Jan. 17, 1961 R. C. A. ELAND 2,968,742 HIGH EFFICIENCY TRIODE WACUUM TUBE Filed July 25, 1958 3

Home , Control grid, Pentode, Plate electrode

Jan. 17, 1961 R. C. A. ELAND 2,968,742 HIGH EFFICIENCY TRIODE WACUUM TUBE Filed July 25, 1958 3. Sheets-Sheet 1

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INVENTOR. M26a767 a.4.222W2 BY / ?%ael Jan. 17, 1961 R. C. A. ELAND 2,968,742 HIGH EFFICIENCY TRIODE WACUUM TUBE Filed July 25, 1958 3. Sheets-Sheet 2

INVENTOR. Mezaa27.2 AZ1/WA BY 22-62-4-2

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2,968,742 United States Patent Office Patented Jan. 17, 1961 2 tube in conjunction with a high efficiency output circuit 2,968,742 thereacross more efficient, as is fully described herein after. This advantageous gain is acomplished in the HIGH EFFICIENCY TRODEVACUUM TUBE present invention without increasing the noise factor, or Robert C. A. Eland, Arcadia, Calif., assignor to Standard 5 degrading other advantageous characteristics of the triode Coil Products Co., Inc., Melrose Park, Ill., a corpora vaccum tube. tion of Illinois As is well known in the art, a triode vacuum tube is essentially a diode to which a third or control electrode Filed July 25, 1958, Ser. No. 750,956 is added between the cathode and the plate electrodes for 5 Claims. (C. 313-293) 10 the purpose of controlling the flow of electrons to the plate. The control grid electrode is in the form of a screen or lattice, serving as an imperfect electrostatic shield. The control grid is usually operated at a negative This invention relates generally to triode vacuum potential with respect to the cathode, thereby controlling tubes, and more particularly relates to novel triode con 5 the number of electrons that pass between the grid wires struction that increases its overall gain performance and on their way to the plate electrode. efficiency in high frequency amplifier circuits. . Under such negative bias arrangement substantially Practical and commercial triode vacuum tubes have no grid current flows, and accordingly the amplification substantially lower dynamic plate resistances than those by the triode is with relatively low noise figure as com of tetrode and pentode vacuum tubes. The addition of 20 pared to any tube with a screen grid electrode. The the screen grid electrode in tetrode and pentode vacuum amount of electrons reaching the plate electrode under tubes substantially increases their dynamic plate resist usual charge-limited conditions is determined practically ance so that a typical RF output circuit connected to its by the electrostatic field in the cathode-to-grid space. output operates at optimum. - Once the electrons pass the grid electrode, they travel The susbtantially large dynamic plate resistance of 25 rapidly to the plate electrode, wherein space-charge screen grid tubes does not reduce the efficiency or over effects in the grid-to-plate space may be neglected. all Q of high frequency output circuits. The amplification factor of a triode is designated by The dynamic plate resistance of tetrodes and pentodes the constant mu. Mu is a measure of the relative effec is of the order of several hundred thousand ohms. On tiveness of the grid and plate voltages in introducing the other hand, the corresponding dynamic plate resistance 30 of triodes is of the order of thousands of ohms in typical electrotatic fields at the surface of the cathode, and is constructions, and at best, of the order of tens of thou accordingly a measure of the screening effect of the con sands of ohms. Thus a highly efficient or high Q output trol grid. The constant mu is determined by the geome circuit of a triode RF stage cannot attain optimum per try of the tube construction, and is generally independent formance due to the loading down effect thereon by the 35 of the voltages applied to the grid and the plate elec internal impedance of the triode tube connected there trodes. aCOSS The amplification factor depends primarily upon the In a given triode tube electrode configuration, the dy grid structure and construction, and is increased by what namic plate resistance may be increased by reducing the ever causes the grid electrode to more completely shield capacity between the plate and control grid electrodes. 40 the cathode from te plate. Closer spacing of the grid This correspondingly increases the amplification factor wires, or larger diameter grid wires, accordingly result in or mu of the triode tube. In tetrodes and pentodes such a higher mu factor. Also, an increase in the distance be interelectrode capacity reduction is accomplished by the tween the grid and plate electrodes produces a higher added screen grid electrode. In cascode circuitry of the amplification factor mu. For RF amplifiers, commercial type shown in the Nelson Patent 2,775,659, the second ly available triode vacuum tubes of prior constructions triode stage is connected as a grounded grid amplifier 45 have mu factors ranging from about five to about one to accomplish equivalent results. hundred. In the case of pentode and tetrode tubes, current In accordance with the present invention, I incorporate drawn by the screen grid increases the noise figure of the one or more shielding