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EP0496008B1 - Controllable high-power electron tube - Google Patents

Controllable high-power electron tube Download PDF

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Publication number
EP0496008B1
EP0496008B1 EP91100661A EP91100661A EP0496008B1 EP 0496008 B1 EP0496008 B1 EP 0496008B1 EP 91100661 A EP91100661 A EP 91100661A EP 91100661 A EP91100661 A EP 91100661A EP 0496008 B1 EP0496008 B1 EP 0496008B1
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EP
European Patent Office
Prior art keywords
cathode
electron tube
control grid
anode
power electron
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.)
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EP91100661A
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German (de)
French (fr)
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EP0496008A1 (en
Inventor
Fritz Dr. Lüssi
Hans-Günter Dr. Mathews
Werner Dr. Rohrbach
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THOMSON ELEKTRONENROEHREN AG
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Thomson Elektronenrohren AG
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Priority to EP91100661A priority Critical patent/EP0496008B1/en
Priority to DE59106482T priority patent/DE59106482D1/en
Priority to US07/805,613 priority patent/US5206565A/en
Publication of EP0496008A1 publication Critical patent/EP0496008A1/en
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Publication of EP0496008B1 publication Critical patent/EP0496008B1/en
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J21/00—Vacuum tubes
    • H01J21/02—Tubes with a single discharge path
    • H01J21/06—Tubes with a single discharge path having electrostatic control means only
    • H01J21/10—Tubes with a single discharge path having electrostatic control means only with one or more immovable internal control electrodes, e.g. triode, pentode, octode
    • H01J21/14—Tubes with means for concentrating the electron stream, e.g. beam tetrode
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J19/00—Details of vacuum tubes of the types covered by group H01J21/00
    • H01J19/02—Electron-emitting electrodes; Cathodes
    • H01J19/04—Thermionic cathodes
    • H01J19/14—Cathodes heated indirectly by an electric current; Cathodes heated by electron or ion bombardment
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J19/00—Details of vacuum tubes of the types covered by group H01J21/00
    • H01J19/42—Mounting, supporting, spacing, or insulating of electrodes or of electrode assemblies

