US1938631A - Transmitter - Google Patents

Transmitter Download PDF

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Publication number
US1938631A
US1938631A US520587A US52058731A US1938631A US 1938631 A US1938631 A US 1938631A US 520587 A US520587 A US 520587A US 52058731 A US52058731 A US 52058731A US 1938631 A US1938631 A US 1938631A
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US
United States
Prior art keywords
oscillator
resistance
key
anode
amplifiers
Prior art date
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Expired - Lifetime
Application number
US520587A
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English (en)
Inventor
Lunnon Frederick Charles
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RCA Corp
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RCA Corp
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Filing date
Publication date
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Application granted granted Critical
Publication of US1938631A publication Critical patent/US1938631A/en
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/02—Amplitude-modulated carrier systems, e.g. using on-off keying; Single sideband or vestigial sideband modulation
    • H04L27/04—Modulator circuits; Transmitter circuits

Definitions

  • This invention relates to keying arrangements for use in high frequency circuits. More particularly the invention relates to keying arrangements of the so-called absorber type, i.e. to ar- 6 rangements in which a transmitter, which is keyed, is kept under load during spacing periods by means of one or more thermionic tubes which are arranged to provide a load upon the source of anode potential when the transmitter is set to spacing.
  • absorber type i.e. to ar- 6 rangements in which a transmitter, which is keyed, is kept under load during spacing periods by means of one or more thermionic tubes which are arranged to provide a load upon the source of anode potential when the transmitter is set to spacing.
  • so-called absorber keying is effected by utilizing as an absorber tube during spacing periods a tube which during marking periods functions as an amplifier.
  • 0 represents an oscillator tube whose output circuit includes the usual fundamental oscillating circuit and is coupled through the customary coupling condenser to a first amplifier tube V1.
  • the coupling condenser is indicated at k1.
  • the grid circuit of the tube V1 contains a resistance R1 in series with a blocking condenser Blcl'.
  • the output circuit of the tube V1 contains the usual neutralized tuned circuit and is coupled to a second amplifier tube V2 which is in turn coupled to a third amplifier tube V3.
  • the circuit arrangement of the tubes V1, V2, V3 is similar, like parts being indicated in the drawing by like reference numerals provided with suflixes appropriate to the number of the stage concerned.
  • X1, X2 and X3 represent series resistances which may, if desired, be provided for reducing the amplitudes of the potentials applied from the source B to the anodes of the earlier stages. It is, of course, not necessary that there be a common anode source nor is the provision of resistances X1, X2, X3 an essential.
  • the negative terminal of-the source of anode potential is connected through a resistance Z to the common cathode connection and a key K shunted by a 'co'ndenser'as shown is connected across the said resistance Z.
  • the grid. circuits of the amplifier tubes are completed as shown to tapping points P1, P2 and P3.
  • the adjacent terminals of the devices R1 and 3701, R2. and Bk2, R3 and Bk3 are connected to the points P1, P2 and P3 respectively of the resistance-Z.
  • the grid circuit of the oscillator 0 contains a resistance R0 and a capacity BkO arranged in similar'manner to the corresponding parts of the amplifiers, the grid circuit of the said oscillator being connected to a tapping point P0 on resistance Z.
  • the anode currents of the stages will fiow through the resistance Z and the various grids will therefore be biased negatively by virtue of the voltage drop in the said resistance Z, the amounts of negative bias depending on the current fiow, the value of Z, and the positions of the various tapping points.
  • the arrangement may be such that when the key is open the negative bias applied to the grid of the oscillator 0 is sufiicient to stop oscillations with the result that the driving voltage is removed from the grids of all the subsequent stages.
  • the arrangement is such that when the key is open the negative bias applied to the grid of one of the intermediate stages is suflicient to reduce the input of that stage to zero thus removing the driving voltage from subsequent stages, whilst leaving the master oscillator and the previous stages (if any) functioning. It will be observed however thatin both stage arrangements anode current continues to flow in the stages subsequent to that at which the negative grid bias is applied and the power represented by this current at the effective anode potential is of course dissipated in the tubes in question.
  • the amount of this dead loss anode current in each stage is controlled by the negative grid bias derived from the resistance Z which is in turn determined by the value of the said resistance and the position of the appropriate tapping points. For best results these variables should be so adjusted that the power dissipated in the tubes of each stage is as great as can be permitted. In general the power which may be allowed 95 to be taken by each stage when the key is open will be about 25% of thattaken when the key is closed. The output from the source of anode potential B will therefore alternate during keying from full load to about 25% of full load. It will therefore be observed that during keying there is no discontinuity or interruption from the source B so that the transit time of the key need not be considered.
  • a substantial advantage of the invention lies in the fact that the only additional apparatus required for effecting absorber keying is the resistance Z and (of course) the key.
  • the negative terminals of all the sources shall be connected together and then through the common resistance Z to the common cathode connection.
  • a method of predetermining the value of the resistance Z so that the valve in each stage subsequent to the one that is cut off will set itself at that point in its characteristicat which'it dis sipates as absorber its maximum permissible anode loss will be understood from the following example.
  • the.'oscillator stage 0 is that which is to be out Oh when the key is opened, i. e. the driving voltage is to be'r'emoved from the grids of the subsequent stages Vl, V2, V3.
  • the permissible anode loss in the stage V1, V2, V3 be respectively 111, v2, 123 watts. lithe anode potential'be VBthen for the stage V1 the current whichcan be allowed to flow during spacing periods is Q.
  • the grids of the two subsequent stages should be tappedon to Z at points such that the ratio of the resistance between the tapping point in questionand the common cathode connection to the whole resistance will be in the case of the second amplifier ie 8 and in the case of the third amplifier.
  • the grid of the master oscillator should be tapped on to the resistance Z at such a point that the negative potential between that point and the common cathode connection when the amplicoupled to said oscillator, an impedance included in'a portion'of a circuit which is common to the anode circuits of said oscillator and said amplifiers, means for deriving bias potential for said oscillator and said amplifiers from voltage drop occurring in said impedance and keying means in shunt with said impedance, the v impedance being such thatin one position of the keying means the bias applied to'the oscillator is sufficient to stop oscillation so that the driving voltage is removed from the input electrodes of 2.
  • Signaling means comprising a thermionic oscillator, aplurality of thermionic amplifiers coupled in cascade and to said oscillator, an imioo pedance included in a portion of V a circuit which is common to the anode circuits of said oscillator and said amplifiers, means for deriving bias potential for said oscillator and said amplifiers from voltage drop occurring in said impedance, and keying means in shunt with said impedance, the impedance being of such a value that in one position of the keying means the bias applied to one ofv the initial amplifiers coupled to said oscillator is brought to avalue to render said amplifier inoperative whereby driving voltage is removed from subsequent amplifiers.
  • a signaling arrangement comprising atherrnionic tube oscillator, a plurality of cascade connected thermioniotube amplifiers coupled to said oscillator, anode circuits for said oscillator and amplifiers, said anode circuits having a common portion, a resistance included in said com- ,mon portion, connections tapped to said resistance, said connections being connected to the lator and amplifiers, and a key in parallel with said resistance.
  • a transmitter arrangement comprising an oscillation generator including, a thermionic. .tube, a plurality of thermionic tubes connected therewith, energizing circuits connected between the output electrodes of the tube in said oscillation generator and the output electrodes of each of said second mentioned tubes, said energizing circuits having a portion in common, an impedance common to said energizing circuits, a key connected in shunt to said impedance, and connections between the control electrodes of said tubes and points on said impedance, such as to cause'said oscillator. to develop oscillations and said tubes to act as amplifiers of the oscillations generated by said generator when said key is closed and to bias said oscillator to cut-off while permitting said amplifiers to draw a predetermined amount of energy from said source when said key is open.
  • modulating means connected with said impedance for varying or modulating the amount of energy flowing in said impedance at signal frequency, thereby varying the amount of oscillating en-

