'Sept._ 24, 1946.__ ' A, H] TURNER‘ I . 2,408,355 ' CONCENTRIC LINE OSCILLATOR. Filed Jan. 29, 1942 16- i- - _ * f1 H407 "I "if ———:;—-—— . ‘ 2 Sheets-Sheet 1 'l'UN/IBLL' LIA/E A /1-9 . Tu/MBLE/ LIA/E v <~ Zmventor Alfred if. Turnerv @w Gttorneg \ Sept; 24,!1946. A_ H, TURNER ‘ ' 2,408,355 ’ CONCENTRIC LINE OSCILLATOR Filed Jan. 29, 1942 > 2 Sheets-Sheet‘ 2 48 r I F116;;- I r .34 a1 ———— -— _' _____ ___V__" a‘ 22 32 3nventor ' r? II. 'lurner I _ Gttomeg Patented Sept. 24, 1946 2,408,355 UNITED STATES PATENT OFFICE 2,408,355 CONGENTRIQ LINE OSCILLATOR Alfred H..Turner, Collingswood, N. J., assignor to Radio Corporation 01’ America, a corporation of Delaware Application January 29, 1942, Serial N91 438.4565, 5 Claims. 1 (01. zsoe-ss) 2 My’ invention relates to vacuum tube. oscillators on the drawings are for a particular tube. The for producing, radio frequency energy having cathode, grid and plate are indicated by the ref erence characters ll, l2 and 13, respectively. short wave lengths such. as Wave lengths in the centimeter wave region. ‘ The oscillator circuit basically is of the well _It is sometimes desirable to employ triodes or known “grounded grid” type, although, in ac cordance with the present invention, the grid I2 other multi-element vacuum tubes rather than magnetrons or the like for producing very high frequency energy. Triodes and similar vacuum tubes have been specially designed for high. fre is connected through a capacitor I4 to ground. The capacity of element I4 depends upon the cir .Astill further object of‘ the invention is to ‘pro Fig? 2 shows ‘a preferred construction of the cult and particular tube employed, but usually quency use, but for some applications it has been will be somewhere between 14 mmf. and 100 mmf. found’di?icult to make them oscillate at a high 19 A grid leak resistor 16 is connected across ca enough frequency. " > pacitor Ill. The plate I3‘ is connected to one con One object of ‘my invention is to provide an im ductor of a line ll—|8, which maybe tuh'ed'by proved oscillator tor producing very high. fre means of a capacity changing element t9 to ad quencyeuergy- ' " 15 just the‘ oscillator frequency The cathode II is A Vfurther object Qf‘th? invention is to provide connected to one conductor 'of a line 2 |'—22 which an improved triode Oscillator for. producing high may be tuned by! means of a shorting bar 23. frequency energy vide an improved oscillator of the ‘-‘grounded 20 oscillator QVf'I‘F‘lgJ 1. The cathode,’ grid and plate terminals of the tube ID are shown at- ll’, 12’, grid” type. v ' In a preferred embodiment of the invention, there is employed a triode so designed as to reduce and I3’, respectively. The grid terminal I2! is the edge of a washer-shapedpiece of metal sup spectively. comprising concentric conductors. on a metal disc I5 sealed to the upper glass sec tion. The cathode terminal portion l I’ is a metal porting the ‘grid and sealed to 'glas-ssections indi the electron transit time and the interelee-trode cated as such by the shading.‘ The plate termi capacitiesto a minimum. The plateand cathode 2.5 nal plug'l3’ and the plate itself are supported are connected to two tunable circuits or lines, re The grid would be grounded if usualpractice were followed, but it has been found that Oscillations can be obtained at a higher frequency if the grid 30 is connected through some capacity to ground. lead is shown at 25. The cathode and the other side of-rthe cathode heater are connected through This capacity provides feedback coupling" which functions in' phase with the ‘feedback through the plate-cathode tube capacity to maintain high fre The tunable line 2l—2‘2 comprises two concen tric cylinders, the outer cylinder. 22 being fastened at the bottom by bolts 29 to the bottom plate 28 shell forming the tube ~base. ‘One cathode heater a plurality of‘ parallel lead-s 27 to a metal disc 28. quency oscillations. 