elements in the vicinity between tube, and accordingly Such tubes are inferior to triodes the control grid structure and the plate electrode. The where noise performance is important, as in television 50 shielding elements are made independent electrically of reception. In the case of television tuners in VHF range, the grid and plate electrodes, and arranged in a novel namely from 54 to 216 megacycles, the high dynamic manner to substantially lower the electrostatic control plate resistance of tetrodes and pentodes cannot all be effect that the plate exerts upon the cathode surface, with utilized in the RF stage due to the band width require out changing the effect that the grid has at the same point. ments. In the case of a single triode RF amplifier stage, 55 In other words, a larger change in plate voltage is there the available dynamic plate resistance in such tubes con upon required to exert a given electrostatic change at the structed heretofore is approximately 72 to /3 lower than cathode surface that the same triode requires without is requisite for optimum gain performance. such shield elements. The result is a higher amplifica In accordance with the present invention, the capacity tion factor, or mu, for the tube as will be hereinafter between the plate and control grid electrodes of a triode 60 set forth in detail. The dynamic plate resistance of the vacuum tube is reduced in a novel manner by a factor triode is correspondingly increased by these shield of two to three, to one. The dynamic plate resistance of elements. the resultant triode of the invention is thereby made suf In accordance with the present invention, the total ficiently high to perform in an amplifier stage to yield plate electrode structure is made larger than requisite for an overall gain comparable to that of tetrode, pentode 65 conducting the electron current of the triode. The active and cascode amplifier stages, i.e. where the transconduct portion of the plate structure is placed opposite the cath ance of the tubes is of the same order. ode and control grid electrodes, as heretofore, but with The interellectrode capacitance reduction between the the inactive plate portions extending therefrom. The plate and control grid electrodes correspondingly in shield elements are interposed between the grid electrode creases the dynamic plate resistance of the triode vacuum 70 and the inactive plate portions to electrostatically shield tube and renders the overall amplification action of the themreferred to accomplishto above. the increased mu and plate resistance 2,968,742 3 4. Such large plate structure is utilized to provide Figure 8 is an enlarged perspective view showing the ruggedness thereto, and prevent microphonics in the triode internal components of the triode of Figure 7. operation. Further, the larger or heavier plate structure Figures 9 through 14 are diagrammatic illustrations hereof, additionally affords adequate heat radiation to of several other forms which the triode of the present maintain a practical dissipation for the tube in operation. invention may assume in practice. There is no increase in the tube volume. The principles Figure 15 is a schematic electrical diagram of an RF of the present invention are applicable to triode structures amplifier circuit incorporating a triode vacuum tube of of various types, configurations, and sizes, as will be here the present invention. inafter set forth. Figure 16 is a diagrammatic representation of the tuned 0. output circuit of the RF amplifier stage of Figure 15. The added shield elements within the triode of the In Figure 1 is illustrated one embodiment of a triode present invention increases the electrostatic isolation be vacuum tube incorporating the principles of my invention tween the control grid and plate electrodes. This results herein. The triode vacuum tube 20 comprises an evacu in a substantially lower amount of oscillator voltage ap ated glass envelope 21. Mounted within envelope 21 is pearing on the grid electrode in a superheterodyne tuner a generally cylindrical plate structure 22, a central tu incorporating such triode in the input RF amplifier stage. bular cathode 23, and a helical grid structure 24 between Accordingly, when used in an RF or television tuner, ra plate structure 22 and cathode 23. The triode electrodes diation of oscillator signal from the antenna is reduced namely plate 22, cathode 23 and control grid 24, are significantly, particularly at the higher frequencies. anchored within the vacuum tube 20 in any suitable well The triode vacuum tube of the present invention is 20 known manner. accordingly eminently suited for use in high frequency The plate structure 22 comprises two active plate elec amplifiers, and in tuner circuitry such as for FM and trode surface portions 25, 26 exposed to control grid 24 television receivers in the first RF stage thereof. Its rela and cathode 23. The radial distance of active plate sur tively high gain, high efficiency, and low noise factor faces 25, 26 is closer to the cathode 23 than that of the makes it superior to pentode and tetrode amplifiers there 25 remainder of the plate structure 22. The plate structure fore, and comparable to the low