Definitions

  • the present invention relates to the field of power electronics. It relates in particular to a controllable high-performance electron tube in the form of a tetrode with an output power P0 of at least 100 kW, which high-performance electron tube in a coaxial, cylindrical arrangement comprises a cathode, a control grid, a screen grid and an anode.
  • Such a high-performance electron tube is e.g. under the type designation CQK 50-2 from Brown Boveri Mitt. 66, 1979 (1), pp. 40-42.
  • CQK 50-2 from Brown Boveri Mitt. 66, 1979 (1), pp. 40-42.
  • the typical application of this tube in a radio transmitter is described in Brown Boveri Mitt. 67, 1980 (3), pp. 215-219.
  • High-performance electron tubes of the type mentioned at the outset are usually used as output stage tubes in radio transmitters with amplitude modulation (AM), in particular in the shortwave range (approximately 3.9-26.1 MHz).
  • AM amplitude modulation
  • Such a radio transmitter comprises an LF and an HF part.
  • the LF part ensures the conditioning and power amplification of the LF signal to be transmitted, which is then (in the usual anode modulation) applied to the anode of the power amp tube.
  • the carrier frequency oscillator with the following driver stage provides a power-amplified carrier signal in the HF section, which reaches the control grid of the power amplifier tube and, together with the anode voltage oscillating in time with the LF signal, outputs the desired AM signal to a load, the antenna .
  • radio transmitters usually operate in a power range from more than 50 kW to a few 100 kW output power, the efficiency, i.e. the ratio of used to usable performance, a central role.
  • the output tube has a significant share in the overall efficiency of the transmitter, which can be greater than 70%.
  • anode efficiency is, among other things, proportional to the expression 1- (u s / u a0 ), where u s (also called U ar ) denotes the residual voltage which cannot be driven and u a0 (also called U a ) the anode DC voltage.
  • the anode efficiency therefore increases with constant residual voltage with increasing anode direct voltage (Brown Boveri Mitt. 71, 1984 (5), p.199).
  • a good anode efficiency therefore requires a high anode DC voltage u a0 in all cases so that the non-modifiable rest u s remains relatively small (see: Meinke / Gundlach, Taschenbuch der Hochfrequenztechnik, 3rd edition, Springer-Verlag 1968, p.1035- 1037).
  • the usual operating voltages for large transmitters with high-performance tetrodes in the HF output stage are therefore today between 10 and 14 kV (see: Meinke / Gundlach, Taschenbuch der Hochfrequenztechnik, 4th edition, Springer-Verlag 1986, S.P9).
  • the comparatively high anode voltages in connection with the anode modulation require appropriately designed modulation amplifiers, which have to deliver output voltages of 0 to 28 kV at an anode DC voltage of 14 kV.
  • PSM pulse level modulator
  • 32 switching stages are required within this PSM, for example, the output voltages of which add up to the desired anode voltage (Brown Boveri Tech. 74, 1987 (6), pp. 296-302). Since each of these 32 high-performance switching stages takes up space, separate cabinets must be provided for the PSM in the transmitter.
  • the transmitter circuit But also with other components of the transmitter circuit, the high anode DC voltage and the necessary dielectric strength lead to increased space requirements, so that the transmitter as a whole has to be designed in a very complex manner.
  • the object is achieved in a high-performance electron tube as defined in claim 1.
  • the essence of the invention is to design the tube as a "low voltage" or low voltage tetrode, which has a comparable efficiency as conventional high-performance tetrodes with a significantly reduced anode DC voltage.
  • the reduction of the anode DC voltage with constant efficiency is achieved in the high-performance electron tube according to claim 1 by a considerable reduction in the electrode spacing, which is possible, among other things, that the cathode temperature is drastically reduced by a special structure of the cathode with high electron emission.
  • the efficiency of the tube and thus of the transmitter can be largely maintained.
  • FIG. 1 A preferred embodiment of a "low voltage" tetrode according to the invention, which is operated at an anode efficiency of greater than 80% (in particular> 83%) with an anode DC voltage of less than 10 kV (in particular approximately 5 kV), and which is used as an output stage tube for a 100 kW short-wave transmitter is provided, is shown in Fig. 1 in section. For reasons of clarity, a detailed representation of the lower tube foot and the external anode cooling (which are known per se) has been omitted.
  • the electrode arrangement of the tube is shown in detail and enlarged in FIG. 2.
  • the tube shown contains as essential elements in a coaxial arrangement from the inside out, a cylindrical, full-walled matrix cathode 10, a cup-shaped control grid 8, a cup-shaped screen grid 7 and an anode cylinder 3, which is closed at the top by an anode cover 2.
  • the anode cylinder 3 is insulated from the tube base by a ceramic ring 14.
  • the screen grid 7 merges downwards into a screen grid connection 15, the control grid 8 into a control grid connection 18, and the matrix cathode 10 into a cathode connection 17.
  • the matrix cathode 10 contains BaO in a metal matrix, which forms a Ba layer on the surface, which emits compared to conventional tungsten-thorium cathodes (working temperature: approximately 1900 ° K) at much lower temperatures (approximately 1000-1100 ° K).
  • the matrix cathode 10 is indirectly heated by a heating coil 12 arranged on its inside and shielded inwards by a radiation shield 19. The heating current required for this is supplied to the heating coil 12 via a central inner sheet metal cylinder 13 and an adjoining supply line 11 and via the cathode connection 17.
  • the winding density of the heating coil 12 preferably varies in the axial direction: the coil is in each case wound more tightly at the ends of the cathode cylinder than in the middle. This measure allows a uniform temperature distribution to be set in accordance with the tube design, which is necessary to ensure homogeneous emission over the entire cathode surface.
  • the comparatively low working temperature of the matrix cathode 10 reduces, in addition to the required heating power, above all the thermo-mechanical tension in the electrode system caused by temperature differences so that control grid 8 and screen grid 7 can be arranged very close to the cathode.
  • the distance between the cathode and the control grid and the distance between the control grid and the screen grid are between 1 and 2 mm in the case of a conventional high-power transmission tetrode with tungsten-thorium cathode and an anode DC voltage of approximately 14 kV, these distances are (a1 and a2 in FIG. 2) in the exemplary embodiment described here is less than 1 mm and is preferably approximately 0.55 mm or 0.45 mm for a “low voltage” tetrode with an anode direct voltage of approximately 5 kV.
  • control grids 8 and screen grids 7 are attached at their upper end via ceramic disks 5, 6 and a central ceramic sleeve 4 to a holding plate 9 starting from the matrix cathode 10 .
  • the control grid connection 18 is guided through the cathode connection 17 into the interior and is supported there, preferably by means of a first ceramic support ring 20, on the cathode connection 17.
  • Control grille 8 and screen grille 7 are preferably made in the form of openwork cylinders made of pyrolytic graphite and each have a thickness (d1 or d2 in FIG. 2) of approximately 0.3 mm. The distance between that Screen grid 7 and the anode cylinder 3 (a3 in FIG. 2) is then about 6.4 mm.
  • the high-performance electron tube according to the invention enables the construction of a transmitter, which is characterized by a compact structure and a very high level of reliability with an unchanged high overall efficiency.

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Description

TECHNISCHES GEBIETTECHNICAL AREA

Die vorliegende Erfindung bezieht sich auf das Gebiet der Leistungselektronik. Sie betrifft insbesondere eine steuerbare Hochleistungs-Elektronenröhre in Form einer Tetrode mit einer Ausgangsleistung P₀ von wenigstens 100 kW, welche Hochleistungs-Elektronenröhre in koaxialer, zylindrischer Anordnung eine Kathode, ein Steuergitter, ein Schirmgitter und eine Anode umfasst.The present invention relates to the field of power electronics. It relates in particular to a controllable high-performance electron tube in the form of a tetrode with an output power P₀ of at least 100 kW, which high-performance electron tube in a coaxial, cylindrical arrangement comprises a cathode, a control grid, a screen grid and an anode.

