US3125734A - Tuning screw having a double choke - Google Patents

Tuning screw having a double choke Download PDF

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US3125734A
US3125734A US3125734DA US3125734A US 3125734 A US3125734 A US 3125734A US 3125734D A US3125734D A US 3125734DA US 3125734 A US3125734 A US 3125734A
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Prior art keywords
choke
tuner
tuning
rod
assembly
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
    • H01P7/00—Resonators of the waveguide type
    • H01P7/06—Cavity resonators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J23/00—Details of transit-time tubes of the types covered by group H01J25/00
    • H01J23/16—Circuit elements, having distributed capacitance and inductance, structurally associated with the tube and interacting with the discharge
    • H01J23/18—Resonators
    • H01J23/20—Cavity resonators; Adjustment or tuning thereof
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J25/00—Transit-time tubes, e.g. klystrons, travelling-wave tubes, magnetrons
    • H01J25/02—Tubes with electron stream modulated in velocity or density in a modulator zone and thereafter giving up energy in an inducing zone, the zones being associated with one or more resonators
    • H01J25/22—Reflex klystrons, i.e. tubes having one or more resonators, with a single reflection of the electron stream, and in which the stream is modulated mainly by velocity in the modulator zone
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J25/00—Transit-time tubes, e.g. klystrons, travelling-wave tubes, magnetrons
    • H01J25/02—Tubes with electron stream modulated in velocity or density in a modulator zone and thereafter giving up energy in an inducing zone, the zones being associated with one or more resonators
    • H01J25/22—Reflex klystrons, i.e. tubes having one or more resonators, with a single reflection of the electron stream, and in which the stream is modulated mainly by velocity in the modulator zone
    • H01J25/24—Reflex klystrons, i.e. tubes having one or more resonators, with a single reflection of the electron stream, and in which the stream is modulated mainly by velocity in the modulator zone in which the electron stream is in the axis of the resonator or resonators and is pencil-like before reflection