noise but more expensive 22 is preferably fabricated of two similar semi-cylindrical cascode circuitry. Its ruggedness, freedom from micro Sections, joined respectively such as by spot welding along phonics, and ability to handle considerable signal levels, seams 27, 28. The shielding elements of triode 20 com makes it useful for most high gain RF circuits. prise two metallic cylindrical sections 30, 31 interposed It is accordingly a primary object of the present inven 30 between the inactive plate portions 32, 33 and the control tion to provide a novel triode vacuum tube of substan grid electrode 24. tially increased amplification factor, with corresponding The radial distance of the arcuate cylindrical shield increase of dynamic plate resistance. sections 30, 3i is made substantially equal to that of the Another object of the present invention is to provide active plate areas 25, 26. Shields 3G, 31 are arranged to a novel triode vacuum tube with electrostatic shielding 35 constitute an effective electrostatic shield between the elements interposed between the control grid and plate cathode 23 and control grid 24, particularly with respect electrodes to substantially reduce the interelectrode ca to the said inactive plate portions 32, 33. Shield elements pacitance therebetween. 30, 31 restrict the electrostatic field between the overall A further object of the present invention is to provide anode structure 22 and the control electrode 24 restricting a triode vacuum tube having novel internal electrostatic 40 the beam of electrons from the cathode 23 thereto by shielding between the control grid and plate electrodes directing more of the emitted electrons from the surface substantially reducing the interelectrode capacitance there of the cathode 23 to the active plate areas 25, 26. between, with corresponding increase in its amplification The shields 30, 31 are, in the preferred embodiment, and plate resistance. connected to the potential of cathode 23. These shields Still another object of the present invention is to pro 45 30, 31 of course may be connected to signal ground po vide a novel triode vacuum tube incorporating shielding tential, or to other comparable potential levels to effect elements to reduce the electrostatic field between the con the purposes of the present invention. The electrostatic trol grid and plate electrodes reducing the feed-back and shields 30, 31 shield the control grid 24 and its associated the neutralization requirements for such tube in high supporting members 34, 34 from the inactive portions 32, frequency amplification circuitry. 50 33 of the plate structure 22. Still a further object of the present invention is to Figure 2 is a perspective illustration of the arrangement provide a novel triode vacuum tube which is highly effi of the components of the triode 20 illustrated in Figure 1. cient as an RF amplifier stage when connected to a high The cylindrical cathode structure 23 is coaxial in the Q tuned output circuit, with a substantially improved tube 20 and the grid electrode 24 is wound in a helical resultant overall amplification. 55 arrangement about supporting pins 34, 34 (shown in Fig The above and further objects of the present invention ure 1). Mounting tabs 35, 35 extend from several edge will become more apparent in the following description portions of the anode structure 22 for securement with of exemplary embodiments thereof, taken in conjunction mica supports 36, 37 (Figure 3) within the tube. Simi with the drawings, in which: lar supporting tabs 38, 38 extend from the shielding plates Figure 1 is a diagrammatic view of one form which 60 30, 3i for mounting in supports 36,37. the present invention may assume in practice. Figure 3 illustrates the mutual supporting arrangement Figure 2 is a perspective illustration of the electrode of the electrode components of the vacuum tube hereof arrangement of the triode vacuum tube of Figure 1. within the evacuated glass envelope 21. Details of such Figure 3 is an elevational view of a triode vacuum tube arrangement are not shown, as they would be apparent corresponding to Figures 1 and 2. 65 to those skilled in the art. The upper extending tabs Figure 4 is a schematic electrical diagram of the internal 38, 38 of the shielding plates 30, 31 are electrically in components of the triode of Figures 1, 2 and 3. terconnected by a transverse bar 40 to establish a com Figure 5 is a diagrammatic view of a modified form mon potential for the shielding. One of the lower anode. of triode vacuum tube in accordance with the present 70 tabs 35 is connected by lead 42 to socket pin 41 extend invention. ing through the evacuated vessel 2. Similarly a lower Figure 6 is a partial perspective illustration of the tab 38 from the shields 30, 31 is connected to a socket internal components of the triode of Figure 5. pin 43 through lead 44. The grid electrode 24 extends Figure 7 is a further form of a triode electron tube through lead 45 to socket pin 46. The cathode 23 is in accordance with my invention, 75 connected to pin 48 through lead 47. The heater within 2,968,742 5 6 51,cathode 52 respectively. 