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Amplifiers (AREA)
  • Microwave Amplifiers (AREA)
US520587A 1930-03-20 1931-03-06 Transmitter Expired - Lifetime US1938631A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB8988/30A GB351051A (en) 1930-03-20 1930-03-20 Improvements in or relating to keying arrangements for use in high frequency circuits

Publications (1)

Publication Number Publication Date
US1938631A true US1938631A (en) 1933-12-12

Family

ID=9863189

Family Applications (1)

Application Number Title Priority Date Filing Date
US520587A Expired - Lifetime US1938631A (en) 1930-03-20 1931-03-06 Transmitter

Country Status (5)

Country Link
US (1) US1938631A (en(2012))
BE (1) BE378336A (en(2012))
DE (2) DE538841C (en(2012))
FR (1) FR708795A (en(2012))
GB (1) GB351051A (en(2012))

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE755785C (de) * 1933-03-16 1952-03-31 Marconi Wireless Telegraph Co Anordnung zur automatischen Einschaltung eines Senders mit Hilfe von gleichgerichteten Modulationsschwingungen

Also Published As

Publication number Publication date
DE538841C (de) 1931-11-17
BE378336A (en(2012)) 1931-04-30
GB351051A (en) 1931-06-22
DE590808C (de) 1934-01-11
FR708795A (fr) 1931-07-28

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