Definitions

  • This invention relates generally to ultra high frequency electromagnetic apparatus and more particularly to a novel non-contacting tuning apparatus for utilization in wave propagating structures or external tuning cavity resonators for klystrons and the like.
  • Tuning assemblies now exist wherein tuning rods extend into the waveguides or cavity resonators without contacting the walls of the waveguide, the tuning rod being movably supported at a pointremoved from the place of entrance into the waveguide'.
  • at least two long-wearing bearing supports for the tuning rod be utilized, provided, however, that no metal-to-metal contacts occur at any portion of the assembly which carries R.F. current and which therefore could produce R.F. noise in the waveguide.
  • the object of the present invention to provide a novel vibrationless, long-wearing, smooth tuning, non-contacting tuning assembly constructed so as 'to eliminate all sources of metal-to-metal contact or bearing surfaces along the RF. current carrying portions of the assembly.
  • One feature of this invention is the provision of a novel tuner assembly having a capacitive tuning rod that makes no metal-to-metal contact with the waveguide or cavity resonator and which is supported in the tuner assembly in a manner such that there is no metal-to-metal Contact at any portion of the assembly which carries RF. current.
  • a further feature of the present invention is the provision of a tuner assembly of the above featured type having a novel lower and upper choke system which provides a radio frequency short circuit between the capacitive tuner rod and the waveguide or cavity resonator without metal-to-metal contact.
  • Still a further feature of the present invention is the provision of a non-contacting, double choke, capacitive tuner probe assembly using a dielectric sleeve in the lower choke as a radially loaded bearing having no metalto-metal contact with the tuner rod and a combination of graphited cast iron against stainless steel as an upper threaded bearing to accomplish axial motion for the tuner rod having very long life.
  • FIG. 1 is a longitudinal cross section view of a tuner assembly embodying the present invention
  • FIG. 2 is a partial cross sectional view of the lower choke and dielectric sleeve taken at 2 2 in FIG. 1,
  • FIG. 3 is a perspective view of the lower choke and FIG. 4 is a view of the present tuner assembly utilized in the external cavity resonator of a tunable klystron oscillator.
  • FIGS. l through 4 one embodiment of the present invention is shown mounted on a cavity resonator although it should be noted that the tuner may be utilized in other microwave circuits such as waveguides.
  • the cavity resonator body 1 is centrally apertured and counterbored from the top, the aperture 1 providing for the admission of a capacitive tuning rod 3 into the inner chamber 4 of cavity resonator 1.
  • the diameter of the capacitive tuning rod 3 is smaller than the 3,125,734 Patented Mar. 17, 1964 ice central aperture 1 so that there will be no metal-tometal Contact between the inner wall of cavity resonator 1 and capacitive tuning rod 3.
  • a radio frequency lower choke 5 formed by a hollow cylinder 5 made of, for example, silver plated steel having a anged bottom portion 5, the ilange portion 5 of lower choke 5 nestling in the base of the counterbore of cavity resonator 1.
  • Dielectric sleeve 6 made of, for example, Teflon is closely tted inside of lower choke cylinder 5' and acts as a bearing in which tuning rod 3 moves.
  • a flange 6' is provided for dielectric sleeve 6 to prevent dielectric sleeve 6 from slipping down inside of lower choke cylinder 5.
  • An upper choke 7 is formed by a counterbored hollow cylinder 7' provided with an outer shoulder 7, which is also tted into the counterbore of cavity resonator 1 making metal-to-metal contact with flange 5" of lower choke cylinder 5.
  • the inner step of the counterbore of upper choke cylinder 7 is adapted to accommodate liange 6 of dielectric sleeve 6.
  • a rubber gasket 8 is tted between the external wall of cavity resonator 1 and external shoulder 7" of upper choke cylinder 7 to permit hermetic sealing of the resonant cavity if so desired.
  • the inner diameter of upper choke cylinder 7 is larger than the diameter of capacitive tuning rod 3 so that there is no metal-to-metal contact between upper choke cylinder 7 and capacitive tuning rod 3.
  • Capacitive tuning rod 3 is held in position in dielectric sleeve 6 by deforming lower choke cylinder or member 5 and dielectric sleeve 6 such as to crimp inward at three places to obtain an approximate triangular shape so that when capacitive tuning rod 3 is forced into inner cavity chamber 4 through upper choke 7, dielectric sleeve 6, and lower choke 5, the deformed triangular shape of dielectric sleeve 6 will exert a radial resilient load on capacitive tuning rod 3.
  • the outer shoulder 7 of upper choke cylinder 7 accommodates the counterbore step of a two-stepped, hollow, counterbored tuner mounting sleeve 9 made of, for ⁇ example, stainless steel.
  • the upper portion of tuner ⁇ mounting sleeve 9 is internally threaded and has a small outwardly protruding lip 9', and the lower portion of mounting sleeve 9 has an apertured ilange for accommodating bolts 18 for fastening mounting sleeve 9 to cavity resonator 1.
  • a tuner assembly 10 made of graphite cast iron and having a central bored out lower portion for accommodating the upper end of tuning rod 3 by force fit, is provided to relate movement of tuner rod 3 into cavity chamber 4. This movement is accomplished through a threaded external lower portion of tuner assembly 10 mating with the internal threaded portion of tuner mounting sleeve 9.
  • a metal spring clamp 16 is provided around the exterior of theV threads to keep a radial load on the threads.
