US2184382A - Radio and other high frequency telegraph transmitters - Google Patents

Radio and other high frequency telegraph transmitters Download PDF

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Publication number
US2184382A
US2184382A US139865A US13986537A US2184382A US 2184382 A US2184382 A US 2184382A US 139865 A US139865 A US 139865A US 13986537 A US13986537 A US 13986537A US 2184382 A US2184382 A US 2184382A
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US
United States
Prior art keywords
resistance
key
screen grid
high frequency
radio
Prior art date
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Expired - Lifetime
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US139865A
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English (en)
Inventor
George Douglas Frank
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RCA Corp
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RCA Corp
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Filing date
Publication date
Application filed by RCA Corp filed Critical RCA Corp
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Publication of US2184382A publication Critical patent/US2184382A/en
Anticipated expiration legal-status Critical
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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 radio and other high frequency telegraph transmitters and more particularly to telegraph transmitters of the kind wherein keying is effected by varying in dependonce upon the position of a key or relay (hereinafter termed simply a key) the potential upon a screen grid of a tetrode or other high frequency tube of the screen grid type.
  • the principal object of the present invention is to provide improved keying circuits of the kind referred to which shall be very simple and which, nevertheless, shall not present the defect above mentioned, i. e., which shall be such that the load upon the high tension supply source remains substantially constant irrespective of Whether the key contacts are open or closed.
  • a keying circuit arrangement of the kind referred to comprises a tetrode or other high frequency tube of the screen grid type having its screen grid connected to a point upon a potentiometer resistance included between the positive terminal of the high tension supply source for the tube and the cathode point thereof and the key contacts are connected between the cathode point and a point between the screen grid and said positive terminal said last mentioned point being so chosen that the sum total feed current taken from the high tension supply source remains the same, or nearly the same, whether the key contacts be open or closed.
  • l is a high frequency tetrode whose cathode point 2 (shown as constituted by the usual intermediate tap on a resistance 3 shunting the cathode 4) is grounded and Whose anode 5 is connected, as in the usual Way, through a choke 6 to the positive terminal 1 of a source (not shown) of high tension supply '5 whose negative terminal 8 is grounded.
  • the control grid circuit and the output anode circuit of the screen grid tube are as well known per so.
  • control grid 9 is connected to the cathode point 2 through a resistance ID, the high 10 frequency drive being applied through condenser ll, while the output coilv I2 is connected to the anode 5 through a condenser l3.
  • the screen grid 14 of the tube is connected to the positive terminal 1 through a resistance I5, and 5 is also connected to the cathode point 2 through a second resistance 16 which latter is preferably shunted by a by-pass condenser 11.
  • the key l8 or its equivalent e.
  • the said tapping point 19 is so chosen that the current which passes through the key contacts when closedi. e., when the tube is biassed to cut off-4s the same or nearly the same as the sum total of the anode current and screen grid current flowing when the key contacts are open.
  • the high tension supply source 35 between terminals 1, 8, was 2,000 volts; the resistance value (hereinafter termed R1) between the positive terminal 1 and the tapping point I! was 19,000 ohms; the resistance (hereinafter termed R2) between the tapping point 40 I9 and the screen grid 14 was 31,000 ohms; and the resistance (hereinafter termed R3) between the screen grid 14 and the cathode point 2 was 50,000 ohms.
  • the screen grid tube was of the type now commercially known under the trade 45 designation Marconi D. E. S. 1. With these values the anode feed was ma.
  • the screen grid feed was 30 ma. making a total feed of ma., the screen grid resistance being 12,500 ohms.
  • the anode and screen grid feed currents fell to zero but the total feed (through the key) remained at 90 ma. with a keying resistance of 5,500 ohms.
  • the total feed or load upon the high tension supply source was practically the same irrespective of the position of the key and as movements of the key from mark to space may, in practice, be regarded as substantially instantaneous, there are practically no voltage or current surges and the high tension supply source remains steady.
  • tapping point I9 is adjustable so that an accurate state of balance can easily be obtained by trial and error.
  • an electron discharge tube having an emission electrode and a plurality of auxiliary electrodes, means for causing wave energy to flow between said electrodes, and for interrupting the flow of the same and for utilizing a substantially constant amount of energy during said operations including a source of direct current potential connected at its positive terminal to one of said auxiliary electrodes and at its negative terminal to said emission electrode, a resistance in shunt to said source of direct current potential, a connection between a point on said resistance and another of said auxiliary electrodes, and a key movable between closed and open positions shunting a portion of said resistance the resistance of said potentiometer being distributed between said connections in such a manner that said auxiliary electrodes and resistance impose a substantially constant load on said source of direct current in all positions of said key.
  • an electron discharge tube having an emission element and a plurality of auxiliary electrodes, means for causing wave energy to flow between said electrodes, and means for interrupting the flow of the wave energy and for utilizing a substantially constant amount of energy during said operations, including a source of direct current potential having a positive point thereon connected to one of said auxiliary electrodes and a negative point thereon connected to said emission electrode, a resistance connected between said points, a connection between another of said auxiliary electrodes and a point on said resistance, and a key movable between closed and open positions shunting a portion of said resistance, the value of said resistance distributed between said connections being such that said auxiliary electrodes and resistance impose a substantially constant load on said source of':

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Amplifiers (AREA)
  • Electron Tubes For Measurement (AREA)
US139865A 1936-05-12 1937-04-30 Radio and other high frequency telegraph transmitters Expired - Lifetime US2184382A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB202376X 1936-05-12
GB90237X 1937-02-09

Publications (1)

Publication Number Publication Date
US2184382A true US2184382A (en) 1939-12-26

Family

ID=26242589

Family Applications (1)

Application Number Title Priority Date Filing Date
US139865A Expired - Lifetime US2184382A (en) 1936-05-12 1937-04-30 Radio and other high frequency telegraph transmitters

Country Status (4)

Country Link
US (1) US2184382A (fr)
CH (1) CH202376A (fr)
FR (1) FR821505A (fr)
GB (1) GB475105A (fr)

Also Published As

Publication number Publication date
CH202376A (fr) 1939-01-15
FR821505A (fr) 1937-12-07
GB475105A (en) 1937-11-12

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