US3593245A - Double-tuned intermediate-frequency transformer - Google Patents

Double-tuned intermediate-frequency transformer Download PDF

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Publication number
US3593245A
US3593245A US815915A US3593245DA US3593245A US 3593245 A US3593245 A US 3593245A US 815915 A US815915 A US 815915A US 3593245D A US3593245D A US 3593245DA US 3593245 A US3593245 A US 3593245A
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United States
Prior art keywords
core
tuned
center
double
tuned intermediate
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Expired - Lifetime
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US815915A
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English (en)
Inventor
Kazutomo Iwata
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Panasonic Holdings Corp
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Matsushita Electric Industrial Co Ltd
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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H7/00—Multiple-port networks comprising only passive electrical elements as network components
    • H03H7/01—Frequency selective two-port networks
    • H03H7/0153—Electrical filters; Controlling thereof
    • H03H7/0161—Bandpass filters
    • H03H7/0169—Intermediate frequency filters
    • H03H7/0184—Intermediate frequency filters with ferromagnetic core
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F17/00—Fixed inductances of the signal type 
    • H01F17/04—Fixed inductances of the signal type  with magnetic core
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H7/00—Multiple-port networks comprising only passive electrical elements as network components
    • H03H7/01—Frequency selective two-port networks
    • H03H7/17—Structural details of sub-circuits of frequency selective networks
    • H03H7/1741—Comprising typical LC combinations, irrespective of presence and location of additional resistors
    • H03H7/1775—Parallel LC in shunt or branch path