23 is connected to pins 49 and 50 through leads are overcome by the invention structure. For high signal inputs, of the order of volts, with relatively heavier plate Figure 4 schematically illustrates the aforesaid electrode current necessary, the inactive plate portions or wings and shield connections to their respective socket pins. 32, 33 provide adequate heat dissipation. Also, a com The shield elements 30, 31 are preferably internally inter paratively high value plate current is usually required to connected, as through bar 40 (Figure 3) and as indicated give a reasonably good value of transconductance, with by the dotted line 53 in Figure 4. higher plate dissipation being used even at low level input Further, the interconnected shield elements 30, 31 may signals. be internally connected to the cathode 23, as indicated Figures 5 and 6 illustrate a variation of the structural by the dotted shorting lead 54. This would save the use O arrangement of the triode electrodes, wherein a basically of socket pin 43, but reduce the circuit flexibility for elliptical conformation is used in contradistinction to the utilization of the shield elements 30, 31. circular arrangement thereof of triode 29 of Figures 1 As is evident from Figures 1 through 4, an important to 4. The triode 60 comprises evacuated glass envelope result of the invention triode arrangement utilizing the 61 within which are suitably mounted an elliptical plate electrostatic shielding elements 30, 31 as set forth, is 15 structure 62 having reduced active plate sections 63, 64 that the electrostatic control effect exerted by the active radially closer to the central axis of tube 60 than the in plate areas 25, 26 at the surface of cathode 23 is lowered active plate portions 65, 66. The central cathode 67 is without changing the effect that the control grid 24 has generally rectangular in shape, with its wider dimension at the cathode surface. Thus, a larger change in plate in line with the longer axis of the elliptical plate struc voltage is required to produce the same electrostatic 20 ture 62. change at the cathode 23 surface as compared to that of The control grid 68 is elliptical in arrangement, con the same triode structure without the shields 36, 3i. forming with the elliptical pattern of the plate structure Mu is by definition dE--dE, with the plate current 62 as seen in Figures 5 and 6. The supporting pins 69, 69 constant. Eb and E are the plate and control grid po maintain the grid structure 68 in a helical pattern, seen tentials, and It is plate current. Mu is in effect a measure 25 clearly in Figure 6. The shielding elements 70, 71 of of a small change in plate voltige required to produce a triode 60 are segments of an ellipse, and extend across given electrostatic change at the cathode equal to that of the inactive plate portions 65, 66 as illustrated. The a correspondingly small change in the applied grid volt shields 70, 71 are coextensive with the inactive plate por age, for a constant plate current condition. Mu is the tions 65, 66 aforesaid, with their edges extending close effective amplification factor of the triode tube. How 30 to those of active plate portions 63, 64 to constitute an ever, since the shield elements 36, 31 thereof increases effective electrostatic shield between the control electrode the requisite dEb for the reasons stated above, it follows 68 and the inactive plate portions 65, 66 in a manner al that the mu of the tube 20 is increased by the electro ready set forth in connection with Figures 1 to 4. The static shields 30, 31. improved amplification factor and increased dynamic The plate resistance of a triode vacuum tube is desig plate resistance of triode 69 is comparable to that im nated by the Symbol r and is the dynamic plate re parted by the shielding elements of tube 20 hereinabove, sistance of an operating triode. The dynmic plate re and for same reasons, as will be understood by those sistance is a function of the effect of dE as it relates to skilled in the art. its effect on plate current. This relationship is as fol Figures 7 and 8 illustrate a further modification of lows: r=dEb-i-di. However, since more change in the 40 a triode incorporating the invention shielding elements, plate potential is required by the tube 29 due to shields with increased amplification factor mu and greater dy 30, 31 to produce the same change in plate current, the namic plate resistance afforded thereby, in accordance dynamic plate resistance r thereof is correspondingly with the principles of the invention hereof. The triode increased thereby. 