Eine solche Hochleistungs-Elektronenröhre ist z.B. unter der Typenbezeichnung CQK 50-2 aus der Druckschrift Brown Boveri Mitt. 66, 1979(1), S.40-42, bekannt. Die typische Anwendung dieser Röhre in einem Rundfunksender ist in der Druckschrift Brown Boveri Mitt. 67, 1980(3), S.215-219, beschrieben.Such a high-performance electron tube is e.g. under the type designation CQK 50-2 from Brown Boveri Mitt. 66, 1979 (1), pp. 40-42. The typical application of this tube in a radio transmitter is described in Brown Boveri Mitt. 67, 1980 (3), pp. 215-219.

STAND DER TECHNIKSTATE OF THE ART

Hochleistungs-Elektronenröhren der eingangs genannten Art werden üblicherweise als Endstufenröhren in Rundfunksendern mit Amplitudenmodulation (AM), insbesondere im Kurzwellenbereich (etwa 3,9 - 26,1 MHz), eingesetzt. Ein solcher Rundfunksender umfasst dabei einen NF- und einen HF-Teil.High-performance electron tubes of the type mentioned at the outset are usually used as output stage tubes in radio transmitters with amplitude modulation (AM), in particular in the shortwave range (approximately 3.9-26.1 MHz). Such a radio transmitter comprises an LF and an HF part.

Der NF-Teil sorgt für die Aufbereitung und Leistungsverstärkung des zu übertragenden NF-Signals, welches dann (bei der üblichen Anodenmodulation) auf die Anode der Endstufenröhre gegeben wird. Der Trägerfrequenz-Oszillator mit der nachfolgenden Treiberstufe stellt im HF-Teil ein leistungsverstärktes Trägersignal bereit, welches auf das Steuergitter der Endstufenröhre gelangt und zusammen mit der im Takt des NF-Signals schwingenden Anodenspannung das gewünschte AM-Signal an eine Last, die Antenne, abgibt.The LF part ensures the conditioning and power amplification of the LF signal to be transmitted, which is then (in the usual anode modulation) applied to the anode of the power amp tube. The carrier frequency oscillator with the following driver stage provides a power-amplified carrier signal in the HF section, which reaches the control grid of the power amplifier tube and, together with the anode voltage oscillating in time with the LF signal, outputs the desired AM signal to a load, the antenna .

Da derartige Rundfunksender üblicherweise in einem Leistungsbereich von mehr als 50 kW bis zu einigen 100 kW Ausgangsleistung arbeiten, spielt bei der Entwicklung und Auslegung eines solchen Senders der Wirkungsgrad, d.h. das Verhältnis von eingesetzter zu nutzbarer Leistung, eine zentrale Rolle. Massgeblichen Anteil am Gesamtwirkungsgrad des Senders, der grösser 70% sein kann, hat dabei die Endstufenröhre.Since such radio transmitters usually operate in a power range from more than 50 kW to a few 100 kW output power, the efficiency, i.e. the ratio of used to usable performance, a central role. The output tube has a significant share in the overall efficiency of the transmitter, which can be greater than 70%.

Ihr Wirkungsgrad, der sogenannte Anodenwirkungsgrad ist unter anderem proportional zu dem Ausdruck 1-(us/ua0), wobei us (auch Uar genannt) die nicht aussteuerbare Restspannung und ua0 (auch Ua genannt) die Anodengleichspannung bezeichnet. Der Anodenwirkungsgrad steigt daher bei konstanter Restspannung mit zunehmender Anodengleichspannung (Brown Boveri Mitt. 71, 1984(5), S.199).Their efficiency, the so-called anode efficiency, is, among other things, proportional to the expression 1- (u s / u a0 ), where u s (also called U ar ) denotes the residual voltage which cannot be driven and u a0 (also called U a ) the anode DC voltage. The anode efficiency therefore increases with constant residual voltage with increasing anode direct voltage (Brown Boveri Mitt. 71, 1984 (5), p.199).

Ein guter Anodenwirkungsgrad fordert deshalb in allen Fällen eine hohe Anodengleichspannung ua0, damit der nicht aussteuerbare Rest us demgegenüber relativ klein bleibt (siehe dazu: Meinke/Gundlach, Taschenbuch der Hochfrequenztechnik, 3.Auflage, Springer-Verlag 1968, S.1035-1037). Die üblichen Betriebsspannungen bei Grosssendern mit Hochleistungs-Tetroden in der HF-Endstufe liegen daher heute zwischen 10 und 14 kV (siehe dazu: Meinke/Gundlach, Taschenbuch der Hochfrequenztechnik, 4.Auflage, Springer-Verlag 1986, S.P9).A good anode efficiency therefore requires a high anode DC voltage u a0 in all cases so that the non-modifiable rest u s remains relatively small (see: Meinke / Gundlach, Taschenbuch der Hochfrequenztechnik, 3rd edition, Springer-Verlag 1968, p.1035- 1037). The usual operating voltages for large transmitters with high-performance tetrodes in the HF output stage are therefore today between 10 and 14 kV (see: Meinke / Gundlach, Taschenbuch der Hochfrequenztechnik, 4th edition, Springer-Verlag 1986, S.P9).