Definitions

  • a double-tuned intermediate-frequency transformer having a structure wherein two single-tuned intermediate-frequency transformers employing cap-type cores provided with center cores therein are arranged adjacent to each other being covered with one shielding case, and being adapted to a free choice of the degree of coupling between the respective coils of the two single-tuned intermediate-frequency transformers laid adjacent to each other through adoption of the cap-type cores each having a suitable sleeve length relative to the length of its center core.
  • a double-tuned intermediate-frequency transformer hitherto placed on the market carrying a description noted for use in a transistor circuit is of a miniaturized type, and most of the double-tuned intermediate-frequency transformers have a structure wherein two single tuned intermediate-frequency transformers are arranged adjacent to each other and the combination thereof is enclosed in one shielding case.
  • one type is an L-couplcd one wherein a portion of one coil L is wound together with the other coil L, to obtain the coupling between the two coils as is shown in FIG. 6a, while, the other is a C-coupled one wherein respective higher potential points of primary and secondary sides are connected with each other through a capacitor C as is shown in FIG. 6b.
  • the present invention is intended to eliminate the abovementioned existing drawbacks.
  • the magnetic coupling is adapted to be obtained through the construction itself of a double-tuned intermediate-frequency transformer, and especially its degree of coupling can be easily varied by small changes in value.
  • either a core supporter or a center hole of a terminal plate is provided with a thread so that both members may be threadedly engaged with each other, and manufacturing efficiency can be remarkably increased as compared with a manufacturing method by which a core itselfis to be threaded.
  • a cap type core is rotated under an external force. Even if a distortion force may be applied to a center core of the cap type core in this case such a distortion force may be absorbed by the core supporter thereby preventing the center core from being damaged.
  • FIG. I is a sectional view of an embodiment of the doubletuned intermediate-frequency transformer according to the present invention.
  • FIG. 2 is a perspective disassembly drawing showing the construction of a single-tuned intermediate-frequency transformer comprised in the above double-tuned transformer;
  • FIGS. 3a to 3c are sectional views each showing respective examples of the cap type cores provided with center cores therein to be employed in the above double-tuned transformer;
  • FIG. 4 is an electric circuit diagram of the above doubletuned transformer
  • FIG. 5 shows performance characteristics each according to the respective combinations of the cap type cores shown in FIGS. 30 to 3c being employed in the above double-tuned transformer;
  • FIGS. 6a and 6b are electric circuit diagrams of conventional doubleduned intermediate-frequency transformers.
  • l designates a terminal plate provided with a tapped hole 2 at its center and a winding portion 4 for a coil 3 at its upper portion.
  • the tapped hole 2 in the terminal plate I is perforated therethrough, and a shank por tion 6 of a core supporter 5 made of thermoplastic resin or the like is engaged therein through a self-tapping method. That is to say, a plurality of ridges 7 to be threaded thereon are provided axially on the peripheral surface of the shank portion 6, which ridges 7 are put into the tapped hole 2 of the terminal plate I being turned round and threaded by themselves, thus being self-tapped, if expressed by the word used above.
  • a flange 8 at the upper end of the shank portion 6 of the core supporter 5 is provided with two protrusions 9, from which flange 8 down to the shank portion 6 thercthrough formed is a hole portion 10.
  • the core supporter 5 having such a construction is united with a cap type core 12 having a pot shape and a center core ll at its center portion.
  • two perforations 13 are provided in the top wall of the cap type core [2, each of the perforations being placed at the respective positions opposite to the protrusions 9 on the above core supporter 5, and the above protrusions 9 are inserted into the perforations 13 respectively, then, the protrusion tips are welded by fusion thereby uniting the core supporter 5 and the cap type core 12 with each other.
  • the center core II in the above cap type core [2 is fitted into the hole portion 10 in the core supporter 5, and an adjusting slot 14 is formed on the top surface of the cap type core 12.
  • Terminal pins l5 are embedded in the above terminal plate 1, and the terminal plate 1 is also provided with outlet slots 16 for lead wires.
  • a double-tuned intermediate-frequency transformer such as shown in FIG. 1 can be obtained by arranging two singletuned intermediate-frequency transformers each having a structure such as described above adjacent to each other and covering them with one shielding case I7.
  • FIG. 1 designates tuning capacitors which are disposed within hollow portions 19 provided in the bottom surface of the terminal plate 1.
  • Numeral 20 designates adjusting window portions provided in the upper wall of the shielding case I7.
  • the electric circuit of the double-tuned intermediatefrequency transformer having such a structure is shown in FIG. 4.
  • FIG. 3 sections of the cap type cores l2 to be employed here are shown.
  • the magnetic flux induced by one of the coils is magnetically shielded to a considerable extent by the comparatively long sleeve 12', therefore, the magnetic leakage flux which goes out of the cap type core is comparatively small.
  • the cap type core 12 shown in FIG. 3c is employed as in the above case, the magnetic flux induced by one of the coils passes from the tip of the center core II to the lower end of the sleeve 11', however, the magnetic flux path is more open compared with that in the case of H0. 30, hence, the magnetic leakage flux is considerably large.
  • the degree of coupling between the primary and secondary coils varies depending on the respective quantities of both magnetic leakage flux.
  • This phenomenon is being utilized in the intermediate-frequency transformer according to the present invention. Then, if an operating Q value is given for each coil, the pass band width as of the double-tuned intermediate-frequency transformer can be freely determined by changing the length of the sleeve portion 12' of the above cap type core [2, corresponding to the pass band width to be desired.
  • cap type cores l2 shown in FIGS. 30 to 30 are employed combining each two cap type cores of the same type in pairs, in regard to the pass band width as of the doubletuned intermediate-frequency transformer, that of the FIG. 3b type is wider than that of the FIG. 30 type and that of the FIG. 3c type is still wider than that of the FIG. 3b type.
  • the above response characteristics are shown in FIG. 5 being compared with each other.
  • the double-tuned intermediate-frequency transformer ac cording to the present invention being so constructed as described above, the degree of magnetic coupling between primary and secondary coils thereof can be chosen freely in practical use through adoption of any cap type cores chosen freely from those having various shapes. Moreover the structure of each coil in an embodiment according to the present invention can be made simple and easy to manufacture. Furthermore, the present invention can have other individual components such as required in a conventional C-coupled type, thus bringing about another advantage in cost reduction.
  • the selectivity characteristic is made better than in any conventional types.
  • the double-tuned intermediate-frequency transformer according to the present invention may be said to have great value in practical use as described above.
  • a double-tuned intermediate-frequency transformer comprising a plurality of single-tuned intennediate-frequency transformers disposed adjacent to each other, each of said single-tuned intermediate-frequency transformers comprising, in combination: a winding portion having a center hole therein disposed at the center of the upper surface of a terminal plate, a coil wound on the outer periphery of said winding portion, a core supporter having a cap type core provided with a center core securely fixed to the upper portion thereof threadedly fitted into said center hole; a single shielding case covering said plurality of single-tuned intermediate-frequency transformers; wherein the degree of magnetic coupling via the air gap between the respective coils of said plurality of single-tuned intennediate-frequency transformers is freely adjustable by the suitable selection of the length of a sleeve portion of said cap type core relative to the length of said center core, respectively, thereof.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Coils Or Transformers For Communication (AREA)
US815915A 1968-04-18 1969-04-14 Double-tuned intermediate-frequency transformer Expired - Lifetime US3593245A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP3263168 1968-04-18