  • a slot 10' is cut in the top of tuner assembly 10 to accommodate a screw driver for rotating tuner assembly 10. This rotation, when transmitted to the threaded portion of tuner assembly 10, provides longitudinal movement to the tuning rod 3.
  • a built-in felt oiler ⁇ 11 is provided to lubricate the threaded surfaces of tuner assembly 10 and tuner mounting sleeve 9.
  • a silicone grease is used in felt oiler 11 as silicone grease is generally uneffected by temperature changes.
  • the graphited cast iron of tuner assembly 10 in conjunction with the stainless steel threads of tuner mounting sleeve 9 and the silicone grease in felt oiler 11 accomplish unusually long and low friction thread life.
  • the long wearing properties are due to graphite particles and iron particles from tuner assembly 10 smoothing both the threaded surface of tuner mounting sleeve 9 and the running surfaces of tuner assembly 10.
  • the graphite particles and iron particles are held in position by the silicone grease which of itself is a relatively poor lubricant.
  • the combination of graphited cast iron of tuner assembly l@ running against stainless steel threads of tuner mounting sleeve 9 gives a factor of 1t) improvement in life over, for example, stainless steel running against stainless steel.
  • the felt oiler 11 is held in position around tuner assembly by seals 12 and 13.
  • a rubber O-ring 14 is fitted around tuner assembly 16 for hermetic sealing of the tuner assembly.
  • tuner mounting sleeve 9 forms the upper bearing for the tuner assembly and is protected from dirt and dust particles by housing 1S, a metal cylinder having an inward flange 1S at the top and an apertured flange outwardly at the bottom.
  • housing 1S a metal cylinder having an inward flange 1S at the top and an apertured flange outwardly at the bottom.
  • the inward flange of the top of housing 15 along with metal seal 13 provides a housing for rubber O-ring 14 while lower flange of housing 15 is apertured for accommodating bolts 19 to secure housing 1S to tuner mounting sleeve 9.
  • Bolts 19 are fitted through apertures in the lower flange of housing 15 and are secured into taps drilled into tuner mounting sleeve 9.
  • a rubber gasket 17 is provided be tween the lower end of housing 15 and tuner mounting sleeve 9 for hermetic sealing.
  • the tuning rod 3 is supported at two places, the upper bearing or threaded por tion of tuner assembly 10 and tuner mounting sleeve 9 and by the radially loaded lower bearing consisting of lower choke cylinder 5' and dielectric sleeve 6.
  • lower choke cylinder 5 As lower choke cylinder 5 is deformed into triangular shape as best seen in FIG. 3, it springs radially to accommodate varying diameter of tuning rod 3 without allowing play in the lower bearing and, since the lower bearing is dielectric, there is no variable metal-to-metal contact to become noisy when tuning or noisy due to wear caused by tuning.
  • the upper end of lower choke 5 extends 1A: wavelength from the upper wall of the resonant cavity 4, this upper end being an open circuit by virtue of the physical short circ-uit at its lower end created by the ange 5" interconnecting the lower choke cylinder 5 and the lower end of upper choke cylinder 7.
  • the open circuit at the upper end of lower choke 5 is reflected a distance of M4 to provide an R.F. short circuit between rod 3 and upper wall of cavity 4.
  • This lower choke 5 is backed up by upper choke 7 which operates in the same manner as described -for the lower choke, the physical short circuit occurring at the upper surface of the shoulder 7" and the sleeve 9.
  • the novel tuner assembly is shown mounted on the external tunable cavity resonator 21 of a known type of internal-external cavity resonator reiiex klystron 22., this tuner providing substant-ially llonger life for the external cavity than previous tuners.
  • a high frequency tuning apparatus for varying the electrical characteristics of a wave propagating structure comprising a tuning rod movably extending into the wave propagating structure ⁇ through an aperture in the wall thereof without contacting the wall to elect tuning therein and support means for supporting said tuning rod on said wave propagating structure, said support means including a lower bearing formed by a dielectric sleeve and an upper bearing :formed by a tuner mounting sleeve threadably mating with screw threads on said tuning rod whereby a frictional bearing is -obtained between the mating threaded portions of the upper bearing and a sliding bearing is obtained at said lower bearing, a resilient choke member encircling said rod and serving to form a choke for said tuning rod and also serving to hold said dielectric sleeve in position around said tuning rod, and a second choke member encircling said rod and serving to form a second choke along said tuning rod and between the iirst choke and the upper bearing.
  • a thigh frequency tuning apparatus as claimed in claim l wherein said tirst choke member comprises an out-of-round metallic cylinder.
  • a high frequency tuning apparatus as claimed in claim l wherein said dielectric sleeve bearing is provided with a flange positioned at a point between said tirst and second choke members.
  • said second choke member comprises a multidiameter cylindrical member including a shoulder between the inner and outer diameters, the smaller diameter portion of said multidiameter cylindrical member serving with said tuner mounting sleeve to form the second choke, the shoulder of said multidiameter cylindrical member being positioned on ⁇ the ilange of said dielectric sleeve bearing, the larger diameter portion of said second choke member surrounding said iirst choke member in a spaced-apart manner thereby ⁇ defining the outer portion of said lower choke.
  • a tuning apparatus as claimed in claim 6 wherein the first cylindrical member comprises -an out-of-round metallic cylinder for resiliently pressing said dielectric sleeve against said tuning rod.

