US1831640A - Tuned radio frequency coupling device - Google Patents

Tuned radio frequency coupling device Download PDF

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Publication number
US1831640A
US1831640A US253831A US25383128A US1831640A US 1831640 A US1831640 A US 1831640A US 253831 A US253831 A US 253831A US 25383128 A US25383128 A US 25383128A US 1831640 A US1831640 A US 1831640A
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United States
Prior art keywords
coupling
frequency
circuit
reactances
series
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Expired - Lifetime
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US253831A
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English (en)
Inventor
Walter Van B Roberts
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RCA Corp
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RCA Corp
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Publication date
Priority to BE358135D priority Critical patent/BE358135A/xx
Application filed by RCA Corp filed Critical RCA Corp
Priority to US253831A priority patent/US1831640A/en
Application granted granted Critical
Publication of US1831640A publication Critical patent/US1831640A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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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
    • H03H7/0138—Electrical filters or coupling circuits
    • H03H7/0146—Coupling circuits between two tubes, not otherwise provided for

Definitions

  • Another object of the invention is obtaining of uniformselectivity throughout the broadcasting range.
  • Still another object of the invention is to obtain uniform amplification throughout the broadcast range.
  • Fig. 1 shows a preferred embodiment 'of the invention
  • Fig. 2 illustrates a modification of them vention slightly differing in detail from Fig. 1;
  • Fig. 3 is similar to Fig. 1 except that the arrangement thereindisclosed allows forJthe.
  • Fig. shows' a'circuit incorporatingthe i11- vention broken up into its constituent parts;
  • Fig. 5a shows the coupling circuit of Fig. 1 detached and;
  • Fig. 5b shows'curves for certain conditions existing in the circuit of Fig. 5a. 1
  • this invention deals with the design of a constant coupling circuit for vacuum tubes arranged in cascade relation.
  • circuits known inthe art, when producing approximately constant couplingfor a certainrange of frequencies. circuits have been designed in whichthe coupling between the tubes is the sum of an inductive and a capacitive coupling. The purpose of this dual coupling effect is that'upon a change infrequency-the lossin the coupling value of the capacitive coupling would be made up by the increase in inductive coupling, or vice versa,
  • the-oldsystem utilizes the constancy of a sum of two quantities onegoing up as the other goes down, while the present invention utilizes theconstancy obt'ainablein a'rajtio of two quantities which vary propor tionately.
  • Fig. 1 two thermionic tubes 1 and 20f a cascadecirc'uit are-shown coupled-together by circuit 3, consisting of the inductances Li an'dL and the capacity C all ofwhich. are preferably units of fixed value, Anextremity-of each inductance is connected to the filament circuit and-the. op; posite extremities are connected to the opposite terminals of'the capacity C.
  • the plate battery B may be connected to energize the: plate inany suitable manner for example in series with the coil L as shown.
  • Coupling circuit. 3 is tuned to a frequency outside the rings, inthis case, lower than any frequency to be received by-properly selecting the values of units C, L and L.
  • a series resonant circuit consisting of condenser 5 and inductance 6 is connected in parallel with inductance L Either or both of the elements 5, 6 may be made adjustable for tuning.
  • Fig.2 shows a different method of coupling in which 3 as before represents the coupling circuit composed of the fixed condensers (3 and C and the fixed inductance L.
  • This modification replaces the inductances of the coupling circuit of Fig. 1 by capacities and the capacity by an inductance.
  • Fig. 2 because of the arrangement a direct current path must be provided in the plate filament circuit which path is shown by choke coil 4; and battery B.
  • the coupling device is tuned by meansof C L and C to a frequency above any to be re ceived.
  • Mutual inductance between the various coils in Figs. 1 and 2 is not necessary, but may be present without detriment if not excessive.
  • Fig. 3 which is similar to Fig. 1, except that the tuning inductance 6 in the variable condenser 5 have been transposed.
  • the inductance 6 has been shown variable as it would be preferable to do at least part of the tuning by varying the inductance, or otherwise the tuning range might not be sufficient and the voltage amplification might become relatively too large at the high frequency end of the scale. However, if necessary the tuning may be done entirely by either variable inductances or variable'condensers.
  • Fig. 4 in which a circuit according to the invention is broken up into its fundamental constituent parts.
  • the plate circuit of the tube 1 is energized in themanner shown in Fig. 2 and a blocking condenser 7 of large capacity is utilized to prevent short circuit through inductance L
  • the input circuit of tube 2 is provided with a grid leak 8 and grid condenser 9 for enabling the tube to act as a detector in a well-known manner.
  • the input vacuum tube 1 acts as if it were an alternating current generator having definite internal resistance.
  • a so-called transducer or coupling circuit 3 made up of inductances L and L and capacity C.
  • transducer is usedto designate any network of impedances which receives energy in one pair of terminals and delivers it usually at a different voltage out of another pair of terminals.
  • the output terminals of the transducer are connected to the series combination inductance 6 and capacity 5. This series combination is utilizedfor the purpose of producing high voltage by passage of the current through large reactances and to select or tune by insuring that there is only one frequency at which this resonance voltage occurs.
  • the last fundamental constituent is the input circuit of the next vacuum tube 2 which may be connected across any two points through Z and Z and the other component through Z will be say, 2' and the part through Z be 71 From well-known formulae The part going through Z Z will Let us designate by the word transducance the voltage appearing between the output terminals per ampere flowing into the input, the output terminals being supposedly unconnected to anything.
  • the uniformity of selectivity and amplification depends very approximately upon the transducance.
  • the desired result is to have the same current flowing through the tuning elements at'all frequencies and further suppose that the resistance of the tuning ele ments does not vary with frequency. Then, the so-called tra-nsducance should remain constant in order to receive the desired retasters sult. If other results are desired, the transducance should vary with frequencies in a definite fashion.
  • the expression for the transducance takes the form of a ratio such as shown above by Equation and that by suitable choice of constants the numerator and denominator can be made to vary almost proportionately over the desired frequency range such as 50 to 150 kcs. so that the transducance remains substantially constant over the range.
  • a condition would approximately exist for the frequencies shown be-- tween the points a and b of Fig. 56. It will be seen from that portion of the two curves that the values increase almost proportionately which means that the transducance will remain approximately equal for that range.
  • a thermionic valve having input and output circuits said output circuit comprising a choke coil, a current source in series therewith and a capacity across said choke coil and said source, a second thermionic valve having input'and output circuits, said input circuit comprising a pair of condensers in series and an inductance in parallel therewith, and means for connecting one of said last named condensers to said first mentioned condenser comprising a circuit including an inductance.
  • an amplifier system for amplifying electrical impulses of radio frequency, the frequency of which may vary within specified limits, a source of radio frequency energy, a space discharge device having input and output circuits, a transducer for coupling said source and said space discharge device and maintaining a constant coupling relationship therebetween irrespective of whichever frequency within said limits is being transferred therethrough, said transducer having an input side and an output side said output side being connected to a series combination of inductance and capacitance at least one of which is adjustable for tuning said series combination to any frequency within said specified limits, the input of said space discharge device being connected across two points of said series combination having a difference of potential between them, said transducer comprising two reactances of like sign and one reactance of opposite sign connected in series, said reactances of like sign and said reactance of unlike sign beingtuned in combination to'a'frequency outside said specified limits, said output slde of, the transducer being formed across two pointsof one of said first mentioned likereactances, and said inputside being formed across two points of the
  • a system for coupling a source of alternating current to the input of a space discharge device adapted to maintain constant coupling irrespective of the frequency transferred therethrough within a frequency band to be received which comprises a pair of terminals for input energy an inductive reactance connected in shunt, a capacitive reactance in series, another inductive reactance in shunt and a series pair of reactances of opposite signs, one thereof being adjustable,
  • said first three named reactances being chosen to have the sum of their reactances vanish at a frequency below the range of frequencies to be received.
  • a system for coupling a source of alternating current to the input of a space discharge device adapted to maintain constant coupling irrespective of the frequency within a frequency band to be received transferred therethrough which comprises a pair of input terminals, a capacitive reactance connected in shunt, an inductive reactance in series, another capacitive reactance in shunt and a series pair of reactances of opposite signs, one thereof being adjustable, in shunt with said second capacitive reactance, the input electrodes of said space discharge device being tapped across one of said series pair of reactances, said first three named reactances being so proportioned that the sum of their reactances vanish at a frequency abovethe range of frequencies to be received.

