DE538983C

DE538983C - Method for generating vibrations by means of electron tubes using a falling grid current characteristic

Info

Publication number: DE538983C
Application number: DEL61153D
Authority: DE
Original assignee: Standard Elektrik Lorenz AG; C Lorenz AG
Current assignee: Alcatel Lucent Deutschland AG; C Lorenz AG
Priority date: 1924-09-11
Filing date: 1924-09-11
Publication date: 1931-11-20

Description

Es ist bereits ein Verfahren zur Schwingungserzeugung mittels Drei - Elektroden-Vakuumröhren bekannt geworden, welches darauf beruht, daß dem Gitter eine derartige positive Vorspannung gegeben wird, daß die aus der Glühkathode austretenden und auf dasselbe auftreffenden Elektronen Sekundärelektronen auslösen, was eine fallende Gitterstromcharakteristik zum Gefolge hat. In einem parallel zur Glühkathode und zum Gitter angeschalteten Schwingungskreis können daher Eigenschwingungen konstanter Amplitude aufrechterhalten werden. Der gesamte Mechanismus der Schwingungserzeugung ist dabei auf den Gitterkreis allein beschränkt, und eine sogenannte Rückkopplung mit ihren bekannten Nachteilen fällt fort. Die Dimensionierung des Anodenkreises ist infolgedessen unabhängig von der des Gitterkreises, und es treten im Anodenkreis die im Gitterkreis erzeugten Schwingungen lediglich in verstärkter Form auf. Die Anordnung kann verglichen werden mit der eines fremdgesteuerten Röhrensenders, bei dem der Steuersender der Gitterschwingungskreis ist. Zur Erläuterung sind die beiden Abb. 1 und 2 beigefügt. Abb. 1 zeigt die Gitterstromcharakteristik, deren für die Schwingungserzeugung in Frage kommender Teil mit A-B bezeichnet ist. ig bedeutet dabei den Gitterstrom und ta den Anodenstrom, beide in Abhängigkeit von der Gitterspannung. Abb. 2 zeigt die bekannte Schaltungsanordnung. Die aus Kathode E, Gitter R, Anode A bestehende Röhre enthält einerseits den obenerwähnten, die Frequenz der Schwingungen bedingenden Gitterschwingungskreis, andererseits den diese Schwingungen in verstärktem Maße übertragenden Anodenkreis K, der durch die Kopplungsvorrichtung F mit 40-einer Verbraucheranordnung verbunden zu denken ist. eh ist die Heizspannung für die Glühkathode, ea die Anodenspannung und eg die für das Arbeiten an einem Punkt fallender Gitterstromcharakteristik erforderliehe positive Gittervorspannung.A method for generating vibrations by means of three-electrode vacuum tubes has already become known, which is based on the fact that the grid is given such a positive bias that the electrons emerging from the hot cathode and striking it trigger secondary electrons, which results in a falling grid current characteristic Has. Natural oscillations of constant amplitude can therefore be maintained in an oscillating circuit connected in parallel to the hot cathode and the grid. The entire mechanism of the generation of vibrations is limited to the lattice circle alone, and so-called feedback, with its known disadvantages, is eliminated. The dimensioning of the anode circle is consequently independent of that of the grid circle, and the vibrations generated in the grid circle only occur in amplified form in the anode circle. The arrangement can be compared to that of an externally controlled tube transmitter, in which the control transmitter is the lattice oscillation circuit. Both figs. 1 and 2 are attached for explanation. Fig. 1 shows the grid current characteristic, the part of which for the generation of vibrations is labeled AB. ig means the grid current and ta the anode current, both depending on the grid voltage. Fig. 2 shows the known circuit arrangement. The tube consisting of cathode E, grid R, anode A contains, on the one hand, the above-mentioned grid oscillation circuit, which determines the frequency of the oscillations, and, on the other hand, the anode circuit K, which transmits these oscillations to an increased extent and which can be thought of as being connected to a consumer arrangement through the coupling device F. eh is the heating voltage for the hot cathode, ea is the anode voltage and eg is the positive grid bias voltage required for working at a point where the grid current characteristic is falling.