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  • Microwave Tubes (AREA)
US3125734D 1960-04-06 Tuning screw having a double choke Expired - Lifetime US3125734A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US2033060A 1960-04-06 1960-04-06

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US3125734A true US3125734A (en) 1964-03-17

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US (1) US3125734A (enrdf_load_stackoverflow)
DE (1) DE1186915B (enrdf_load_stackoverflow)
GB (1) GB930697A (enrdf_load_stackoverflow)
SE (1) SE313853B (enrdf_load_stackoverflow)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3720889A (en) * 1970-01-09 1973-03-13 Emi Ltd Electron discharge devices
US4122419A (en) * 1976-04-09 1978-10-24 English Electric Valve Company Limited Tunable resonant cavities having particular isolating choke
US20110102110A1 (en) * 2009-10-30 2011-05-05 Radio Frequency System Tuning element assembly and method for rf components
WO2020205546A1 (en) * 2019-04-01 2020-10-08 Marion Process Solutions, Inc. Modular microwave choke assembly

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2351895A (en) * 1940-05-11 1944-06-20 Allerding Alfred Electron tube device for ultra short waves
US2451876A (en) * 1943-06-05 1948-10-19 Winfield W Salisbury Radio-frequency joint
US2853678A (en) * 1953-11-16 1958-09-23 Sperry Rand Corp Millimeter frequency meter
US2946027A (en) * 1956-08-08 1960-07-19 Westinghouse Electric Corp Cavity resonator
US3016501A (en) * 1957-07-31 1962-01-09 Varian Associates High frequency probe apparatus
US3045146A (en) * 1959-03-18 1962-07-17 Eitel Mccullough Inc Tunable resonant cavity

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR964827A (enrdf_load_stackoverflow) * 1947-01-29 1950-08-25
NL208699A (enrdf_load_stackoverflow) * 1955-07-14
DE1038133B (de) * 1956-11-13 1958-09-04 Iapatelholdia Patentverwertung Abstimm- und Koppelanordnung bei einem Trioden-Oszillator fuer Mikrowellen
FR1252363A (fr) * 1959-03-18 1961-01-27 Eitel Mccullough Inc Cavité résonnante accordable et tubes électroniques utilisant une tetle cavité

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2351895A (en) * 1940-05-11 1944-06-20 Allerding Alfred Electron tube device for ultra short waves
US2451876A (en) * 1943-06-05 1948-10-19 Winfield W Salisbury Radio-frequency joint
US2853678A (en) * 1953-11-16 1958-09-23 Sperry Rand Corp Millimeter frequency meter
US2946027A (en) * 1956-08-08 1960-07-19 Westinghouse Electric Corp Cavity resonator
US3016501A (en) * 1957-07-31 1962-01-09 Varian Associates High frequency probe apparatus
US3045146A (en) * 1959-03-18 1962-07-17 Eitel Mccullough Inc Tunable resonant cavity

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3720889A (en) * 1970-01-09 1973-03-13 Emi Ltd Electron discharge devices
US4122419A (en) * 1976-04-09 1978-10-24 English Electric Valve Company Limited Tunable resonant cavities having particular isolating choke
US20110102110A1 (en) * 2009-10-30 2011-05-05 Radio Frequency System Tuning element assembly and method for rf components
US8269582B2 (en) * 2009-10-30 2012-09-18 Alcatel Lucent Tuning element assembly and method for RF components
WO2020205546A1 (en) * 2019-04-01 2020-10-08 Marion Process Solutions, Inc. Modular microwave choke assembly

Also Published As

Publication number Publication date
GB930697A (en) 1963-07-10
DE1186915B (de) 1965-02-11
SE313853B (enrdf_load_stackoverflow) 1969-08-25

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