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US253831A 1928-02-13 1928-02-13 Tuned radio frequency coupling device Expired - Lifetime US1831640A (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
BE358135D BE358135A (enrdf_load_stackoverflow) 1928-02-13
US253831A US1831640A (en) 1928-02-13 1928-02-13 Tuned radio frequency coupling device

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US253831A US1831640A (en) 1928-02-13 1928-02-13 Tuned radio frequency coupling device

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US1831640A true US1831640A (en) 1931-11-10

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US253831A Expired - Lifetime US1831640A (en) 1928-02-13 1928-02-13 Tuned radio frequency coupling device

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BE (1) BE358135A (enrdf_load_stackoverflow)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2688086A (en) * 1948-07-10 1954-08-31 Motorola Inc Television tuner
US2724055A (en) * 1945-09-17 1955-11-15 Bliss William Roderic Coupling system for high frequencies
US2756391A (en) * 1956-07-24 Voltage-responsive electrical
US4164710A (en) * 1976-03-05 1979-08-14 Sanyo Electric Co., Ltd. Very high frequency tuner for eliminating image interference and stray capacitance effects

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2756391A (en) * 1956-07-24 Voltage-responsive electrical
US2724055A (en) * 1945-09-17 1955-11-15 Bliss William Roderic Coupling system for high frequencies
US2688086A (en) * 1948-07-10 1954-08-31 Motorola Inc Television tuner
US4164710A (en) * 1976-03-05 1979-08-14 Sanyo Electric Co., Ltd. Very high frequency tuner for eliminating image interference and stray capacitance effects

Also Published As

Publication number Publication date
BE358135A (enrdf_load_stackoverflow)

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