75 of Figures 7 and 8 has a generally rectangular plate In practice, it has been found that the dynamic plate structure 76 arrangement. The active plate areas 77, 78 resistance r as well as the amplification factor mu of are flat surfaces parallel to the rectangular central cath triodes constructed with the arrangeinent hereof, in ode structure 79. Also, the grid structure 80 of tube 75 corporating a reduced active plate area (corresponding is of rectangular construction and incorporates a rigid to 25, 26), and shielding by shield elements (cor grid frame support. The active control grid wires 80 are responding to 39, 35) of the inactive plate portions (cor 50 accordingly parallel to the flat active anode surfaces responding to 32, 33), have been increased in practice 77,78. on the order of two to three times over that of unshielded It is to be understood that the anode structure 76 is in triodes. Such higher gain and plate resistance of the a tubular arrangement as illustrated in perspective in triode is accomplished without any increase in its noise Figure 8. It is preferably composed of two similar half figure, because no current is drawn through the signal 55 sections, spotwelded or otherwise affixed along their grounded shield plates 30, 31. Also, by using the inven abutting edges 81, 82. The active anode surfaces 77, 78 tion triode 20 across a tuned RF circuit, overall Q and extend inwardly from the basic anode structure 76, where performance efficiency of the circuit is substantially in in the inactive plate areas 83, 84 are shielded from the creased, with a resultant higher RF amplifier stage gain, control grid 80 and cathode 79 by the shield elements as is described in connection with Figures 15 and 16 60 85, 86. The shield plates 85, 86 are U-shaped, and are hereinafter. coextensive with the inactive plate areas 83, 84. The In view of the active portion of the anode structure 22, outer edges of the U-shaped shield members 85, 86 are namely the areas 25, 26, being a fraction of that of the proportioned to extend close to the edges of active anode whole anode structure 22, ruggedness and absence of areas 77, 78 as illustrated in Figures 7 and 8, to con microphonics is assured in the tube hereof. In other Stitute a significant electrostatic shield for the whole of words, by taking advantage of the volume within the the plate structure 76 with respect to the control grid 80, cylindrical tube envelope 25, the anode structure 22 is leaving exposed for action the active anode areas 77, 78 made substantially larger than the requisite active plate for the reasons set forth in detail hereinabove. The electrode area 25, 26 to impart ruggedness to the anode rigid grid support structure for the wound grid 80 com electrode as mounted between the mica supports 36, 37. 70 prises end vertical bars 87,88 joined by cross-bars 89,90. The anode structure 22 hereof also affords adequate heat Figures 9 through 15 illustrate still further geometric radiation surface for substantial dissipation due to cur forms and arangements which the internally shielded rent as the tube is utilized in conventional RF circuits. triode vacuum tube of the present invention may assume. For low signal inputs, namely in the microvolt range, In the triode vacuum tubes of Figures 9 through 14, the microphonics and stability are important factors which 75 plate structure assembly is formed in two separated sec 2,968,742 7 8 tions, which are separately mounted within the vacuum tube 140 through supporting pins 150. The two sections tube assembly and of course electrically interconnected of the plate assembly 141 are electrically interconnected, for common anode action, as will be understood. Such and establish a rigid mounting for the active plate plate structure division may be extended to three, four, areas 142, 43, as well as means for dissipating heat from etc. sections. the active plate areas during operation. In Figure 9, a generally rectangular arrangement for The inactive portions 146, 147, i48, 149 of plate the plate structure 96 of triode 95 is shown similar to assembly 141 are electrostatically shielded from the con that of Figures 7 and 8. The plate structure 96 has op trol grid 144 through shield members 151, 52, illus posed active anode areas 97, 98 extending centrally in trated as U-shaped. Members 151, 152 are coextensive wardly from the inactive wing portions 99, 100 of the 0. with the longitudinal extent of the plate assembly 141. anode structure 96. The plate structures of Figures 9 The ends of U-members 55, i52 extend close to the through 14, as well as the other components of the triodes edges of the flat anode members i42, 143 to effect the represented therein, are illustrated in diagrammatic form, substantial reduction in the capacitance between the con and are understood to be longitudinal and tubular in na rol grid 144 and the whole plate assembly 141. The ture, generally corresponding to the corresponding struc 15 shielding plates 153, 452 are connected to the cathode tures depicted, in perspective Figures 2, 6 and 8 herein 345 potential, or signal ground, as set forth hereinabove. above, and as described in connection with the triodes Figure 13 illustrates a form of the invention wherein 20, 60, 75 related thereto. the triode diagrammatically indicated at 60 contains The separated plate structure 96 is supported by pins two opposed rectangular tubular members 6, 162 con indicated at iti, for rigidity of mounting and elimination 20 stituting the plate assembly. The anode members 161, of microphonics. The central grid structure 102, and 162 are electrically interconnected (not shown) and internal cathode 103, are parallel to the flat active anode comprise active anode surfaces 163, 64 facing each Surfaces 97, 98. The U-shaped electrostatic shields 104, other. It is to be understood that the plate assembly 161, 105 are Substantially longitudinally coextensive