US2226694A - Neutralization circuit for short wave transmitters - Google Patents

Neutralization circuit for short wave transmitters Download PDF

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Publication number
US2226694A
US2226694A US188233A US18823338A US2226694A US 2226694 A US2226694 A US 2226694A US 188233 A US188233 A US 188233A US 18823338 A US18823338 A US 18823338A US 2226694 A US2226694 A US 2226694A
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circuit
voltage
input
electrodes
output
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Expired - Lifetime
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US188233A
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English (en)
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Buschbeck Werner
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Telefunken AG
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Telefunken AG
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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F1/00—Details of amplifiers with only discharge tubes, only semiconductor devices or only unspecified devices as amplifying elements
    • H03F1/08—Modifications of amplifiers to reduce detrimental influences of internal impedances of amplifying elements
    • H03F1/14—Modifications of amplifiers to reduce detrimental influences of internal impedances of amplifying elements by use of neutralising means
    • H03F1/16—Modifications of amplifiers to reduce detrimental influences of internal impedances of amplifying elements by use of neutralising means in discharge-tube amplifiers

Definitions

  • the invention relates to a neutralizing circuit for short waves in which essential drawbacks of the hitherto known circuits are overcome.
  • Figs. and 6 represent two well known neutralizing circuit arrangements of the prior art.
  • a balance may be readily achieved between tube capacity Cag and neutralizing capacity Cn, such that a voltage introduced in the input does not result in developing a voltage across the output.
  • voltage across the output circuit sets up a potential difierence between grid and cathode by way of the voltage dividing capacity path Cag, C1. back through the neutralizing condenser Cn because the balance before mentioned assures that no current fiows in the input coil system as a result of voltage across the output circuit, and therefore there is no way for current through the neutralizing condenser to influence the potential difference between grid and cathode.
  • Fig. 5 is sometimes rearranged so that thecathode of the amplifier is connected to the center of the input coil system rather than to the center of the capacity branch thereacross.
  • the same phenomenon occurs except that the amount of voltage fed back is reduced in proportion to the coefiicient of coupling between the two halves of the input coil, and the phase of the feed back becomes regenerative due to the re versal of the sign of the reactance between grid and cathode.
  • Fig. 6 a similar known neutralizing arrangement demonstrates that while a perfect bridge balance will prevent any coupling between input and output circuits, except by, virtue of the desired relay action of the tube, the voltage impressed upon the input circuit will produce a voltage between anode and cathode and vice versa. This again is true whether the cathode be connected to an intermediate point on the capacitive branch of the output circuit or tea corresponding intermediate point on the inductive branch thereof.
  • Figs. 1 and 2 illustrate two ways of eliminating feed-back in the grid neutralizing circuit in accordance with the invention
  • Figs. 3 and 4 illustrate two ways of eliminating feed-back in the anode neutralizing circuit in accordance with the invention.
  • Figs. 5 and 6 represent well known circuit arrangements shown for the purpose of the above exposition.
  • Fig. 1 shows a grid neutralizing circuit comprising the tube R, the grid-anode capacity GAG, the neutralizing capacity Cu and the capacities C1 and C2 of the oscillatory circuit.
  • Item G represents the grid point
  • K is the cathode point
  • A designates the anode point
  • N the neutral point.
  • the oscillatory input circuit lies between N and G.
  • a T element is placed in parallel to this circuit, said T member consisting of the two inductances L and a capacity C.
  • the inductances L may serve at the same time as the coil of the oscillatory circuit. Without the condenser C a reactive coupling potential would exist at the grid point G which is determined by the proportion of the capacities CAG- and 01.
  • the T element may consist either of two inductances and one capacity, as shown in Fig. 1, or it may consist of two capacities and one inductance, according to Fig. 2. In applying the invention, it is wholly immaterial whether the voltage division in the neutralizing bridge proper is capacitive or inductive.
  • the passing of energy from the control transmitter to the main transmitter can be eliminated in the anode neutralizing circuit while the circuit need not be further developed into a push-pull double bridge as Was hitherto the case.
  • the T element lies, as shown in Fig. 3, between the points A, N, and K.
  • Fig. 3 there is represented for the sake of clearness the bridge arrangement for the entire circuit, whereby R is again the tube, C1 and C2 the voltage divider capacities and A, N, K the anode point, neutral point and cathode point respectively.
  • the control transmitter is inserted and between A and N the main transmitter.
  • the anodecathode path is short circuited as viewed from the control transmitter.
  • FIG. 4 shows another mode of embodiment of Fig. 3 which corresponds to Fig. 1. It should, moreover, be emphasized that the efiectiveness of the arrangement described is not limited to rigorously exact series resonance tuning of the T element and that anywhere in the proximity of resonance an essential improvement over the hitherto known circuits is obtained.
  • the resultant impedance X of a series element having the resonance resistance X0 increases at first gradually as the actual frequency w departs from the resonant frequency 200, in accordance with the equation For obtaining substantially all the results of the invention, it is only necessary that this value remain lower than the reactance XAG of the gridanode capacity.
  • the conditions are not quite as simple if the cathode, or anode, or both electrodes are not directly accessible, which in the case of ultra short waves is mostly the case owing to the electrode lead-ins.
  • the resistance value of the T member at anode neutralization, must no longer be zero, but it must be so apportioned that the voltage produced directly at the anode-cathode path by the exciting alternating voltage disappears.
  • the determination of the required resistance of the T element depends on the type of the circuit and after all on the type of the tube employed.
  • the invention can be applied in almost all bridge neutralizing circuits in which, at exact balance, a counter coupling or feed back occurs between an input or output circuit and a pair of tube electrodes.
  • an amplifier circuit having a vacuum tube having input and outputelectrodes, an output circuit connected to said output electrodes, and an input circuit for energizing said input electrodes
  • the method of eliminating feed-back of voltage from said output circuit to said input electrodes due to inherent interelectrode capacity which includes as a first step neutralizing voltage across said input circuit due to voltage across said output circuit, and as a second step utilizing series resonance to eliminate residual voltage between input electrodes due to potential difference existing across the portion of said input circuit to which said'input electrodes are connected.
  • an amplifier circuit having a vacuum tube having input and output electrodes, an output circuit connected to said output electrodes, and an input circuit for energizing said input electrodes
  • the method of eliminating transfer of voltage from said input circuit to said output electrodes due to inherent interelectrode capacity which includes as a. first step neutralizing voltage across said input circuit due to voltage across said output circuit, and as a second step utilizing resonance efiects to eliminate residual voltage between output electrodes due to potential difierence existing across the portion of said output circuit to which said output electrodes are connected.
  • the method of eliminating transfer of voltage from said input circuit to said output electrodes due to inherent interelectrode capacity which includes as a first step neutralizing voltage across said input circuit due to voltage across said output circuit, and as a second step utilizing series resonance to eliminate residual voltage between output electrodes due to potential diiTerence existing across the portion of said output circuit to which said output electrodes are connected.
  • an amplifier circuit having a vacuum tube having first and second sets of electrodes, an output circuit connected to said second electrodes and an input circuit for energizing said first electrodes
  • the method of eliminating transfer of voltage from one of said circuits to that set of electrodes to which it is not directly connected due to inherent interelectrode capacity which includes as a first step neutralizing voltage across said input circuit due tovoltage across said output circuit, and as a second step utilizing resonance efiects to eliminate residual voltage between the electrodes of said one set due to potential difierence existing across the portion of the circuit to which said one set of electrodes is connected.
  • an amplifier circuit having a vacuum tube having first and second sets of electrodes, an output circuit connected to said second electrodes and an input circuit for energizing said first electrodes
  • the method of eliminating transfer of voltage from one of said circuits to that set of electrodes to which it is not directly connected due to inherent interelectrode capacity which includes as a first step neutralizing voltage across said input circuit due to voltage across said output circuit, and as a second step utilizing series resonance to eliminate residual voltage between the electrodes of said one set due to potential difierence existing across the portion of the circuit to which said one set of electrodes is connected.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Particle Accelerators (AREA)
US188233A 1937-03-05 1938-02-02 Neutralization circuit for short wave transmitters Expired - Lifetime US2226694A (en)