35 and. being fastened at the top in screw-threaded The invention ‘will be betterunderstood from relation to a metal cap portion 3|. The inner the following description, taken in connection cylinder ‘21 is supported at the bottom by an out with the accompanying drawings in which turned edge soldered to outer disc 28. The upper Fig. 1 is a circuit diagram of a preferred 'em edge of cylinder 2|. is slotted to form ?ngers that bodiment of the invention, Fig. 2 is a side view, partly in section, of the oscillator shown schematically in Fig. _1 (the. view being drawn two times full scale), 40 make electrical contact with the cathode through the terminal I 1-’. The shorting bar 2.3 comprises a ring surround ing the cylinder 2] and having ?nger-s that make Fig. 3 is an enlarged view taken on the ‘section contact therewith and having other ?ngers that 3—3goi'Fi_g. 2, and 45 make contact with the outer cylinder 22. This Fig.4 illustratesranother embodiment of- the ring or shorting bar 23 may beslid along the invention. cylinders 2| and 22 by means of rods 320i in ‘In the several-?gures, like parts are indicated sulating material extending through openingsin by like reference characters. the bottom plate 28. ‘In Big. 1 the oscillator comprises a triode H1 50 The tunable line l'l-l 8 alsocomprises two con, designed to have every small inter-electrode ca centric metal cylinders. ‘In the speci?cstructure pacities C1,‘ C2 and C3. The particular vacuum tube that is illustrated and described by way of exampleis the General Electric type ZP446. The valuesof the tube capacities C1, C2 and C3 given shown, the cylinders .I1 and 18 are enclosed by a protective cylinder 33 which is supported at the bottom by means of a metal cup-shaped mem 55 ber 34 which it engages inscreW-threaded rela 52,408,355 3 tion. The cup member 34 and the cap member 3i preferably are also ‘welded or soldered together. The cylinder 18 of the line l'l--l8 preferably is 4 a contacting ring 66 and the capacity between the ’ ring 66 and'the end of cylinder 62, the ring and cylinder being separated by a mica washer 61; soldered or welded to the cup member 36 and is given further mechanical support by a surround ing ring 36 that is bolted to the bottom of mem ber 34 by several bolts 31, only one of which is shown in the drawings. and the cylinder 63 is coupled to the anode ter minal l3’ by coupling-capacity at the spacing provided by an insulating bushing 58. The anode and cathode circuits may be tuned by shorting bars indicated at- 59 and ‘H, respec tively. The cylinder 11 is supported from the cylinder From the foregoing, it will be apparent that I 10 l8, by mean-5 of studs 38 of insulating material, have provided a simple oscillator employing a only one of which is shown, each stud 38 being comparatively small and inexpensive vacuum fastened in screw-threaded relation to the cylin tube that, because of the presence of the capacity der IR. A spacing washer 39 .of insulating mate l4 between grid and ground, may be made to rial is located between the two cylinders H and 18. oscillate at a higher frequency than is possible The lower end of cylinder I‘! is electrically con 15 if the plate-cathode capacity C1 alone is depended nected to both the upper plug portion 13' and the ' upon to provide the necessary feedback. supporting disc portion I5 of the anode terminal I claim ‘as my invention: by means of contacting rings M and (i2, respecl. ' 1. An oscillator comprising a vacuum tube hav tively, having contacting ?ngers thereon. Con ing a cathode, a control grid and an anode, a 20 nection" is made from the anode terminal to a tuned circuit having one terminal connected to plate voltage source (not shown) through a con said anode and having the ather terminal con ductor 43 and through a choke coil 44 and a con nected through a capacity element to said grid,‘ ductor 46 supported in and insulated from a metal and a second tuned circuit having one terminal tube 41. connected to said cathode and having the other’ The line tuning element I9 is a ‘metal block , terminal connected through said capacity ele-v containing a circular slot so that it is, in effect, ment to said grid whereby regenerative feedback " a. cup that may be moved into the space between cylinders I’! and E8 to change the capacity be is provided both by the anode-cathode ‘capacity As shown in Figs. 2 and 3, the capacity id be tween the tube grid and ground is provided be minal connected through a capacity element to tween the inner periphery of vthe cap 3| and a metal ring or triangular shaped member 5|, the surfaces of, the two elements being spaced apart the proper amount by a mica washer 52. other terminal connected through said capacity element to said grid whereby said capacity ele-' of said tube and by said capacity element. tween them. The tuning cup I9 is supported on 2. An oscillator comprising a vacuum tube hav-. an insulated rod 48 which is supported in screw 30 ing a cathode, a control grid and an anode, a threaded relation in a disc 49 fastened into the tuned anode circuit having one terminal con end of the cylinder l8. ' nected to said anode and having the other ter-. said grid, and a tuned cathode circuit having one terminal connected to said cathode and having the ment is common to said anode and cathode The grid terminal I2’ is connected to the ring -_ circuits to provide regenerative feedback which 5! through a, contacting ring 53 having contact 40 aids that provided by the anode-cathode capac ing ?ngers thereon. The resistor I6 is con ity of said tube. nected between the ring 5| and the cap 3|. 