Publications (1)

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US3593245A true US3593245A (en) 1971-07-13

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US815915A Expired - Lifetime US3593245A (en) 1968-04-18 1969-04-14 Double-tuned intermediate-frequency transformer

Country Status (4)

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US (1) US3593245A (de)
DE (1) DE1919808B2 (de)
FR (1) FR2006414A1 (de)
GB (1) GB1236687A (de)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1984001853A1 (en) * 1982-11-05 1984-05-10 Spang Ind Inc Tunable-inductance magnetically-soft ferrite core structures and methods of manufacture
US4999743A (en) * 1989-09-27 1991-03-12 At&T Bell Laboratories Transformer with included current sensing element
US5432493A (en) * 1993-03-05 1995-07-11 Lucas Industries Public Limited Company Two linear differential transformers with armature

Citations (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1634923A (en) * 1924-07-15 1927-07-05 J C Thullen Transformer
US1978600A (en) * 1933-07-08 1934-10-30 Johnson Lab Inc Permeability-tuned resonant circuit
US2318415A (en) * 1939-07-31 1943-05-04 Gen Electric High-frequency iron core
US2388295A (en) * 1943-07-02 1945-11-06 Gen Electric Mutual coupling
GB580782A (en) * 1943-07-21 1946-09-19 British Thomson Houston Co Ltd Improvements in radio frequency transformers
US2435630A (en) * 1945-06-02 1948-02-10 Automatic Mfg Corp Tuned transformer assembly
US2438770A (en) * 1943-06-05 1948-03-30 Gen Electric Adjustable mutual coupling
US2483919A (en) * 1948-05-29 1949-10-04 Automatic Mfg Corp Coil and condenser assembly
GB744234A (en) * 1950-12-16 1956-02-01 Kurt Kaschke Dust-core for the coils of electrical communication circuits
US2823359A (en) * 1954-06-01 1958-02-11 Rca Corp Miniature intermediate-frequency transformer
US2837726A (en) * 1953-07-01 1958-06-03 Pearlman William Reluctance tuned radio frequency coil
US3155895A (en) * 1960-04-20 1964-11-03 Adams Electronics Inc Coil assembly with threaded stem core

Patent Citations (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1634923A (en) * 1924-07-15 1927-07-05 J C Thullen Transformer
US1978600A (en) * 1933-07-08 1934-10-30 Johnson Lab Inc Permeability-tuned resonant circuit
US2318415A (en) * 1939-07-31 1943-05-04 Gen Electric High-frequency iron core
US2438770A (en) * 1943-06-05 1948-03-30 Gen Electric Adjustable mutual coupling
US2388295A (en) * 1943-07-02 1945-11-06 Gen Electric Mutual coupling
GB580782A (en) * 1943-07-21 1946-09-19 British Thomson Houston Co Ltd Improvements in radio frequency transformers
US2435630A (en) * 1945-06-02 1948-02-10 Automatic Mfg Corp Tuned transformer assembly
US2483919A (en) * 1948-05-29 1949-10-04 Automatic Mfg Corp Coil and condenser assembly
GB744234A (en) * 1950-12-16 1956-02-01 Kurt Kaschke Dust-core for the coils of electrical communication circuits
US2837726A (en) * 1953-07-01 1958-06-03 Pearlman William Reluctance tuned radio frequency coil
US2823359A (en) * 1954-06-01 1958-02-11 Rca Corp Miniature intermediate-frequency transformer
US3155895A (en) * 1960-04-20 1964-11-03 Adams Electronics Inc Coil assembly with threaded stem core

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1984001853A1 (en) * 1982-11-05 1984-05-10 Spang Ind Inc Tunable-inductance magnetically-soft ferrite core structures and methods of manufacture
US4558295A (en) * 1982-11-05 1985-12-10 Spang & Company Tunable-inductance magnetically-soft ferrite core structures
US4999743A (en) * 1989-09-27 1991-03-12 At&T Bell Laboratories Transformer with included current sensing element
US5432493A (en) * 1993-03-05 1995-07-11 Lucas Industries Public Limited Company Two linear differential transformers with armature

Also Published As

Publication number Publication date
GB1236687A (en) 1971-06-23
DE1919808B2 (de) 1971-10-14
FR2006414A1 (de) 1969-12-26
DE1919808A1 (de) 1969-10-23

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