with the 162 is longitudinal of the tube 60 and with the cathode tubular anode structure 96, and arranged to effectively 25 65 and control grid 166 constitutes the triode action. shield the wing or inactive plate structure portions 99, The central control grid-cathode assembly 165, 166 is 100 for reducing the electrostatic and capacitive char. parallel to the active anode plate portions i63, 164. The acteristics of the tube 95 between the grid structure 102 inactive portions of the plate assembly 16, 162 extend and the plate structure 96. The electrostatic shields 104, as hollow tubes behind the active anode surfaces 163, 164 105 are supported by the indicated mounting pins ibó, 30 to effectuate rigid mechanical structural mounting, and 106. avoid microphonics. Also, the tubular nature of the Figure 10 illustrates triode 120 having arcuate instead anode structure affords ample heat dissipation for the of plane wing and shield members. The plate structure active plate areas 263, 164. 111 thereof comprises flat central active anode portions The U-shaped shield members 67, 168 substantially 112, 113, with inactive wing portions 114, 15. The cen 35 minimize effective capacitance between the grid structure tral cathode 116 and grid electrode 117 are parallel to 166 and the anode structure 161, 162. The U-shaped the active anode members 112, 113 and coact therewith members 167, 68 have their edges arranged close to the as a triode amplifier. The semi-circular or arcuate shield edges of the active plates 163, 164, as shown. ing members 18, 119 are coextensive longitudinally with In this manner, the outward inactive portion of the the plate structure 111, and effectuate the electrostatic 40 plate structure 16, 162 is shielded from the grid 166 and shielding and capacitive minimization between the grid grid support bars 69, 70. Supporting pins 161 are used structure 117 and the inactive wing portions 114, 115 to mount shield members 167, 168. of the plate assembly is. Supporting pins i20 for the Figure 14 illustrates a form of the invention utilizing anode structure 511 and pins 12 for the shielding mem rugged active plate members 176, 177 for the triode 175 bers 118 and 119 are also provided. 45 illustrated diagramatically. The active plates 176, 177 In Figure 11 is illustrated a triode vacuum tube arrange are parallel to the central control grid 178 and cathode ment. 125 having two spaced plate anode members con i/9 to constitute a longitudinal triode assembly. The U stituting plate structure 26. The plate structure 126 shaped shield members 180, 18 extend close to the edges comprises central parallel active anode areas 127, 128 of the respective anode members 176, 177. Electrostatic with extending plane Wing portions 129, 130 which are 50 and capacitive relation between the control grid 178 and inactive in the triode electrical operation. The control particularly of its mounting posts 182, 183 with the anode grid 131 and central cathole 32 are parallel to the ac plates 176, 177 is materially reduced by effecting close tive anodes 127, 128. The shield members E33, 34 are spacing of the respective edges of the shields 180, 181 V-shaped and are coextensive longitudinally with the and the adjacent edges of anodes 176, 177. anode assembly 26. The shield members 133, 134 are 55 The electrostatic shielding is thereby maximized with arranged to electrostatically shield the control grid 3 a corresponding minimization of the capacitive value be and cathode 132 from the electrically inactive portions tween the control grid structure 178 and the plate struc of the anode structure 126 which includes the wing sec ture 176, 177, to in turn improve the amplification factor tions 129, 138 and the intermediate portions eXtending mu and the dynamic plate resistance of the triode 175. outwardly from the active anode plates 127, 128. Mount. 60 The shield members 180, 181 cut off the fields of electro ing rods 135, 136 are indicated for the shield members static force that would otherwise extend from the grid 133, 134. structure i78 including posts 182, 183, to the rear side In Figure 12, the triode vacuum tube 140 comprises a of the two plane anode plates 76, 177. In this manner, modified anode structure 141 which includes the flat the corresponding capacitance therebetween is minimized parallel central anode surfaces 142, 143 coacting with to effect improvement of mu and dynamic plate resist rectangular control grid .44 and central rectangular ance. The thickness of plates 76, 77 is made sufficient cathode 145 parallel thereto. The active anode plates to resist microphonics and dissipate the heat. 142, 143 are backed up and rigidly supported by T The application of a triode vacuum tube of the present members comprising outside plates 46, 47 with re invention in a high frequency RF amplifier stage is il spective transverse plates 48, 149 therebetween, as 70 lustrated in Figure 15. The RF amplifier 200 includes clearly illustrated. The anode plate structure 141 is un Such triode schematically shown at 201. An efficient derstood to be coextensive axially of the active portion high Q tuned output circuit is indicated at 202 incorporat of the vacuum tube elements, which includes the