Als Beispiele für diese im Stand der Technik erreichten Werte sei auf die folgenden beiden Kurzwellensender hingewiesen:

  • (1) Auf den in der Druckschrift Brown Boveri Mitt. 69, 1982(6), S.212-217, beschriebenen 250-kW-Kurzwellensender, der in seiner HF-Endstufe mit einer Hochleistungs-Tetrode vom Typ BBC CQK 350-1 bestückt ist. Diese Tetrode arbeitet bei Anodenmodulation im Klasse-C-Betrieb mit einer Anodengleichspannung von 14 kV, einer Schirmgittergleichspannung von 1300 V und einer Steuergittergleichspannung von -900 V und hat einen Wirkungsgrad von 85,2%.
  • (2) Auf den in der eingangs genannten Druckschrift Brown Boveri Mitt. 67, 1980(3), S.215-219 beschriebenen 100-kW-Kurzwellensender, der in seiner HF-Endstufe mit einer Hochleistungs-Tetrode vom Typ BBC CQK 50-2 bestückt ist. Diese Tetrode arbeitet bei Anodenmodulation im Klasse-C-Betrieb mit einer Anodengleichspannung von 11 kV, einer Schirmgittergleichspannung von 800 V und einer Steuergittergleichspannung von -600 V (siehe auch: BBC Kurzdatenkatalog Elektronenröhren, Druckschrift-Nr. CH-E 3.30475.8 D/F/E/S von 1982/83).
The following two shortwave transmitters are mentioned as examples of these values achieved in the prior art:
  • (1) On the 250 kW short-wave transmitter described in the publication Brown Boveri Mitt. 69, 1982 (6), pp. 212-217, which in its HF output stage has a high-performance tetrode of the type BBC CQK 350-1 is equipped. With anode modulation in class C operation, this tetrode works with an anode DC voltage of 14 kV, a screen grid DC voltage of 1300 V and a control grid DC voltage of -900 V and has an efficiency of 85.2%.
  • (2) On the 100 kW short-wave transmitter described in the aforementioned Brown Boveri Mitt. 67, 1980 (3), pp. 215-219, which uses a high-performance tetrode of the BBC CQK 50- 2 is equipped. With anode modulation in class C operation, this tetrode works with an anode DC voltage of 11 kV, a screen grid DC voltage of 800 V and a control grid DC voltage of -600 V (see also: BBC Brief Data Catalog for Electron Tubes, publication no. CH-E 3.30475.8 D / F / E / S from 1982/83).

Die vergleichsweise hohen Anodenspannungen erfordern im Zusammenhang mit der Anodenmodulation entsprechend ausgelegte Modulationsverstärker, die bei einer Anodengleichspannung von 14 kV Ausgangsspannungen von 0 bis 28 kV liefern müssen.The comparatively high anode voltages in connection with the anode modulation require appropriately designed modulation amplifiers, which have to deliver output voltages of 0 to 28 kV at an anode DC voltage of 14 kV.

Wird als Modulationsverstärker z.B. ein Pulsstufenmodulator PSM, d.h. ein digitaler Schaltverstärker, verwendet, werden innerhalb dieses PSM beispielsweise 32 Schaltstufen benötigt, deren Ausgangsspannungen sich zu der gewünschten Anodenspannung addieren (Brown Boveri Tech. 74, 1987(6), S.296-302). Da jede einzelne dieser 32 Hochleistungs-Schaltstufen entsprechenden Raum beansprucht, müssen für den PSM im Sender separate Schränke vorgesehen werden.Is used as a modulation amplifier e.g. a pulse level modulator PSM, i.e. a digital switching amplifier, 32 switching stages are required within this PSM, for example, the output voltages of which add up to the desired anode voltage (Brown Boveri Tech. 74, 1987 (6), pp. 296-302). Since each of these 32 high-performance switching stages takes up space, separate cabinets must be provided for the PSM in the transmitter.

Aber auch bei anderen Komponenten der Senderschaltung führt die hohe Anodengleichspannung und die dafür notwendige Spannungsfestigkeit zu erhöhtem Platzbedarf, sodass der Sender insgesamt sehr aufwendig ausgestaltet sein muss.But also with other components of the transmitter circuit, the high anode DC voltage and the necessary dielectric strength lead to increased space requirements, so that the transmitter as a whole has to be designed in a very complex manner.

DARSTELLUNG DER ERFINDUNGPRESENTATION OF THE INVENTION

Aufgabe der vorliegenden Erfindung ist es daher, eine Hochleistungs-Elektronenröhre zu schaffen, mit der ein Rundfunksender aufgebaut werden kann, welcher sich bei gleichbleibendem Wirkungsgrad durch einen verminderten konstruktiven Aufwand sowie geringeren Platzbedarf auszeichnet.It is therefore an object of the present invention to provide a high-performance electron tube with which a radio transmitter can be constructed, which is characterized by a reduced design effort and a smaller space requirement while maintaining efficiency.

