US2894165A - Flanged anode for beam power tubes - Google Patents

Description

July 7, 1959 D. sAY' I 2,894,165

FLANGED ANODE FOR BEAM POWER TUBES Filed Oct. 17, 1956 INVENTOR DO NA L D SAY BY W/7 ATTORNEY United States Patent FIJAN GED ANODE FOR BEAM POWER TUBES Donald Say, Brookville, Pa., assignor, by mesne assignments, to Sylvania Electric Products Inc., Wilmington, Del., a corporation of Delaware Application October 17, 1956, Serial No. 616,471

4 Claims. (Cl. 313-217) This invention relates to beam power tubes and in particular to the structural form of the anode to adapt it for better association with other electrodes within the tube to attain better operation of the tube.

This type of tube, like a pentode, has a family of platevoltage vs. plate-current curves, with different control grid voltages, characterized by a sharp rise in plate current with initial increase in plate voltage and a subsequent fairly flat portion with increasing plate voltages. At the juncture of the two portions of the curve, a sharp bend or knee occurs. When this knee is at high plate potential levels, the tube gives rise to RF radiations. In a television set such RF radiations may be picked up by the antenna or parts adjacent the tube, and transmitted through the set, giving :rise to dark vertical lines at the right hand side of the picture tube, these lines being known in the art as snivets. At lower plate potential levels of the knee such conditions do not arise.

It is an object of this invention to prevent the occurrence of these snivets by creating a beam power tube with a lower knee characteristic. In applicants construction the lowering of this knee is effected by forming portions of the anode which are positioned within the beam confined area with extensions at the margins of the beam confined area and directed toward the control grid.

It is therefore an object of this invention to provide an anode structure which shall enable the tube to operate with low potential applied to the anode so as to prevent creation of undue RF radiations.

It is a further object of the invention to provide in a beam power type of electron tube a structure which while not appreciably decreasing the plate resistance of the tube shall efiect a substantial lowering of the potential at which a sharp change in the voltage-current curve occurs, i.e., a lowering of the knee of the curve.

These and further objects of the invention will be made apparent by consideration of the following description in conjunction with the accompanying drawings in which:

Fig. l is an elevation of a mount disclosing the position of the anode with respect to laterally positioned beam confining plate portions.

Fig, 2 is a cross section on the line 2--2 of Fig. 1, with parts rotated 90,

Fig. 3 is a perspective view of the anode of the invention,

Fig. 4 is a perspective view of a beam confining plate.

Referring to the drawings in greater detail, at there is shown a mount of the beam power tube type and which includes a cathode 12, control grid 14, screen grid 16, beam confining plate and shield 18, anode 20 and getter 22, the whole being mounted on a stem 24. The mount is of conventional construction except for the configuration and location of the anode.

The anode of the invention is comprised of two channels 26 and 28 joined by an arcuate strap 30. The channels and strap are reinforced by corrugation 32 running transversely of the channels and longitudinally of the strap, the channels being further reinforced by corrugations 34 on the webs of the channels, perpendicular to the corrugation 32 and substantially centrally of the webs. Each of the channels 26 and 28 has its flanges 36 and 38 perpendicular to the web of the channel with the strap merging into the flanges 36 substantially midway of their lengths. The flanges 38 have free edges while the flanges 36 are free along their edges except where the strap 30 adjoins the edges. The overall transverse dimension of the channel is slightly less than the spacing between leg portions 40, 42 of the plate 18. In Fig. l the projected spacing between the channel 28 and the legs 40, 42 is exaggerated; in actual practice the spacing of the channels from the legs would be so close that the grid wires would be barely discernible in this projection and the flanges Would be at the margins of the electron beam but not in the shadow of the beam behind the plate 18. In order to efiect lowering of the knee it is important that the flanges of the channels extend toward the grids in a position where they are within the confines of the electron beam as the beam transverses the space between the legs 40, 42 of the plate 18. The channels are provided with lugs 44 for securing the anode between the conventional insulating spacers.

While the provision of flanges on the two sides of the channel is primarily for the purpose of effecting the lowering of the voltage at the knee of the voltage current curve and without substantial decrease in plate resistance, the flanges do materially increase the rigidity of the anode, especially when hot, as in use of the tube. As an example of the efiicacy of the invention, it was found that when a number of conventional beam power tubes, type 3CB6 were compared with a number of similar tubes but with flanged anodes wherein the flanges were located in a projected view between legs of the beam confining plate, the knee voltage at zero bias on the grid with the flanged anodes showed a decrease of 16 percent, while the plate resistance decreased only 5 percent.

Having thus described the invention what is claimed as new is:

1. An electron tube comprising a cathode, a control grid, a screen grid, a beam confining plate and an anode, the beam confining plate having laterally spaced apart portions and the anode being of a width slightly less than the spacing between said spaced apart portions and having at least one flange extending toward the grids, said flange being in the projection of the space between said spaced apart portions.

2. An electron tube comprising a cathode, a control grid, a screen grid, a beam confining plate and an anode, the beam confining plate having laterally spaced apart portions and the anode being of a width slightly less than the spacing between said spaced apart portions and having edge flanges extending toward the grids, said flanges being in the projection of the space between said spaced apart portions.

3. An electron tube comprising a cathode, a control grid, ,a screen grid, .a beam confining plate and an anode, the beam confining plate having laterally spaced apart portions and the anode being of a width slightly less than the spacing between said spaced portions and having at least one free flange extending toward the grids, said flange being in the projection of the space between said spaced apart portions.

4. An electron tube comprising a cathode, a control grid, a screen grid, a beam confining plate and an anode, the beam confining plate having laterally spaced apart portions and the anode being of a width slightly less than the spacing between said spaced apart portions and having substantially free edge flanges extending toward the grids, said flanges being in the projection of the space between said spaced apart portions.

References Cited in the file of this patent UNITED STATES PATENTS Joy Oct. 31, 1950 Elston July 22, 1952 OTHER REFERENCES

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