cathode ing a primary winding connected in shunt with a con 145 and control electrode 44 longitudinally of the tube denser 204, and a secondary output winding 205. The 140. The backplates 147, 148 are mounted within the 5 primary winding 203 connected to the active anodes of 2,968,743 9 10 tube 201 indicated at 206. The condenser 204 is signal level thereof on the grid 207. This is important in Super grounded as shown or may be connected to the tube heterodyne tuners such as VHF television tuners. cathode 208. The anode potential is supplied from The shield members 220, 221 are at cathode or at source B+ to primary 203. Stage 200 may be the first signal ground potential and no current is drawn by them. RF amplifier of a VHF television tuner, FM tuner, radar Hence, no internal tube noise is generated due to their set or other high frequency circuit section. presence. The noise factor of the invention triode 201 The control grid 207 is connected to the amplifier in in a high frequency RF amplifier is the same as that of put by lead 209. The input circuit 210 comprises primary conventional triodes. The overall resultant gain of the winding 211 coupled to secondary winding 212 with a RF amplifier stage 200 is substantially greater than with tuned condenser 213 in shunt therewith. The output and 10 a conventional triode with the same output circuit 202, input circuits 262 and 210 are tuned to the same frequency being comparable to the gain of tetrode, pentode and and band width for the signal amplification desired by cascode stages. The advantage of low noise factor makes stage 200. The tuned input circuit portion 212, 213 is it superior than tetrode and pentodes for low level signal connected to signal grounded, as shown, or to an AGC inputs, and for television reception; and its lower cost bias. The cathode 268 is self-biased through resistor 5 factor makes it more commercial than a cascode stage. 215 shunted by bypass condenser 216. The heater 217 A tube constructed in accordance with the present ofSupply. cathode 208 is suitably connected to a source of invention, with the shield members 220, 221 connected Triode 201 comprises the shield members 220, 221, to signal ground, compared with a conventional type schematically indicated. It is understood that shield 6BN4 triode as the input RF stage 2.00 in a VHF tele members 220, 221 correspond to those described herein 20 vision tuner as follows: The average noise signal pro above, as for example, shields 30, 31 of triode 20 of duced by the tuner was reduced by 1.5 db with the in Figure 1. Shields 70, 71 of triode 60 of Figure 5, etc. vention tube over the 6BN4; and the overall gain was The shields 220, 221 substantially reduces the capacitance doubled at the lower channels, and fifty percent greater between control grid 207 and the plate electrode 206 and at the higher channels. The normal plate voltage for substantially increases the mu and the dynamic plate 25 the 6BN4 was 135 volts, and was raised to 200 volts for resistance thereof, in the manner and for the reasons de the invention tube. The invention triode vacuum tube scribed hereinabove. As there is some residual capaci used herein had in one embodiment an amplification tance in the triode 201 between the active portion of plate factor or mu of 75 dynamic plate resistance of 8,000 206 and grid electrode 207 neutralization is still indicated ohms at 10 ma. plate current with a transconductance at high frequencies. Towards this end, a neutralizing 30 of 9,000 mhos, and a control grid to plate capacitance capacitor 225 is connected between the low potential of .038 upf. point of primary winding 203 and grid electrode 207. Although the present invention has been described in The shield members 220, 221 are connected to the cathode connection with exemplary embodiments thereof, vari 208 potential by respective leads 222 and 223 to point ations and modifications thereof within the broader spirit 224. 35 and scope of the invention will now be apparent to those skilled in the art, and it is not intended to be limited An important advantage of the triodes of my present except as set forth in the following claims. invention is their substantially higher dynamic plate re I claim: sistance as compared to comparable prior art triodes. In 1. A vacuum tube operable in the V.H.F. signal range this manner, when a tuned circuit is connected to the 40 with dynamic characteristics comparable to a triode com triode output its efficiency, its Q is substantially main prising a cathode electrode extending longitudinally of tained. Figure 16 schematically shows a tuned circuit the tube, a control grid electrode composed of a wire 230 comprising inductance 231 and condenser 232 in grid spaced from and substantially surrounding said parallel therewith. The conventional measure of the cathode electrode, a plate structure having an active efficiency of a tuned circuit is designated as Q. The more 45 anode portion supported opposite said wire grid and an efficient the higher the Q and the lower the internal re inactive plate section extending from each longitudinal sistance therein. Such internal resistance may be repre edge of said active anode portion, said inactive plate sented by a parallel resistance 233 across the tuned cir sections being more remotely spaced from the wire grid cuit 230, significantly higher in value. A high Q tuned than the active anode pcrtion spacing, and a shield circuit has a high impedance. The parallel impedance 50 member interposed between each of said inactive plate atL isresonance the inductance W is aof resistance coil 231. 