exemple par un coaxial à travers un isolant 25. Pour un signal de télévision, le rendement énergétique est généralement de l'ordre de 20 à 40 % : il caractérise la partie de l'énergie du faisceau d'électrons convertie en énergie dans le signal amplifié. L'énergie restante dans le faisceau d'électrons après son passage dans la cavité primaire de sortie 26 est ensuite dissipée dans le collecteur. Les électrons bombardent alors les parois du collecteur et transforment leur énergie cinétique en chaleur. Les électrons qui atteignent le collecteur ont des niveaux d'énergie très variables. Afin d'améliorer le rendement énergétique de ces tubes, le collecteur est divisé en deux collecteurs 14a et 14b isolés électriquement ; chacun de ces collecteurs est porté à un potentiel correspondant à un des niveaux d'énergie des électrons. Le deuxième collecteur 14b est porté à un potentiel plus faible que le premier 14a, par rapport à la cathode 16 afin de ralentir les électrons qui percutent ce collecteur et ainsi diminuer la perte d'énergie sous forme de chaleur. On peut ainsi obtenir un rendement jusqu'à trois fois supérieur au rendement d'un tube conventionnel. Des tubes comportant plus de deux collecteurs ont déjà été réalisés de même que des tubes comportant une électrode repousseuse en fond de collecteur, cette électrode étant généralement connectée à la cathode. Le collecteur 14b est raccordé au pôle positif 28 d'une source de tension continue 30, par exemple de 26 kV. Le pôle négatif 32 de la source de tension continue 30 est raccordé à la cathode 16. Le collecteur 14a est raccordé au pôle positif 34 d'une source de tension continue 36, par exemple de 34 kV. Le pôle négatif de la source de tension continue 36, commun à celui de la source de tension 30, est également raccordé à la cathode 16. Les deux sources ont donc un point commun 32 situé au niveau de la cathode. La cavité de sortie 26 est également raccordée au pôle positif 34 de la source de tension continue 36, éventuellement à travers un shunt de mesure entre la masse 17 et le corps du tube qui comprend l'anode 24 et les deux becs d'interaction ; ce shunt de mesure permet de mesurer le courant intercepté par le corps. La cavité de sortie 26 est raccordée à la masse. On obtient un courant I de quelques Ampères (par exemple 2.5 A) issu de la cathode 16 dans le faisceau d'électrons 12. Selon cette configuration, on utilise deux sources de tension 30 et 36 de plus de 26 kV, encombrantes et onéreuses compte tenu de la valeur de leur tension, des distances nécessaires à leur isolement ainsi que de leurs puissances respectives. En outre la différence de potentiel entre les deux collecteurs 14a et 14b, aussi dénommée tension de dépression, ne doit pas excéder 12 kV sous peine d'endommager le tube, notamment la céramique 23a située entre les deux collecteurs. Or, dans ce type de source de tension, lorsque l'une est coupée rapidement par l'action des sécurités ou s'établit plus rapidement que l'autre lors de la mise sous tension, une tension différentielle pouvant atteindre 34 kV s'établit entre les deux collecteurs 14a et 14b provoquant des dommages éventuellement irréversibles. La nécessité de synchroniser ces sources de tension rend cette configuration très contraignante. Un but important de l'invention est donc de pallier ces inconvénients en modifiant la façon d'alimenter les collecteurs et la cathode. Pour atteindre ce but, l'invention propose un amplificateur comportant un tube électronique à faisceau d'électrons axial, avec une cathode et au moins deux collecteurs, l'amplificateur comportant en outre au moins deux sources de tension continue, chaque collecteur étant relié à une source de tension continue présentant une différence de potentiel telle que plus le collecteur est éloigné de la cathode, plus la différence de potentiel entre ce collecteur et la cathode est faible, caractérisé en ce que les sources de tension continue sont raccordées entre elles en un point commun situé au niveau du collecteur dont la différence de potentiel avec la cathode est la plus faible mais non nulle. Cette configuration permet ainsi d'utiliser des sources de tension de plus faible valeur que dans l'art antérieur et de minimiser l'encombrement et le coût des sources de tension. En outre, il n'est plus indispensable de synchroniser la mise en marche et les coupures des sources de tension car en aucun cas la différence de potentiel entre les collecteurs ne peut excéder celle de la source de tension de faible valeur. Ceci améliore la fiabilité de ce type de matériel et préserve le tube. Selon une caractéristique de l'invention, les sources de tension sont variables. De préférence, la (ou les) source(s) de tension définissant une tension de dépression entre deux collecteurs, est une source de tension à rabattement. L'utilisation de cette source de tension à rabattement est particulièrement indiquée pour l'amplification de signaux de puissance moyenne variable comme dans le cas de la télévision analogique. L'invention a aussi pour objet un émetteur comportant un tel amplificateur. D'autres caractéristiques et avantages de l'invention apparaîtront à la lecture de la description détaillée qui suit, faite à titre d'exemple non limitatif et en référence aux dessins annexés dans lequels : la figure 1 déjà décrite représente schématiquement un amplificateur avec un tube électronique à sortie inductive comportant deux collecteurs et avec des sources de tension disposées selon l'art antérieur, la figure 2 représente schématiquement un amplificateur avec un tube électronique à sortie inductive comportant deux collecteurs et avec des sources de tension disposées selon l'invention, la figure 3 représente schématiquement un amplificateur avec un tube électronique à sortie inductive comportant trois collecteurs et avec des sources de tension disposées selon l'invention. D'une figure à l'autre, les mêmes références sont utilisées pour désigner les mêmes éléments. La figure 2 représente un exemple de réalisation d'un amplificateur mettant en œuvre l'invention ; il comprend un tube électronique à sortie inductive avec au moins deux collecteurs. Il comporte deux collecteurs 14a et 14b dans l'exemple de la figure. L'invention s'applique également avec des tubes à ondes progressives ou des klystrons et plus généralement avec tout tube électronique à faisceau d'électrons axial. Le collecteur 14b est raccordé au pôle positif 28 d'une source de tension continue 30, par exemple de 26 kV. Le pôle négatif de la source de tension continue 30 est raccordé à la cathode 16. Le collecteur 14a est raccordé au pôle positif 34 d'une source de tension continue 36', par exemple de 8 kV. Le pôle négatif de cette source de tension 36' est raccordé au collecteur 14b ; elle est en série avec la source de tension 30. Le point commun 32 de ces deux sources de tension 36' et 30 est au niveau du collecteur 14b, c'est-à-dire de celui qui est le plus éloigné de la cathode. La cavité de sortie 26 est également raccordée au pôle positif 34 de la source de tension continue 36', éventuellement par un shunt de mesure. On retrouve bien une source de tension globale pour le collecteur 14a de 26 kV + 8 kV soit 34 kV. Cette configuration permet ainsi d'utiliser une source de tension de 26 kV et une source de tension de faible valeur par exemple de 8 kV au lieu des sources de tension de 34 kV et 26 kV utilisées dans l'exemple présenté figure 1. La faible valeur de la source de tension 36' permet d'utiliser un modèle compact qui minimise l'encombrement des émetteurs neufs et rend possible à moindre coût l'incorporation du tube dans des émetteurs existants. De plus, la différence de potentiel entre les deux collecteurs 14a et 14b, c'est-à-dire la tension de dépression ne peut excéder la tension de cette source 36', en l'occurrence 8 kV, alors qu'elle pouvait atteindre 34 kV dans l'exemple de la figure 1. En effet, lorsque la source de tension 30 est coupée, la tension de dépression est celle de la source de tension 36', soit 8 kV et lorsque la source de tension 36' est coupée, la tension de dépression est nulle. Il n'est donc plus indispensable de synchroniser la mise en marche et les coupures des sources de tension car en aucun cas la différence de potentiel entre les collecteurs ne peut excéder celle de la source de tension de faible valeur. Ceci améliore la fiabilité de ce type de matériel et préserve le tube. On utilise de préférence pour cette source de tension de faible valeur 36' une source de tension à rabattement. On rappelle qu'une source de tension à rabattement est une source de tension stabilisée et bornée avec une consigne en tension et une consigne en courant : la source de tension fournit la tension la plus élevée possible pour que l'une au moins de ces consignes soit atteinte. Ainsi, en fonction du courant maximal admissible par le collecteur 14a, on utilise une source de tension à rabattement permettant d'éviter une surdissipation de ce collecteur. L'utilisation de cette source de tension à rabattement est particulièrement indiquée pour l'amplification de signaux de puissance moyenne variable comme dans le cas de la télévision analogique. Dans ce cas en effet, la modulation d'amplitude de la porteuse du signal analogique se traduit par une modulation du courant du signal à amplifier qui se répercute sur le courant obtenu dans ce