3. An oscillator comprising two pairs of con-' The ring 5! is supported by the bolts_3'| which ductors which are isolated from each other by a extend through the tab portions extending from partition of conducting material, a vacuum tube the ring. Insulating bushings 54 prevent having anode, cathode and control grid terminals, grounding of ring 5i; they also provide ‘the said anode terminal being connected to one con proper spacing to hold the washer 52 and the ductor of one of said pairs, said cathode being contacting member 53 in place but,_at the same connected to one conductor of the other of said time, permit member 53_ to move laterally a slight amount when a tube is inserted whereby it will 50 pairs, the other conductors of said pairs and said be aligned for better contact. , The specific oscillator illustrated in Fig. 2 is designed to oscillate at 3,000 megacycles (10 centimeters). The frequency is determined prin cipally by the line l1~—l8 as tuned by the cup [9 and to a less extent by the line 2l—-22, the posie partition being conductively connected to each other, and means for capacitively coupling said grid terminal to said partition whereby there is provided additional regenerative feedback cou pling to aid the coupling provided by the anode cathode capacity of the tube. 4. An oscillator comprising two pairs of con centric conductors which are positioned end-to end along a common axis, a centrally apertured tion of the shorting bar 23 on the line 2l-22 not being very critical. Since the line 11-48 would be too short for convenient mechanical portion of conducting material separating said construction at such a high frequency if made 60 two pairs and connected to one conductor of each a quarter wave length long, it is made three of said pairs, a vacuum tube having anode and quarters of a wave length long in the example described. In Fig. 4 there is shown an embodiment of the ‘ cathode terminals at opposite ends and having a control grid terminal positioned intermediate the invention in which the outer cylindrical member 65 other tube terminals, said anode terminal being connected to the other conductor of one of said 6! which forms part of the tuned cathode circuit pairs, said cathode being connected to the other surrounds the other cylindrical members 62 and conductor of the other of said pairs-and means 03 that form the tuned anode circuit. In this construction the cylinder 62 functions as one ' side of each tuned line. or tuned circuit and also functions as a portion which isolates the two for capacitively coupling said grid terminal to said partition whereby there is provided addition al feedback coupling between said pairs of con ‘ductors. , tuned circuits. 5. An oscillator comprising twov pairs of con The cylinder BI is connected to the cathode centric conductors which are positioned end-to terminal I!’ by contacting ?ngers 64; the cylin der e2 is coupled to the grid terminal l2’ through 75 end along a common axis to form a tuned anode 2,408,365 5 , circuit and a tuned cathode circuit, a centrally apertured portion of conducting material isolat ing said tuned circuits and connected to one ter minal of each of said tuned circuits, a, vacuum tube having anode and cathode terminals at op posite ends and having a control grid terminal positioned intermediate the other tube terminals, said anode terminal extending through said aper ture and being connected to the other terminal 6 ‘of said tuned anode circuit, said cathode termi nal being connected to the other terminal of said tuned cathode circuit, and means for capaeitively coupling said grid terminal to said partition whereby there is provided additional regenerative feedback coupling from said anode circuit to said Cathode circuit. ' ALFRED H. TURNER.