JPS6342812B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a high frequency electron tube.

The high frequency limit of electron tubes for high frequency amplification is limited by the following factors.

(i) The Q of the resonant circuit cannot be high.

(ii) Resonant capacitance is limited by interelectrode capacitance.

(iii) The inductance of the electrode introduction wire cannot be ignored.

(iv) Electronic transit time cannot be ignored.

The object of the present invention is to improve the characteristics of an electron tube, particularly regarding item (iii).

For the purpose of reducing lead-in inductance, it has been proposed to downsize vacuum tubes, and plate tubes are one example of this. This is the introduction “line”
The idea was to solve the problem by introducing a "board".

However, plate tubes cannot carry large currents, so when high frequencies and high power are required, concentric cylindrical electron tubes with concentric cylindrical electrode structures are used instead of plate tubes. .

The present invention makes a new proposal regarding the electrode structure of a concentric cylindrical electron tube, and provides an electron tube that can be used at higher frequencies and has a large lattice loss.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The electron tube of the present invention will be explained below in comparison with an electron tube according to the prior art with reference to the drawings.

FIG. 1 is an axial cross-sectional view of an example of a concentric cylindrical electron tube according to the prior art.

In the electron tube shown in FIG. 1, a concentric cylindrical lattice 3 is disposed within the cylinder of a cylindrical anode 1, and a directly heated cathode 2 is disposed within the concentric cylindrical lattice 3. The lattice 3 has _an annular cap A ₀ and a cap G ₀ , respectively.
_G0 is insulated by a cylindrical ceramic member 4,
The cathode 2 has a structure insulated from the grating base _G0 and held by a cylindrical ceramic member 5.

Because it has a cylindrical structure, this electron tube is suitable for coupling with a cavity resonator, and the plate electrode has the advantage that the area of the anode can be increased, so the anode loss can be increased. Have it against the tube.

One of the factors that determines the high frequency limit of this electron tube is the existence of self-inductance in the electrode lead-in wire between the grating base G ₀ and the grid 3, and the electrode lead-in between the directly heated cathode terminal F ₀ and the cathode 2. There is a self-inductance of the line. The self-inductance increases as each lead-in wire becomes longer, and the voltage due to the self-inductance increases accordingly.

The present invention aims to substantially reduce the self-inductance to increase the frequency limit, as well as to increase the cooling efficiency of the electrodes and increase the grating loss.

FIG. 2 is an axial cross-sectional view of a concentric cylindrical electron tube as an embodiment of the present invention.

The structure of this electron tube is as follows. A concentric cylindrical grid 7 passes through the cylindrical anode 6, and the grid 7
has cylindrical caps G ₁ , G ₂ , and the caps G _{1 , G 2} .
G ₂ is insulated from the anode 6 by cylindrical ceramics 8 ₁ and 8 ₂ and fixed to the anode 6 at both ends thereof. Furthermore, two directly heated cathodes 9 ₁ and 9 ₂ pass through the grid 7, and each cathode has a cathode cap F ₁ , F ₂ and F ₃ , F ₄ , and the cap G ₁ and A cylindrical ceramic 10 ₁ is used between the cap F ₃ , a cylindrical ceramic 10 2 is used between the cap F ₃ and the cap F ₁ , and a cylindrical ceramic 10 ₃ is used between the cap _{G 2} and the cap F ₄ . Therefore, the cap F ₄ and the cap F ₂ are fixed substantially symmetrically on both sides of the anode 6 while being insulated from each other by the cylindrical ceramic 10 ₄ .

Compared to the electron tube shown in FIG. 1, the electron tube shown in FIG. 2 has the following features. Since the grating 7 passes through the anode 6 and has grating caps G ₁ and G ₂ on both sides of the anode 6, the degree of freedom in configuring the electric circuit increases and it is possible to configure circuits that were impossible with conventional electron tubes. can do.