Die Aufgabe wird bei einer Hochleistungs-Elektronenröhre, wie im Anspruch 1 definiert, gelöst.The object is achieved in a high-performance electron tube as defined in claim 1.

Der Kern der Erfindung besteht darin, die Röhre als eine "Low Voltage"- oder Niederspannungs-Tetrode auszubilden, welche bei einer deutlich verringerten Anodengleichspannung einen vergleichbaren Wirkungsgrad wie herkömmliche Hochleistungs-Tetroden aufweist.The essence of the invention is to design the tube as a "low voltage" or low voltage tetrode, which has a comparable efficiency as conventional high-performance tetrodes with a significantly reduced anode DC voltage.

Die Reduktion der Anodengleichspannung bei gleichbleibendem Wirkungsgrad wird bei der Hochleistungs-Elektronenröhre gemäß Anspruch 1 erreicht durch eine erhebliche Verringerung der Elektrodenabstände, die unter anderem dadurch möglich wird, dass durch einen speziellen Aufbau der Kathode bei hoher Elektronenemission die Kathodentemperatur drastisch reduziert ist.The reduction of the anode DC voltage with constant efficiency is achieved in the high-performance electron tube according to claim 1 by a considerable reduction in the electrode spacing, which is possible, among other things, that the cathode temperature is drastically reduced by a special structure of the cathode with high electron emission.

Da mit der Anodengleichspannung auch die Gittergleichspannungen verringert werden (die Steuergittergleichspannung bestimmt die oben erwähnte Anodenrestspannung), kann der Wirkungsgrad der Röhre und damit des Senders weitgehend qehalten werden.Since the DC anode voltage also reduces the DC grid voltages (the control grid DC voltage determines the above-mentioned residual anode voltage), the efficiency of the tube and thus of the transmitter can be largely maintained.

Weitere Ausführungsformen ergeben sich aus den abhängigen Ansprüchen.Further embodiments result from the dependent claims.

KURZE BESCHREIBUNG DER ZEICHNUNGBRIEF DESCRIPTION OF THE DRAWING

Die Erfindung soll nachfolgend anhand von Ausführungsbeispielen im Zusammenhang mit der Zeichnung näher erläutert werden. Es zeigen

Fig. 1
im Querschnitt den Aufbau einer "Low Voltage"-Tetrode gemäss einem bevorzugten Ausführungsbeispiel der Erfindung; und
Fig. 2
im vergrösserten Ausschnitt die Geometrie der Elektrodenanordnung in einer Röhre gemäss Fig. 1.
The invention will be explained in more detail below on the basis of exemplary embodiments in connection with the drawing. Show it
Fig. 1
in cross section the structure of a "low voltage" tetrode according to a preferred embodiment of the invention; and
Fig. 2
in an enlarged detail the geometry of the electrode arrangement in a tube according to FIG. 1.

WEGE ZUR AUSFÜHRUNG DER ERFINDUNGWAYS OF CARRYING OUT THE INVENTION

Eine bevorzugte Ausführungsform einer "Low Voltage"-Tetrode nach der Erfindung, die bei einem Anodenwirkungsgrad von grösser 80% (insbesondere >83%) mit einer Anodengleichspannung von weniger als 10 kV (insbesondere etwa 5 kV) betrieben wird, und die als Endstufenröhre für einen 100-kW-Kurzwellensender vorgesehen ist, ist in Fig. 1 im Schnitt wiedergegeben. Aus Gründen der Uebersichtlichkeit ist dabei auf eine detaillierte Darstellung des unteren Röhrenfusses sowie der äusseren Anodenkühlung (die an sich bekannt sind) verzichtet worden.A preferred embodiment of a "low voltage" tetrode according to the invention, which is operated at an anode efficiency of greater than 80% (in particular> 83%) with an anode DC voltage of less than 10 kV (in particular approximately 5 kV), and which is used as an output stage tube for a 100 kW short-wave transmitter is provided, is shown in Fig. 1 in section. For reasons of clarity, a detailed representation of the lower tube foot and the external anode cooling (which are known per se) has been omitted.

Die Elektrodenanordnung der Röhre ist ausschnittweise und vergrössert in Fig. 2 dargestellt.The electrode arrangement of the tube is shown in detail and enlarged in FIG. 2.

Die gezeigte Röhre enthält als wesentliche Elemente in koaxialer Anordnung von innen nach aussen eine zylindrische, vollwandige Matrixkathode 10, ein topfförmiges Steuergitter 8, ein topfförmiges Schirmgitter 7 sowie einen Anodenzylinder 3, der oben durch einen Anodendeckel 2 verschlossen ist.The tube shown contains as essential elements in a coaxial arrangement from the inside out, a cylindrical, full-walled matrix cathode 10, a cup-shaped control grid 8, a cup-shaped screen grid 7 and an anode cylinder 3, which is closed at the top by an anode cover 2.