collecteur 14a. En cas de rabattement de la source de tension 36', c'est-à-dire en cas de rabattement de la tension de dépression, la source de tension 30 est de préférence asservie par une consigne établie par la mesure de tension cathode 16-masse 17 afin de maintenir cette tension constante. On a représenté figure 3 un exemple de réalisation de l'invention dans le cas d'un tube comportant un troisième collecteur 14c en plus des deux collecteurs 14a et 14b de la figure précédente. La configuration électrique est la même que dans l'exemple de la figure 2, avec en plus une source de tension continue 38 par exemple de 6 kV, au pôle positif de laquelle le collecteur 14c est raccordé. Le pôle négatif de cette source de tension 38 est raccordé au collecteur 14b. Cette source de tension continue 38 est en série avec la source de tension 30. Le point 32 commun aux trois sources de tension 38, 36' et 30 est situé au niveau du collecteur 14b, c'est- à-dire de celui qui est le plus éloigné de la cathode. La source de tension globale pour le collecteur 14c est de 26 kV + 6 kV soit 32 kV. La différence de potentiel entre les deux collecteurs 14c et 14b, c'est-à-dire la tension de dépression ne peut excéder la tension de cette source 38, en l'occurrence 6 kV. On peut également utiliser pour cette source de tension de faible valeur 38, une source de tension à rabattement. L'invention s'applique à d'autres bandes de fréquences que la bande UHF comme par exemple les bandes de fréquences L (de 1 à 2 GHz), S (de 2 à 4 GHz), C (de 4 à 8 GHz), X (de 8 à 12.4 GHz), Ku (de 12.4 à 18 GHz), K (de 18 à 26.5 GHz), Ka (de 26.5 à 40 GHz), etc. L'invention a aussi pour objet un émetteur comportant un tel amplificateur. Il s'agit par exemple d'un émetteur terrestre de signaux de télévision analogiques ou numériques. "IOT" shown in Figure 1. It comprises an elongated vacuum enclosure partly made up of several insulating ceramics 23a, 23b, 23c, 23d, with at one first end an electron gun emitting an electron beam 12 and, at a second end, a first collector 14a and a second collector 14b. The electron gun includes a cathode 16 which emits the electrons and a grid 18 which controls the flow of electrons as a function of the voltage applied to it. The signal to be amplified with power Pe is injected between the cathode 16 and the grid 18 and thus modulates the voltage of the grid. The electron beam 12 which crosses the grid is then modulated in density by the grid and the electrons are emitted in the form of packets; the duration between two packets is equal to the signal period. The beam 12 represented in the form of electron packets, is substantially cylindrical over almost the entire length of the tube between the cathode 16 and the collectors 14a and 14b. This cylindrical shape is obtained thanks on the one hand to the shape of the cathode 16, the anode 24 and the grid 18 and on the other hand thanks to an axial magnetic field which keeps the electrons close to the axis 10 of the tube. A packet of electrons coming from the grid is accelerated before entering a sliding tube 20 then in an interaction space located between two interaction nozzles 22a, 22b; this interaction space is connected to a primary output cavity 26 in which it generates an electric field. When another packet of electrons reaches this interaction space, it encounters this electric field which slows it down. During this braking, the kinetic energy of the electrons is converted into electromagnetic or microwave energy, that is to say into output power Ps which is directed to use for example by a coaxial through an insulator 25. For a television signal, the energy efficiency is generally around 20 to 40%: it characterizes the part of the energy of the electron beam converted into energy in the amplified signal. The energy remaining in the electron beam after it has passed through the primary output cavity 26 is then dissipated in the collector. The electrons then bombard the walls of the collector and transform their kinetic energy into heat. The electrons that reach the collector have very variable energy levels. In order to improve the energy efficiency of these tubes, the collector is divided into two collectors 14a and 14b electrically insulated; each of these collectors is brought to a potential corresponding to one of the energy levels of the electrons. The second collector 14b is brought to a lower potential than the first 14a, relative to the cathode 16 in order to slow down the electrons which strike this collector and thus reduce the loss of energy in the form of heat. We can thus obtain a yield up to three times higher than the yield of a conventional tube. Tubes