For example, when using with grid grounding, the cap G ₁ and the cap
G ₂ can be coupled to ground with capacitances C ₁ and C ₂ respectively. Since the distance l ₁ between the base G ₁ and the base G ₂ is approximately proportional to the self-inductance of the grid electrode lead-in wire, the voltage due to the self-inductance can be reduced by grounding G ₁ and G ₂ via C ₁ and C ₂ . can be approximately half the voltage when only one of G ₁ or G ₂ is grounded. G ₁ or
Grounding only one of G ₂ via capacitance is equivalent to grounding G ₀ via C ₀ in FIG.

The anode current of an electron tube is approximately proportional to the effective opposing areas of the anode, grid, and cathode. Assuming that the anode currents of the electron tube in FIG. 1 and the electron tube in FIG. 2 are equal, the effective opposing areas of the anode, grid, and cathode of each are approximately equal.

In the electron tube shown in Fig. 1, the grating 3 can only be grounded (in terms of high frequency) at the base G ₀ , but in the electron tube shown in Fig. 2, the grating 7 can be grounded at the base G ₁ .
Since the base G ₂ can be grounded (at high frequency), the inductance of the electrode introduction wire in the electron tube of FIG. 2 is smaller than that of the prior art electron tube of FIG. 1. Therefore, it can be stably used at higher frequencies.

The lattice losses in electron tubes are limited by the temperature rise of the lattice. In the electron tube of FIG. 1, the temperature of the grid is cooled by G ₀ through the grid lead-in wires. On the other hand, in the electron tube shown in Fig. 2, the electron tube of the present invention is cooled by G ₁ and G ₂ which are arranged symmetrically, so the electron tube of the present invention has good cooling efficiency, has less grid emission, and has less lattice loss. You can take a lot of.

Although the electron tube in FIG. 2 shows an example of a triode having two directly heated cathodes, the present invention is not limited to triodes, but can naturally apply to multiodes such as tetrodes and higher. It can be implemented. Further, the cathode can also be easily made into an indirectly heated type. The directly heated cathode in Figure 2 is conceptually shown as two linear filaments, but its shape can also be modified into a cylindrical shape, a spiral shape, etc., or only one filament can be used. You can also use In the case of the preferred embodiment shown in FIG. 2, in addition to the advantage that all of the bases F ₁ , F ₂ , F ₃ , and F ₄ can be grounded (in terms of high frequency), for example, F ₂ and F ₄ can be shorted to Since current can be supplied from ₁ and _F3 , it has the advantage of having greater freedom in circuit design and implementation than the electron tube shown in FIG.

As described above, since the electron tube of the present invention has the grating bases G ₁ and G ₂ and the cathode bases on both sides of the anode, the self-inductance can be substantially reduced, and the cooling efficiency of the grating is high. This makes it possible to obtain a critical frequency and a large grating loss.

[Brief explanation of the drawing]

FIG. 1 is an axial sectional view of a concentric cylindrical electron tube according to the prior art, and FIG. 2 is an axial sectional view of a concentric cylindrical electron tube according to the present invention. 6...anode, 7...grid _{, 81,82} ...ceramics, _91,92 ...cathode, _{101 to 104} ...
... Ceramics, G ₁ , G ₂ ... Grid base, F ₁ ~
F ₄ ... Cathode cap.

Claims (1)

[Scope of Claims] 1. A cylindrical electron tube in which a concentric cylindrical grid is disposed within a cylindrical anode, and a cathode is disposed within the grid, in which the grid passes through the anode and A cap is provided on both sides of the anode, the cathode passes through the grid, a cap for the cathode is provided on both sides of the cathode, and a cylindrical cap is provided between the cathode and the grid and between the grid and the anode, respectively. An electron tube characterized by having shaped ceramics arranged therein. 2. The electron tube according to claim 1, wherein the cathode is a directly heated cathode. 3. The electron tube according to claim 1, wherein the cathode is an indirectly heated cathode. 4. The electron tube according to claim 1, wherein the cathode is two cathodes. 5 Claim 1, characterized in that the grating is a single grating and a triode is formed.
The electron tube described in section. 6. The electron tube according to claim 1, wherein the lattice is a double or more lattice to form a multiode tube.