Die vorliegende Erfindung hat nun zum Gegenstand eine Weiterentwicklung dieses \^rerfahrens, die sich für eine praktisch wirtschaftliche Schwingungserzeugung als nötig erweist. Damit nämlich eine ausreichende Verstärkung der im Gitterkreis erzeugten Schwingungen durch den Anodenkreis eintritt, ist es erfindungsgemäß nötig, daß der Anodenstrom innerhalb des Bereiches fallender Gitterstromcharakteristik, d. h. positiver Gittervorspannung, noch in seinem möglichst am stärksten ansteigenden Teil verläuft, so daß schon die geringsten im Gitterkreis erregten Eigenschwingungen den Anodenkreis ins Schwingen geraten lassen (s. Bereich yi-S, Abb. 1). Da nun, wie schon erwähnt, für das Arbeiten der Röhre eine bestimmte positive Vorspannung nötig ist, so werden nicht ohne weiteres bei jeder Röhre diese Bedingungen vorhanden sein. Die üblichen Mittel nun, dasThe present invention now has the object of this \ ^r experiencing that proves an evolution for a practical economic vibrator than necessary. In order for the oscillations generated in the grid circle to be sufficiently amplified by the anode circle, it is necessary according to the invention that the anode current within the range of falling grid current characteristics, i.e. positive grid bias, still runs in its most steeply rising part, so that even the slightest in the grid circle excited natural oscillations cause the anode circle to start oscillating (see area yi-S, Fig. 1). Since, as already mentioned, a certain positive bias voltage is necessary for the operation of the tube, these conditions will not necessarily be present in every tube. The usual means well, that

Claims

Increase in the anode current or the anode current characteristic in the area Postponing higher grid voltages is known to be small penetration, i. H. a close-meshed grid and, secondly, a large distance between the grid and the cathode, because by the latter, the grid voltages required to achieve saturation are greater Need to become. Another means consists in inserting one or more predominantly negatively charged grid. As the once-fanned lattice vibrations with little damping of the lattice circle too The anode current can go beyond the area of the falling grid current characteristic can still be fully controlled even if the area of its rise is partially lies outside the area of falling grid current characteristic.

Further investigation of these processes showed that one could see the onset of a falling Lattice current characteristic and in particular the strength of the drop are significant as a result can influence the lattice with an easily electron donating substance (electropositive substances), such as oxides, salts of alkali metals or alkaline Earth, Thor, Uranium, or other heavy atomic or radioactive substances in elementary State or in links, provides. The electrons hitting the grid This is because it is particularly easy to trigger secondary electrons if there are substances on them that release electrons are particularly suitable. But even if only the cathode is provided with these substances is to be in the course of the operation of the tube

partly by the ejected electrons, partly by evaporation or similar processes Sufficiently large amounts of these substances are transferred to the grid electrode, which causes the occurrence of secondary electrons can favor.

Sponsors tansi ^j r ü chk:

i. Process for generating vibrations by means of electron tubes with utilization a falling grid current characteristic, characterized by the use of tubes in which the Area of decreasing grid current characteristic with the area of increasing anode current characteristic coincides, on the one hand, by the falling grid current characteristic even at low positive grid voltages begins, on the other hand, the increase in the anode current characteristics in the area of high grid voltages extends.

2. The method according to claim 1, characterized in that a tube with small penetration is used.

3. The method according to claim 1 and 2, characterized in that the distance of the grid from the cathode enlarged

• will.

4. The method according to claim 1 to 3, characterized in that one or several predominantly negatively charged auxiliary grids can be used.

5. The method according to claim 1 to 4, characterized in that the grid is provided with an easily electron donating (electropositive) substance.

1 sheet of drawings