US2189897A - Modulation system - Google Patents

Description

Feb. 13, 1940. F. GuTzMANN ET AL MODULATION SYSTEM Filed Jan. 12, 1958 Patented Feb.v 13, 19.40 l l UNITED STATES PATENT OFFICE MoDULA'rioN SYSTEM Fritz Gutzmann, Fichtenau, Kreis Niederbarnim, and Erich Schulze-Herringen, Berlin, Germany, assignors to C. Lorenz -Aktiengesellschaft, Berlin-Tempelhof, Germany, a company v Application January 12, 1938, Serial No. 184,646

In Germany January 13, 1937 3 Claims. (Cl. 179-1715) In order to save energy in the modulation4 of grid biasing circuit. To resistance 6 a continuous high frequency currents various methods have voltage, generated by a member 1, is conveyed, been devised. According to one of these methods this voltage fluctuating in accordance with the modulated high frequency is amplified to a high mean modulation rhythm, that is to say, in ac- 5 degree by means of an anode voltage whiclnis apcordance with the mean valueof the modulation 5 plied to the high frequency powerv amplifier-and amplitude. Member l in a well-known manner which is varying in accordance with the modulacomprises a rectifier arrangement and smoothing tion rhythm. This method is of merely theomeans in order to derive from the modulation retical value, not having been carried into effect Currents-the input Circuit f member .l iS likelo so far. y wise connected to the microphone 5-a continuous 1o In order to improve the efllciency of this method voltage which is fluctuating in accordance with the invention suggests to combine therewith the the mean value of the modulation amplitudes. weil-known method of the so-caued Hapugemodu Behind stage 2 high frequency amplifier tubes l lation, that is, a modulation which involves vari-v and 9 are arranged Tube 8' is merely in the f l ation of the carrier wave. In this way not only nature 0f en amplifier fOr the mOdulated Heliusthe energy conditions, but also the conditions of Centrolled high frequency Currents. Tube 9. operation are improved, as will appear from the hOWeVeI, iS t0 be a high frequency DOWer endl i following. stage.l The anode voltage is conducted to this As is weil-known, modulating methods are Stege over a 10W frequency transformer l0. The

generally required to effect a modulation without modulating Voltage iS superimposed 0n the anode 2o distortion. Theaforesaid method of applying@ voltage with the aid of a transformer. To such the high frequency power amplifier a continuous end microphone 5 iS COYlneeted t0 an amplifier ll anode voltage which is varying in the modulation which acts to influence the grid 0f a lowfrequency rhythm does not fulfil this requirement, but wiu Class B amplifier '2.0f the push-pull type. This z5 fulfil it to a certain degree if combined with the amplifier iS employed in Order to Provide fOl' the 25 Hapug-method. If, however, the modulation isV necessary great efllclency Wien Which the Inodu" desired to be extrem ly well qualified then accordloting Voltage le acting on the 'anode of tube 9 ing to a further feat re of the invention it is con- In accordance With another feature of tne lnvenient at the same time to effect at the grid of Venllon ampllnel l2 may contrarlly llo the no1' mol the high frequency power stage a counter coupling 'modulatlon amplifiers of the class B type operate 3 4of the low frequency alternating anode voltage, Without closed circuit conneotlon; il', S to be an additional modulation that might arise understood here that distortions may be allowed through anodal retroaction being avoided in this to al'lSe to soule extent Since they are compenway. If desired, the method using such counter Sal'eol by line Sold counter coupling coupling may be employed in conjunction with In order to avoid the aforesaid anodal retro- 35 the aforesaid modulating method even without acllon lne best course Wlll be lo dellve o counter the aid of the Hapug meth0d voltage from the output transformer of amplifier The invention will be understood from the fol-` l2 Wllin the ald of uiwlnding I3 and t0 convey lowing description, reference being had to the llhls Voltage '0o the glld of tube 9 Over 8 tranS-' 40 accompanying drawing which is a wiring diagram formel l- Iii 1S of course DOSSlble also to take 40 of one embodiment of the invention. In this this counter Voltage from other Suitable points. embodiment both the Hapug-method and the BY A' connections l0 lille @node battery, and counter-coupling method are employed. by .Gf conncclllons lo the grid-battery are de- Part I schematically represents the prestages noted' 45 of a transmitter, While part 2 is the modulating The here described arrangement entails a constage. The grid of part 2 is influenced by the siderable Saving in energy' as will appeal' from the followin st t ment: Th e method of grid voltagemodulation. To such end fom a pubu supy by a 10 kfsnrasnci:

e ll'ansformer 3 is include@ in the grid elm-:ult of provided with the hitherto knownk anode voltage part 2 and 1s located also 1n the output circuit of control (normal anode voltage modulation' not 50 a medulatien ampliei" 4. 5 indicates, a micro' the aforesaid amplifier for modulated high frephone. The same stage is influenced also by the quency energy) is with m=0 about 340 k. v1., displacement of the working point, that is,l the with m=0.3 about 360 k. w. and with m=1 about displacement peculiar to the Hapug-method. 520 k. w., m being the degree of modulation. In

For this purpose a resistance 6 is disposed in the the novel arrangement, however, with a re il mainder or at-rest value p=0.6 of the carrier the respective values are in the casc of m=0 about 240 k. W., m=0.3 about 300 k. W., m=1 about 450 k. w. Thus, as compared with the normal grid voltage modulation a saving of about 200 k. W. is afforded, while the saving over the anode voltage modulation is about 166 k. w.

In this connexion it may be mentioned that it is well-known per se to effect the Hapug-displacement of the working point .by inuencing the anode voltage of the nal stage. This meth- Y od, however, has the drawback that the anode voltage source must be worked upon directly, that is to say, in the case of the customary grid controlled rectiers the grid control must be so influenced as to displace the ignition point in accordance with the mean value of the modulation. Such influencing, however, can not be accomplished with a sufiicient quickness, this fact being due to an insufliciency of the means available in this regard. Apart from this, the modulating tube is by the invention better utilized than has been the case heretofore since as stated the class B amplifier' allows of admitting greater distortions.

What is claimed is:

1. A high frequency transmitter arrangement comprising a source for producing a high frequency carrier, means for modulating said high frequency carrier with a modulation voltage, means for fluctuating said high frequency carrier in dependency upon the mean value of said' modulation Voltage, a power amplifier, means for applying to said power amplifier the modulated and fluctuated high frequency carrier, and means for varying the anode direct current potential of said power amplifier dependent upon said modulation voltage.

2. A high frequency transmitter arrangement comprising a source for producing a high frequency carrier, means for modulating said high frequency carrier with a modulation voltage, means for fluctuating said high frequency carrier in dependency upon the mean value of said modulation voltage, a power amplifier, means for applying to said power amplier the modulated and fluctuated high frequency carrier, and means for varying the anode direct current potential of said power amplifier dependent upon said modulation voltage, said last mentioned means being a class B amplifier of the push-pull type.

3. A high frequency transmitter arrangement comprising a source for producing a high frequency carrier, means for modulating said high frequency carrier with a modulation voltage, means for fluctuating said high frequency carrier in dependency upon the mean value of said modulation Voltage, a power amplifier, means for applying to said power amplifier the modulated and fiuctuated high frequency carrier, means for varying the anode direct current potential of said power amplifier dependent upon said modulation voltage, and counter coupling means for conveying said modulation Voltage to the grid of said power amplifier.

FRITZ GUTZMANN. ERICH SCHULZE-HERRINGEN.

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