Der Anodenzylinder 3 ist zum Röhrenfuss hin durch einen Keramikring 14 isoliert. Das Schirmgitter 7 geht nach unten hin in einen Schirmgitter-Anschluss 15, das Steuergitter 8 in einen Steuergitter-Anschluss 18, und die Matrixkathode 10 in einen Kathoden-Anschluss 17 über.The anode cylinder 3 is insulated from the tube base by a ceramic ring 14. The screen grid 7 merges downwards into a screen grid connection 15, the control grid 8 into a control grid connection 18, and the matrix cathode 10 into a cathode connection 17.

Die Matrixkathode 10 enthält in einer Metallmatrix BaO, welches auf der Oberfläche eine Ba-Schicht bildet, die gegenüber herkömmlichen Wolfram-Thorium-Kathoden (Arbeitstemperatur: etwa 1900°K) bei sehr viel niedrigeren Temperaturen (etwa 1000-1100°K) emittiert. Die Matrixkathode 10 wird durch eine auf ihrer Innenseite angeordnete, nach innen durch ein Strahlungsschild 19 abgeschirmte Heizwendel 12 indirekt beheizt. Der dazu benötigte Heizstrom wird der Heizwendel 12 über einen zentralen inneren Blechzylinder 13 und eine daran anschliessende Zuleitung 11 sowie über den Kathoden-Anschluss 17 zugeführt.The matrix cathode 10 contains BaO in a metal matrix, which forms a Ba layer on the surface, which emits compared to conventional tungsten-thorium cathodes (working temperature: approximately 1900 ° K) at much lower temperatures (approximately 1000-1100 ° K). The matrix cathode 10 is indirectly heated by a heating coil 12 arranged on its inside and shielded inwards by a radiation shield 19. The heating current required for this is supplied to the heating coil 12 via a central inner sheet metal cylinder 13 and an adjoining supply line 11 and via the cathode connection 17.

Wie aus Fig. 1 ersichtlich, variiert vorzugsweise die Windungsdichte der Heizwendel 12 in axialer Richtung: die Wendel ist jeweils an den Enden des Kathodenzylinders enger gewickelt, als in der Mitte. Durch diese Massnahme kann entsprechend der Röhrenausführung eine gleichmässige Temperaturverteilung eingestellt werden, was nötig ist, um eine homogene Emission über die ganze Kathodenoberfläche zu gewährleisten.As can be seen from FIG. 1, the winding density of the heating coil 12 preferably varies in the axial direction: the coil is in each case wound more tightly at the ends of the cathode cylinder than in the middle. This measure allows a uniform temperature distribution to be set in accordance with the tube design, which is necessary to ensure homogeneous emission over the entire cathode surface.

Die vergleichsweise niedrige Arbeitstemperatur der Matrixkathode 10 reduziert neben der erforderlichen Heizleistung vor allem die durch Temperaturunterschiede hervorgerufenen thermo-mechanischen Verspannungen im Elektrodensystem, sodass Steuergitter 8 und Schirmgitter 7 sehr nahe an der Kathode angeordnet werden können.The comparatively low working temperature of the matrix cathode 10 reduces, in addition to the required heating power, above all the thermo-mechanical tension in the electrode system caused by temperature differences so that control grid 8 and screen grid 7 can be arranged very close to the cathode.

Während bei einer herkömmlichen Hochleistungs-Sendetetrode mit Wolfram-Thorium-Kathode und einer Anodengleichspannung von etwa 14 kV der Abstand zwischen der Kathode und dem Steuergitter und der Abstand zwischen dem Steuergitter und dem Schirmgitter zwischen 1 und 2 mm betragen, sind diese Abstände (a1 und a2 in Fig. 2) beim hier beschriebenen Ausführungsbeispiel kleiner 1 mm und betragen vorzugsweise etwa 0,55 mm bzw. 0,45 mm für eine "Low Voltage"-Tetrode mit einer Anodengleichspannung von etwa 5 kV.While the distance between the cathode and the control grid and the distance between the control grid and the screen grid are between 1 and 2 mm in the case of a conventional high-power transmission tetrode with tungsten-thorium cathode and an anode DC voltage of approximately 14 kV, these distances are (a1 and a2 in FIG. 2) in the exemplary embodiment described here is less than 1 mm and is preferably approximately 0.55 mm or 0.45 mm for a “low voltage” tetrode with an anode direct voltage of approximately 5 kV.