comprising more than two collectors have already been produced, as have tubes comprising a repelling electrode at the bottom of the collector, this electrode being generally connected to the cathode. The collector 14b is connected to the positive pole 28 of a DC voltage source 30, for example of 26 kV. The negative pole 32 of the DC voltage source 30 is connected to the cathode 16. The collector 14a is connected to the positive pole 34 of a DC voltage source 36, for example of 34 kV. The negative pole of the DC voltage source 36, common to that of the voltage source 30, is also connected to the cathode 16. The two sources therefore have a common point 32 located at the cathode. The output cavity 26 is also connected to the positive pole 34 of the DC voltage source 36, possibly through a measurement shunt between the mass 17 and the body of the tube which includes the anode 24 and the two interaction nozzles; this measurement shunt measures the current intercepted by the body. The outlet cavity 26 is connected to ground. A current I of a few amperes (for example 2.5 A) is obtained from cathode 16 in the electron beam 12. According to this configuration, two bulky and expensive voltage sources 30 and 36 are used. given the value of their voltage, the distances required for their isolation as well as their respective powers. In addition, the potential difference between the two collectors 14a and 14b, also known as vacuum voltage, must not exceed 12 kV under penalty of damaging the tube, in particular the ceramic 23a located between the two collectors. However, in this type of voltage source, when one is cut quickly by the action of the safety devices or is established more quickly than the other when the power is applied, a differential voltage of up to 34 kV is established between the two collectors 14a and 14b causing possibly irreversible damage. The need to synchronize these voltage sources makes this configuration very restrictive. An important object of the invention is therefore to overcome these drawbacks by modifying the way of supplying the collectors and the cathode. To achieve this object, the invention provides an amplifier comprising an electronic tube with an axial electron beam, with a cathode and at least two collectors, the amplifier further comprising at least two DC voltage sources, each collector being connected to a DC voltage source with a potential difference such that the further the collector is from the cathode, the smaller the potential difference between this collector and the cathode, characterized in that the DC voltage sources are connected together at a point. common located at the collector whose potential difference with the cathode is the smallest but not zero. This configuration thus makes it possible to use voltage sources of lower value than in the prior art and to minimize the size and the cost of the voltage sources. In addition, it is no longer essential to synchronize the switching on and off of the voltage sources, because in any case the potential difference between the collectors cannot exceed that of the low value voltage source. This improves the reliability of this type of material and preserves the tube. According to a characteristic of the invention, the voltage sources are variable. Preferably, the voltage source (s) defining a vacuum voltage between two collectors is a drawdown voltage source. The use of this voltage source with drawdown is particularly indicated for the amplification of variable average power signals as in the case of analog television. The invention also relates to a transmitter comprising such an amplifier. Other characteristics and advantages of the invention will appear on reading the detailed description which follows, given by way of nonlimiting example and with reference to the appended drawings in which: FIG. 1 already described schematically represents an amplifier with a tube electronic with inductive output comprising two collectors and with voltage sources arranged according to the prior art, FIG. 2 schematically represents an amplifier with an electronic tube with inductive output comprising two collectors and with voltage sources arranged according to the invention, FIG. 3 schematically represents an amplifier with an electronic tube with inductive output comprising three collectors and with voltage sources arranged according to the invention. From one figure to another, the same references are used to designate the same elements. FIG. 2 represents an exemplary embodiment of an amplifier implementing the invention; it includes an electronic tube with inductive output with at least two collectors. It comprises two collectors 14a and 