US2033984A - Modulation scheme for barkhausenkurz generators - Google Patents

Description

G. B. HAGEN March 17, 1936.

MODULATION SCHEME FOR BARKHAUSEN-KURZ GENERATORS Filed Jan. 19, 1933 AA/TiA/AM INVENTOR- GERHARD B. HAGEN BY #Q 4 Y E N R m A Patented Mar. 17, 1936 UNITED STATES MODULATION SCHEME FOR BARKHAUSEN- KURZ GENERATORS Gerhard B. Hagen, Berlin, Germany, assignor to Telefunken Gesellschaft fiir Drahtlose Telegraphie m. b. H., Berlin, Germany, a corporation of Germany Application January 19, 1933, Serial No. 652,436 In Germany February 1, 1932 Claims.

The invention is concerned with a modulation scheme for short wave generators of the kind comprising the so-called Barkhausen-Kurz circuit arrangement predicated upon the principle 5 of field retardation.

The modulation of Barkhausen-Kurz generators in the past has been attended with certain difficulties for the reason that in the attempt to impress the modulator voltage upon the grid 01' the plate of the generator tube, not only the amplitude, but also the frequency of the ensuing oscillations is altered. The frequency of a wave generated in a Barkhausen-Kurz circuit arrangement is primarily predicated upon the operating potentials and the geometric data or factors of the tube. Thus, when a modulating voltage is superposed upon the static potential of the tube electrodes, the amplitude variations of the ensuing oscillations, of necessity, result also in a change in the frequency.

The object of this invention is to provide ways and means adapted to overcome this serious difficulty encountered in practice. According to the invention, the generator tube or oscillator is of the twin-grid type in which the second grid disposed at close proximity to the plate is given a high positive potential, whereas the plate proper similarly as in the conventional Barkhausen- Kurz circuit scheme, is kept at a slightly negative potential. The modulator voltages are fed to the first grid located closest to the filament.

In order to preclude undesirable capacitive actions between the'two grids, recourse may be had to a supplemental intermediate electrode which is maintained at a constant positive potential.

The object of the invention is illustrated in the drawing. Referring to the same, E denotes the thermionic tube, K the filament, A the plate maintained at a slightly negative voltage, and G the grid electrode kept at a positive potential. The oscillation system consists of a Lecher wire structure L coupled to the electrodes A and G. The modulation voltages are fed by any suitable modulator M to the grid electrode Gm. For screening purposes, another grid G5 is provided. The effect and operation of the arrangement is that, as a consequence of the influence on the space-charge effect produced by the modulation grid Gm the intensity of the current flowing to the positive grid G is controlled. The velocity at which the electrons fiy across the grid G is essentially a function only of the voltage of the grid G. Such electrons as travel at high speed through the grid G are braked by the plate field and they undergo pendulous motions between plate and grid.

I claim:

1. A Barkhausen-Kurz ultra short wave oscillation generator having, in combination, a pentode electron discharge device comprising an anode, a cathode, a control grid adjacent said cathode, an auxiliary grid adjacent said anode, and an intermediate screen grid, a source of potential for applying a high positive potential to said auxiliary grid, means for maintaining said anode at a much lower potential than said auxiliary grid, a source of modulating potential connected to said control grid, means for applying a suitable potential to said screen grid for screening purposes, and an oscillation system including a pair of parallel conductors coupled to said anode and auxiliary electrode.

2. A Barkhausen-Kurz ultra short wave oscillation generator having, in combination, a pentode electron discharge device comprising an anode, a cathode, a control grid adjacent said cathode, an auxiliary grid adjacent said anode, and an intermediate screen grid, a source of potential for applying a high positive potential to said auxiliary grid, means for maintaining said anode at a relatively negative potential with respect to said cathode, a source of modulating potential connected to said control grid, means for applying a positive potential to said screen grid for screening purposes, and an oscillation system including a pair of parallel conductors coupled to said anode and auxiliary electrode.

3. An ultra short wave transmitting system comprising an electron discharge device having an anode, cathode, a first grid electrode adjacent said anode, a second grid electrode adjacent said cathode, and a screen grid intermediate said first and second grid electrodes, means for supplying a high positive potential to said first grid electrode and for maintaining said anode at a much lower potential relative to the cathode and a suitable positive potential to said screen grid for screening purposes, means for applying modulating voltages to said second grid electrode, and a utilization circuit coupled tosaid anode and first grid electrode, Lecher wires coupling said utilization circuit to said anode and first grid electrode, and blocking condensers between said anode and first grid electrode and said Lecher wires.

4. An ultra short wave transmitting system comprising an electron discharge device having an anode, cathode, a first grid electrode adjacent said anode, and a second grid electrode adjacent said cathode, means for supplying a high positive potential to said first grid electrode and for maintaining said anode at a negative potential relative to said cathode, means for applying modulating voltages to said second grid electrode, means to prevent capacitive reaction between said two grid electrodes, and a utilization circuit coupled to said anode and said first grid electrode.

5. An ultra short wave system comprising an electron discharge device having an anode, .a cathode, a first grid electrode adjacent said anode,

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