233 equal to wLQ wherein sections and said grid electrode, each shield member Thus when the tuned circuit is connected to the output having an edge region substantially coplanar with said of a triode, as circuit 202 to plate 206 of tube 201 (Fig active anode portion and positioned close to a respective lure 15) the dynamic plate resistance of the triode is in longitudinal edge of the active anode portion for effec effect also connected across or in parallel with the tuned 55 tively inhibiting capacitance between said grid electrode circuit. This is indicated in Figure 16 by the dynamic and the inactive plate sections. plate resistance R in parallel with the equivalent circuit 2. A vacuum tube as claimed in claim 1, in which said 230 parallel resistance 233. It is thus evident that the plate structure is tubular in form and contains a second higher the value of this added resistance R, the higher 30 active anode portion supported opposite said wire grid the composite resistance effective across circuit 230. Thus in symmetrical relationship with the first said active anode the more efficient the tuned circuit and its voltage ampli portion, said inactive plate sections extending to and fication in the amplifier stage. being joined with said second active anode portion, and The effectively higher dynamic plate resistance of said shield members individually extending about said triode 29 in accordance with my invention thus results 65 control grid electrode in symmetrical relationship, each in a more effective utilization of the tuned circuit 202 of said shield members having second edge regions sub in the RF amplifier stage 200. Further, the increased stantially coplanar with said second active anode portion amplification factor or mu in the invention triode 201 and positioned close to a respective longitudinal edge additionally improves the signal gain through the ampli thereof. 70 3. A vacuum tube as claimed in claim 2, in which the fier 200. Finally, in view of the reduced capacitance be total area of said inactive plate sections is substantially tween the plate structure 206 and the control grid elec greater than the total area of said active anode portions, trode 207, any local oscillator or other signal on the whereby the effective capacitance between said control output side of the triode 201 results in a correspondingly grid electrode and the plate structure is reduced by a lower radiation from input side, or extraneous signal 75 substantial factor by said shield members and the dynamic 2,968,742 12 11 5. A vacuum tube as claimed in claim 4, in which plate resistance of the vacuum tube is correspondingly said plate structure contains a second integral planar increased. 4. A vacuum tube operable in the V.H.F. signal range active anode portion supported opposite said wire grid with dynamic characteristics comparable to a triode in symmetrical relationship with the first said active comprising a cathode electrode extending longitudinally anode portion, said second active anode portion being of the tube, a control grid electrode composed of a wire arranged in the interior tubular array with said shield grid substantially surrounding said cathode electrode, a members and in close proximity therewith. plate structure of tubular form surrounding said control grid, said plate structure having at least one planar active References Cited in the file of this patent anode portion extending integrally therefrom to a posi 10 UNITED STATES PATENTS tion closer to said wire grid than that of residual inac 2,396,170 Fulton ------Mar. 5, 1946 tive sections thereof, and shield members interposed be 2,877,374 Papp ------Mar. 10, 1959 tween said wire grid and the inactive plate sections, each shield member having an edge region substantially co FOREIGN PATENTS planar with said active anode portion and positioned close 15 282,712 Great Britain ------Mar. 15, 1928 thereto, said shield members extending about said wire grid to constitute with said active anode portion a tubular OTHER REFERENCES array within the tubular plate structure, whereby ca pacitance between said grid electrode and the plate struc Terman: Radio Engineer's Handbook, McGraw-Hill, ture is substantially reduced. 20 New York, 1943, pages 301 and 302 relied on. Notice of Adverse Decision in Sisterference In Interference No. 91,898 involving Patent No. 2,968,742, R. C. A. Eland, High efficiency triode vacuum tube, final judgment adverse to the patentee was rendered June 24, 1963, as to claim 1. Official Gazette February 4, 1964. Disclaimer 2,968,742-fobert O. A. Eland, Arcadia, Calif. HIGH EFFICIENCY TRIOpE

ACUUM. Tu BE. Patent, dated Jan. 17, 1961. Disclaimer filed Feb. 7, 1964, by the assignee, Standard Kolisman Industries Inc. --- Hereby enters this disclaimer to claim 1 of said patent. Official Gazette June 9, 1964.