14b in the example in the figure. The invention also applies with traveling wave tubes or klystrons and more generally with any electronic tube with an axial electron beam. The collector 14b is connected to the positive pole 28 of a DC voltage source 30, for example of 26 kV. The negative pole of the DC voltage source 30 is connected to the cathode 16. The collector 14a is connected to the positive pole 34 of a DC voltage source 36 ', for example of 8 kV. The negative pole of this voltage source 36 'is connected to the collector 14b; it is in series with the voltage source 30. The common point 32 of these two voltage sources 36 ′ and 30 is at the level of the collector 14b, that is to say of the one which is furthest from the cathode. The output cavity 26 is also connected to the positive pole 34 of the DC voltage source 36 ', possibly by a measurement shunt. There is indeed a global voltage source for the collector 14a of 26 kV + 8 kV or 34 kV. This configuration thus makes it possible to use a voltage source of 26 kV and a voltage source of low value for example of 8 kV instead of the voltage sources of 34 kV and 26 kV used in the example presented in FIG. 1. The low value of the voltage source 36 'makes it possible to use a compact model which minimizes the size of new transmitters and makes it possible at low cost to incorporate the tube into existing transmitters. In addition, the potential difference between the two collectors 14a and 14b, that is to say the vacuum voltage cannot exceed the voltage of this source 36 ', in this case 8 kV, when it could reach 34 kV in the example of FIG. 1. Indeed, when the voltage source 30 is cut, the vacuum voltage is that of the voltage source 36 ', ie 8 kV and when the voltage source 36' is cut, the vacuum voltage is zero. It is therefore no longer essential to synchronize the switching on and off of the voltage sources because in any case the potential difference between the collectors cannot exceed that of the low value voltage source. This improves the reliability of this type of material and preserves the tube. Preferably, a low voltage source 36 ′ is used for this low voltage source 36 ′. Recall that a voltage source with drawdown is a stabilized and bounded voltage source with a voltage setpoint and a current setpoint: the voltage source provides the highest possible voltage so that at least one of these setpoints be reached. Thus, as a function of the maximum current admissible by the collector 14a, a drawdown voltage source is used which makes it possible to avoid overdissipation of this collector. The use of this voltage source with drawdown is particularly indicated for the amplification of variable average power signals as in the case of analog television. In this case, in fact, the amplitude modulation of the carrier of the analog signal results in a modulation of the current of the signal to be amplified which is reflected on the current obtained in this collector 14a. In the event of the voltage source 36 'being turned down, that is to say in the event of the depression voltage being turned down, the voltage source 30 is preferably controlled by a set point established by the cathode voltage measurement 16- mass 17 in order to maintain this constant tension. FIG. 3 shows an exemplary embodiment of the invention in the case of a tube comprising a third manifold 14c in addition to the two collectors 14a and 14b of the previous figure. The electrical configuration is the same as in the example in FIG. 2, with in addition a DC voltage source 38, for example 6 kV, to the positive pole to which the collector 14c is connected. The negative pole of this voltage source 38 is connected to the collector 14b. This DC voltage source 38 is in series with the voltage source 30. The point 32 common to the three voltage sources 38, 36 'and 30 is located at the collector 14b, that is to say the one which is farthest from the cathode. The overall voltage source for the collector 14c is 26 kV + 6 kV or 32 kV. The potential difference between the two collectors 14c and 14b, that is to say the vacuum voltage cannot exceed the voltage of this source 38, in this case 6 kV. One can also use for this low value voltage source 38, a drawdown voltage source. The invention applies to other frequency bands than the UHF band such as for example the frequency bands L (from 1 to 2 GHz), S (from 2 to 4 GHz), C (from 4 to 8 GHz) , X (from 8 to 12.4 GHz), Ku (from 12.4 to 18 GHz), K (from 18 to 26.5 GHz), Ka (from 26.5 to 40 GHz), etc. The invention also relates to a transmitter comprising such an amplifier. It is for example a terrestrial transmitter of analog or digital television signals.