Die kleinen Elektrodenabstände mit Toleranzen im Bereich von 1/100 mm erfordern eine sorgfältige Befestigung der einzelnen Elektroden: Steuergitter 8 und Schirmgitter 7 sind an ihrem oberen Ende über Keramikscheiben 5,6 und eine zentrale Keramikhülse 4 an einem von der Matrixkathode 10 ausgehenden Halteblech 9 befestigt. Im Röhrenfuss wird der Steuergitter-Anschluss 18 durch den Kathoden-Anschluss 17 hindurch ins Innere geführt und dort, vorzugsweise mittels eines ersten keramischen Abstützringes 20, am Kathoden-Anschluss 17 abgestützt.The small electrode spacings with tolerances in the range of 1/100 mm require careful attachment of the individual electrodes: control grids 8 and screen grids 7 are attached at their upper end via ceramic disks 5, 6 and a central ceramic sleeve 4 to a holding plate 9 starting from the matrix cathode 10 . In the tube foot, the control grid connection 18 is guided through the cathode connection 17 into the interior and is supported there, preferably by means of a first ceramic support ring 20, on the cathode connection 17.

Durch diese Massnahmen können die kritischen Elektrodenabstände besonders wirkungsvoll eingehalten werden. Weitere Abstützringe, von denen einer (16) in Fig. 1 teilweise dargestellt ist, sind in an sich bekannter Weise zwischen den anderen Anschlüssen angeordnet.These measures allow the critical electrode spacing to be kept particularly effectively. Further support rings, one of which (16) is partially shown in FIG. 1, are arranged between the other connections in a manner known per se.

Steuergitter 8 und Schirmgitter 7 werden bevorzugt in Form durchbrochener Zylinder aus pyrolytischem Graphit gefertigt und jeweils mit einer Dicke (d1 bzw. d2 in Fig. 2) von etwa 0,3 mm hergestellt. Der Abstand zwischen dem Schirmgitter 7 und dem Anodenzylinder 3 (a3 in Fig. 2) beträgt dann etwa 6,4 mm.Control grille 8 and screen grille 7 are preferably made in the form of openwork cylinders made of pyrolytic graphite and each have a thickness (d1 or d2 in FIG. 2) of approximately 0.3 mm. The distance between that Screen grid 7 and the anode cylinder 3 (a3 in FIG. 2) is then about 6.4 mm.

Zur besseren Uebersicht sollen nachfolgend in einer Tabelle die elektrischen Betriebswerte einer "Low Voltage"-Tetrode (LVT) in der bevorzugten Ausführungsform für einen 100-kW-Kurzwellensender noch einmal den Betriebswerten einer herkömmlichen Tetrode gleicher Leistung (der eingangs erwähnten BBC CQK 50-2) gegenübergestellt werden:

Figure imgb0001
For a better overview, the electrical operating values of a "low voltage" tetrode (LVT) in the preferred embodiment for a 100 kW short-wave transmitter are again shown in a table below the operating values of a conventional tetrode of the same power (the BBC CQK 50-2 mentioned at the outset ) are compared:
Figure imgb0001

Aus der Tabelle lässt sich ohne weiteres erkennen, dass die "Low Voltage"-Tetrode gegenüber der herkömmlichen Tetrode bei nahezu unverändertem Wirkungsgrad für ihren Betrieb eine sehr viel kleinere Anodengleichspannung, eine erheblich geringere Ansteuerleistung und eine stark reduzierte Heizleistung erfordert.From the table it can easily be seen that the "low voltage" tetrode requires a much lower anode DC voltage, a considerably lower drive power and a greatly reduced heating power for its operation compared to the conventional tetrode with almost unchanged efficiency.

Diese Eigenschaften haben unmittelbare vorteilhafte Auswirkungen auf die konstruktive Auslegung eines mit dieser Röhre ausgerüsteten Senders:

  • Wegen der niedrigen Anodengleichspannung kann der Modulationsverstärker, wenn er als digitaler PSM-Verstärker ausgebildet ist, statt wie bisher mit 32 nun nur noch mit 14 oder weniger Schaltstufen ausgerüstet sein. Dadurch reduziert sich der Platzbedarf in einem solchen Umfang, dass der PSM-Verstärker direkt im Schrank für den HF-Teil untergebracht werden kann.
  • Wegen der niedrigen Ansteuerleistung kann die vorher übliche Treiberröhre durch einen transistorisierten Treiberverstärker geringerer Leistung ersetzt werden, was dem Gesamtwirkungsgrad zugute kommt und den Platzbedarf weiter verringert.
  • Wegen der reduzierten Heizleistung und der niedrigen Kathodentemperatur verbessert sich der Wirkungsgrad und vergrössert sich die Lebensdauer der Endstufenröhre erheblich.
These properties have a direct, beneficial effect on the design of a transmitter equipped with this tube:
  • Because of the low anode DC voltage, the modulation amplifier, if it is designed as a digital PSM amplifier, can instead of 32 as before now only be equipped with 14 or fewer switching stages. This reduces the space requirement to such an extent that the PSM amplifier can be accommodated directly in the cabinet for the HF part.
  • Because of the low drive power, the previously common driver tube can be replaced by a transistorized driver amplifier of lower power, which benefits the overall efficiency and further reduces the space requirement.
  • Due to the reduced heating power and the low cathode temperature, the efficiency improves and the life of the power amp tube is increased considerably.

