Патент USA US2123727код для вставки
July 12, 1938.‘ H. E. HOLLMANN 21,123,727 MODULATION CIRCUIT FOR RETARDING FIELD GENERATORS Filed Oct. 25, 1934 MON/LA T/OA/ P075'N T/ALS MODULATION ' POTENTIALS INVENTOR HANS ERICH' HOLLMANN ATTO R N EY Patented July 12, 1938 ' UNITED STATES PATENT OFFICE 2,123,727 MODULATION CIRCUIT FOR RETARDING FIELD GENERATORS ’ Hans Erich Hollmann, Berlin, Germany, assignor to Telefunken Gesellschaft fiir Drahtlose Tclc- ' graphie m. b. H., Berlin, Germany, a corpora tion of Germany Application October 23, 1934, Serial No. 749,535 In Germany November 3, 1933 5 Claims. (c1..179_171); It is known, in the prior art, that a generator connected in av Barkhausen-Kurz type of retarding-?eld circuit arrangement is modulable with relatively low alternating voltages and that the 5 modulator potential em is superposed upon the retarding electrode potential Eb. While this method notes the retarding ?eld tube which excites a Lecher wire ‘system L united with the grid and the anode in well-known manner. M denotes the modulation transformer whose winding S1, as above pointed out, is included in the lead brought 5 to the retarding ?eld electrode so that a- pure insures satisfactory modulation, it nevertheless alternating voltage em becomes superposed upon involves the drawback thatthe modulating volt- the biasing voltage Eb of the retarding ?eld elec age works, upon the internal retarding resistance trode.. In order that the modulation potential em, 10 0f the retarding ?eld generator; in other words, pursuant to the idea underlying this invention, 10 upon the resistance acting between the cathode may also be fed to the grid, a second secondary and the retarding ?eld electrode. Since the lat- winding S2 of the modulation transformer may be ter resistance amounts to- about 1000 ohms, this included in the grid lead. Transfer of current means a severe load for the source of the modula- 15 tion voltage which, in the majority of cases, consists of a transformer. In other words, although the voltages are inherently low, a considerable amount of modulation power must be provided. for the modulation frequency may then be equal ized and maintained constant by Virtue of the 15 mutual inductance of the two windings S1 and S2, without any action being brought upon the pri mary winding. This drawback is obviated entirely by the presAnother circuit scheme is shown in Fig. 3, in 20 ent invention. By the mere adoption of certain which the modulation potential em is imparted to 20 means and ways in the circuit organization, the grid by way of a suitable condenser C and is perfectly non-dissipative modulation of a retard- prevented from leaking or draining away to the ing ?eld generator is obtainable. The invention grid voltage source by the aid of the choke coil D is based upon the fact that the oscillator tube contained in the grid lead. In this circuit ar 25 of a retarding ?eld generator operates inside the rangement the transfer of current is equalized 25 saturation region, so that the total electron emis- between grid and retarding ?eld electrode by way sion current is=ig+ib, distributed over the re- of C, and for this reason the bridging condenser tarding ?eld electrode and the grid, is constant. must be chosen so large that it will still constitute Consequently, in the state of oscillation, the re- a short-circuit even for the lowest modulation 30 tarding ?eld characteristic ib=f (eb), having an inverted image pattern, is transferred to the grid end in the very same manner as in the static characteristics of the retading ?eld tube. For in- stance, Fig. 1 shows the two statically plotted 35 current characteristics of an oscillating retarding ?eld transmitter, it and 21, being observed as a function of the biasing retarding ?eld voltage eb. According to this invention, the modulator voltage cm is impressed not only upon the retarding 40 ?eld electrode, but, at the same time, also upon vthe grid. This means that operation takes place not only upon the retarding ?eld characteristic ib=f (6b), but, at the same time, also on the grid current characteristic ig=f (8b). In this case it 45 and ig become added, resulting in the constant saturation current is, and the modulation voltage em, as a consequence, works upon the pure satura- tion resistance of the tube. Fig. 1 shows curves explanatory of the comi0 ponent currents forming the total emission cur- frequency. Hence, in audio frequency modula- 30 tion a condenser of a few microfarads will be re quired, whereas for radio frequency modulation, say with one intermediate carrier frequency, the capacity of the turning bridge piece B will gen erally be sui?cient. In this instance, all that will 35 be necessary is the connection of the choke-coil D. What is claimed is: 1. An oscillation generator comprising an elec tron discharge device having an anode, cathode and a grid, means for supplying a positive po- 40 tential to said grid and a less positive potential to said anode relative to said cathode, whereby there is obtained pendulum motion of electrons about said grid, and means for supplying modu l-ating potentials co-phasally to said anode and 45 grid, the last said means comprising means for causing a constant saturation electron ?o-w from said cathode. 2. In a modulation circuit for a retarding ?eld type generator, an electron discharge tube hav- 50 rent. Figs. 2 and 3 show, schematically, two em- ing a cathode, an anode and a grid, means for bodiments of the invention. impressing a highly positive charge on said grid A circuit organization adapted to carry the basic idea of the invention into practice is illus5 trated in Fig. 2. Referring to the same, R de- ' relative to the charges on said cathode and said anode respectively, means for impressing simul taneously upon said grid and upon said anode, 55 2 2,123,727 respectively, modulation voltages which are co _ phasal and additive in their effect, and means for maintaining a constant saturation electron ?ow from said cathode. 3. An oscillation generator comprising an elec to said cathode, means for maintaining a rela tron discharge tube having a plate, a cathode and a grid, means for rendering the charge on tively small difference of direct current potential between the cathode and the retarding electrode, a transformer having a primary winding upon said grid highly positive with respect to said which modulation potentials may be impressed, cathode, means for maintaining a relatively small di?erence of direct current potential between the 10 cathode and the plate, means for producing a 15 5. An oscillation generator comprising an elec tron discharge tube having a cathode, a grid and a retarding electrode, means for maintaining a highly positive charge on said grid with respect constant saturation electron flow from said cath ode, and means for impressing modulation volt ages co-phasally upon said grid and upon said plate while facilitating the operation of the next previously mentioned means. 4. A generator in accordance with claim '3 and having electrostatic coupling means between the grid and the plate for the transfer of modulat ing potentials to said grid, said coupling means 20 having a low impedance to the band of fre quencies of said modulating potentials. and two secondary windings, one of said second 10 ary windings being in circuit between the oath ode and the grid and the other of said secondary windings being in circuit between the cathode and the retarding electrode, and a capacitor inter coupling the grid and the retarding electrode, 15 said transformer‘ in combination with said ca pacitor constituting means for maintaining a. constant amplitude of electronic emission from said cathode while impressing said modulation potentials co-phasally upon the electrodes of 20 said tube. HANS ERICH HOLLMANN.