Claims

REVENDICATIONS
1. Amplificateur comportant un tube électronique à faisceau d'électrons axial, avec une cathode (16) et au moins deux collecteurs (14a, 14b), l'amplificateur comportant en outre au moins deux sources de tension continue, chaque collecteur (14a, 14b) étant relié à une source de tension continue présentant une différence de potentiel telle que plus le collecteur est éloigné de la cathode, plus la différence de potentiel entre ce collecteur et la cathode est faible, caractérisé en ce que les sources de tension continue sont raccordées entre elles en un point commun (32) situé au niveau du collecteur (14b) dont la différence de potentiel avec la cathode est la plus faible mais non nulle.1. Amplifier comprising an electronic tube with an axial electron beam, with a cathode (16) and at least two collectors (14a, 14b), the amplifier further comprising at least two sources of DC voltage, each collector (14a, 14b) being connected to a DC voltage source having a potential difference such that the further the collector is away from the cathode, the smaller the potential difference between this collector and the cathode, characterized in that the DC voltage sources are connected together at a common point (32) located at the collector (14b) whose potential difference with the cathode is the smallest but not zero.
2. Amplificateur selon la revendication précédente, caractérisé en ce que les sources de tension (30, 36') sont variables.2. Amplifier according to the preceding claim, characterized in that the voltage sources (30, 36 ') are variable.
3. Amplificateur selon l'une des revendications précédentes, caractérisé en ce que la (ou les) source(s) de tension (36') définissant une tension de dépression entre deux collecteurs (14a, 14b), est une source de tension à rabattement.3. Amplifier according to one of the preceding claims, characterized in that the voltage source (s) (36 ') defining a vacuum voltage between two collectors (14a, 14b), is a voltage source at drawdown.
4. Amplificateur selon la revendication précédente, caractérisé en ce qu'il comporte des moyens d'asservissement de la source de tension (30) située entre le point commun (32) et la cathode (16) afin de maintenir constante la source de tension (30) en cas de rabattement de la tension de dépression.4. Amplifier according to the preceding claim, characterized in that it comprises means for controlling the voltage source (30) located between the common point (32) and the cathode (16) in order to keep the voltage source constant (30) in the event of a reduction in the vacuum voltage.
5. Amplificateur selon l'une des revendications précédentes, caractérisé en ce que le tube est destiné à fonctionner en bande UHF ou L ou S ou C ou X ou Ku ou K ou Ka.5. Amplifier according to one of the preceding claims, characterized in that the tube is intended to operate in UHF or L or S or C or X or Ku or K or Ka band.
6. Amplificateur selon l'une des revendications précédentes, caractérisé en ce que le tube est un tube à sortie inductive, ou un tube à ondes progressives ou un klystron. 6. Amplifier according to one of the preceding claims, characterized in that the tube is an inductive output tube, or a traveling wave tube or a klystron.
7. Emetteur comportant un amplificateur selon l'une des revendications précédentes. 7. Transmitter comprising an amplifier according to one of the preceding claims.
EP04766881A 2003-10-10 2004-10-08 Amplifier comprising an electronic tube provided with collectors Withdrawn EP1671345A2 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR0311904A FR2860916B1 (en) 2003-10-10 2003-10-10 AMPLIFIER WITH ELECTRONIC COLLECTOR TUBE
PCT/EP2004/052484 WO2005038848A2 (en) 2003-10-10 2004-10-08 Amplifier comprising an electronic tube provided with collectors

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EP1671345A2 true EP1671345A2 (en) 2006-06-21

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EP04766881A Withdrawn EP1671345A2 (en) 2003-10-10 2004-10-08 Amplifier comprising an electronic tube provided with collectors

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EP (1) EP1671345A2 (en)
FR (1) FR2860916B1 (en)
WO (1) WO2005038848A2 (en)

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US7368874B2 (en) * 2005-02-18 2008-05-06 Communications and Power Industries, Inc., Satcom Division Dynamic depressed collector
WO2015172352A1 (en) 2014-05-15 2015-11-19 Seagate Technology Llc Storage device tampering detection
US9489542B2 (en) 2014-11-12 2016-11-08 Seagate Technology Llc Split-key arrangement in a multi-device storage enclosure
FR3042307B1 (en) * 2015-10-07 2017-11-03 Thales Sa BALANCING A MULTIFACEUM INDUCTIVE OUTPUT TUBE

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Publication number Priority date Publication date Assignee Title
US3644778A (en) * 1969-10-23 1972-02-22 Gen Electric Reflex depressed collector
SE399987B (en) * 1976-06-23 1978-03-06 Ericsson Telefon Ab L M HIGH VOLTAGE UNIT FOR A PULSE PASSED TRACK
FR2671929A1 (en) * 1991-01-18 1992-07-24 Thomson Tubes Electroniques HEATING GENERATOR BY HIGH FREQUENCY.
JPH07101596B2 (en) * 1992-12-09 1995-11-01 株式会社宇宙通信基礎技術研究所 Traveling wave tube amplifier
US6380803B2 (en) * 1993-09-03 2002-04-30 Litton Systems, Inc. Linear amplifier having discrete resonant circuit elements and providing near-constant efficiency across a wide range of output power

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Title
See references of WO2005038848A2 *

Also Published As

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FR2860916B1 (en) 2006-01-21
WO2005038848A3 (en) 2005-12-01
US20070030058A1 (en) 2007-02-08
WO2005038848A2 (en) 2005-04-28
FR2860916A1 (en) 2005-04-15
US7474148B2 (en) 2009-01-06

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