Insgesamt wird also durch die Hochleistungs-Elektronenröhre nach der Erfindung der Bau eines Senders ermöglicht, welcher sich bei unverändert hohem Gesamtwirkungsgrad durch einen kompakten Aufbau und eine sehr hohe Zuverlässigkeit auszeichnet.Overall, the high-performance electron tube according to the invention enables the construction of a transmitter, which is characterized by a compact structure and a very high level of reliability with an unchanged high overall efficiency.

Claims (5)

  1. Controllable high-power electron tube (1) in the form of a tetrode having an output power Po of at least 100 kW, which high-power electron tube (1) comprises a cathode, a control grid (8), a screen grid (7) and an anode in coaxial cylindrical arrangement, characterized in that
    (a) the cathode is designed as indirectly heated matrix cathode (10) containing BaO;
    (b) the matrix cathode (10) is constructed as a full-walled cylinder; and
    (c) the control grid (8) and the screen grid (7) have a distance (a2, a1) of less than 1 mm from one another and from the matrix cathode (10), so that the electron tube (1) can exhibit an anode efficiency of greater than 80 % with an anode direct voltage of less than 10 kV.
  2. High-power electron tube according to Claim 1, characterized in that
    (a) the anode direct voltage is about 5 kV;
    (b) the distance (a1) from the control grid (8) to the matrix cathode (10) is about 0.55 mm and the distance (a2) from the screen grid (7) to the control grid (8) is about 0.45 mm; and
    (c) the cathode and control grid (8) exhibit at the base of the high-power electron tube (1) a cylindrical cathode connection (17) and control grid connection (18), the control grid connection (18) extending coaxially in the interior of the cathode connection (17) and being supported against the latter.
  3. High-power electron tube according to Claim 2, characterized in that the control grid (8) and the screen grid (7) are constructed as perforated cylinders of pyrolytic graphite.
  4. High-power electron tube according to Claim 2, characterized in that a ceramic support ring (20) is used for supporting the control grid connection (18) against the cathode connection (17).
  5. High-power electron tube according to Claim 1, characterized in that
    (a) a heating filament (12) is attached to the inside of the cathode cylinder for heating the matrix cathode (10); and
    (b) the heating filament (12) exhibits a varying number of turns per unit length in the axial direction for achieving a uniform temperature distribution over the emission area of the matrix cathode (10).
EP91100661A 1991-01-21 1991-01-21 Controllable high-power electron tube Expired - Lifetime EP0496008B1 (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
EP91100661A EP0496008B1 (en) 1991-01-21 1991-01-21 Controllable high-power electron tube
DE59106482T DE59106482D1 (en) 1991-01-21 1991-01-21 Controllable high-performance electron tube.
US07/805,613 US5206565A (en) 1991-01-21 1991-12-12 High-power low-voltage tetrode having a full walled matrix cathode and a control grid spacing of less than 1 mm

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP91100661A EP0496008B1 (en) 1991-01-21 1991-01-21 Controllable high-power electron tube

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EP0496008A1 EP0496008A1 (en) 1992-07-29
EP0496008B1 true EP0496008B1 (en) 1995-09-13

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Family Cites Families (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE902051C (en) * 1944-07-01 1954-01-18 Siemens Ag Indirectly heated cathode
US2951172A (en) * 1958-10-27 1960-08-30 Rca Corp High power, high frequency electron tube
US4076992A (en) * 1976-06-22 1978-02-28 Rca Corporation Vacuum tube grid structures of phosmic bronze having copper and copper alloy conical supports
US4302701A (en) * 1978-07-07 1981-11-24 Siemens Aktiengesellschaft Directly heated cathode for an electron tube with coaxial electrode design
FR2432215A1 (en) * 1978-07-27 1980-02-22 Thomson Csf ELECTRONIC TUBE WITH CYLINDRICAL GRID IN PYROLYTIC GRAPHITE
DE2842553A1 (en) * 1978-09-27 1980-04-10 Licentia Gmbh HIGH VACUUM PIPES AND THEIR USE IN A PULSE LENGTH MODULATED SWITCHABLE SWITCHING AMPLIFIER
US4295077A (en) * 1980-02-14 1981-10-13 Rca Corporation Circumferentially apertured cylindrical grid for electron tube
DE3017429A1 (en) * 1980-05-07 1981-11-12 Licentia Patent-Verwaltungs-Gmbh, 6000 Frankfurt Emission material for impregnating electron tube cathode - with porous sintered matrix, contains aluminium, barium, calcium, strontium and opt. tungsten
DE3625843A1 (en) * 1986-07-30 1988-02-11 Siemens Ag UMBRELLA ELECTRON TUBES, IN PARTICULAR TRANSMITTING TEDRODE, HIGH PERFORMANCE AND HIGH FREQUENCIES
JPS63236239A (en) * 1987-03-10 1988-10-03 シーメンス、アクチエンゲゼルシヤフト Dispenser cathode for discharge tube and its manufacturing method

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DE59106482D1 (en) 1995-10-19
US5206565A (en) 1993-04-27
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