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DE2226694X 1937-03-05

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US (1) US2226694A (en(2012))
FR (1) FR834462A (en(2012))
NL (1) NL53699C (en(2012))

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2663766A (en) * 1950-06-28 1953-12-22 Bell Telephone Labor Inc Transistor amplifier with conjugate input and output circuits
US2818472A (en) * 1955-02-18 1957-12-31 Standard Coil Prod Co Inc Neutralized triode tuner
US2841655A (en) * 1956-12-06 1958-07-01 Rca Corp Stabilized high frequency amplifier circuits
US2843683A (en) * 1956-10-26 1958-07-15 Sarkes Tarzian Television tuner input circuit
US2843828A (en) * 1951-10-18 1958-07-15 Avco Mfg Corp Ultra-high-frequency converter for very-high-frequency television receiver
US2949580A (en) * 1956-07-27 1960-08-16 Standard Coil Prod Co Inc Neutralizing circuits

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2663766A (en) * 1950-06-28 1953-12-22 Bell Telephone Labor Inc Transistor amplifier with conjugate input and output circuits
US2843828A (en) * 1951-10-18 1958-07-15 Avco Mfg Corp Ultra-high-frequency converter for very-high-frequency television receiver
US2818472A (en) * 1955-02-18 1957-12-31 Standard Coil Prod Co Inc Neutralized triode tuner
US2949580A (en) * 1956-07-27 1960-08-16 Standard Coil Prod Co Inc Neutralizing circuits
US2843683A (en) * 1956-10-26 1958-07-15 Sarkes Tarzian Television tuner input circuit
US2841655A (en) * 1956-12-06 1958-07-01 Rca Corp Stabilized high frequency amplifier circuits

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Publication number Publication date
FR834462A (fr) 1938-11-22
NL53699C (en(2012))

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