US1243789A - Valve-receiver for wireless signals. - Google Patents

Description

G; M.-WRIGHT.

VALVE RECEIVER FOR WIRELESS SIGNALS. APPLICATION FILED MAR. 13. 1911 1,243,789. Patented Oct. 23, 1917.

' I UNITED. STATES PATENT v onnron.

' ononon MAURICE wnronr, 0? LONDON, Enchant, nssronon 'ro mncom wmnnnss TELEGRAPH COMPANY OF AMERICA, .N'EIKT YORK, N. Y., A CORPORATION OF NEW JERSEY.

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Patented Oct. 23, 1917.

Application filed Eareh 18, 1917. Serial 1V0. 154,580.

To all whom it may concern: -Be it known that I, Gnonon MAURICE WRIGHT, a subject of the King of Great Britain, and resident of Marconi House, Strand, London, England, have invented a new and useful Improvement in Valve- R-eceivers for Wirele$ Signals, of which the following is a specification. This invention relates to receivers ofwireless signals which comprise a vacuous vessel containing a heated filament, a grid and an anode. I

'According to this invention I connect the oscillatory circuit carrying'the oscillations to be detected'to the grid and anode, and I provide means for applying a steady potential to the gridwith respect to the filament, and I am thus enabled to limit the current which can flow in the anode circuit. One important result of this will be that a the sounds caused by atmospherics in a telephone will be reduced and will thus be prevented from overpowering the sounds caused by the signals which it is desired to detect.

With this arrangement the space between the grid and anode constitutes a detector or conductive coupling of extreme sensitiveness for very small values of limiting current, the limiting current being decided by the brilliancy of the filament and the potential at which the grid is maintained with respect to the filament.

I-prefer a'brightly glowing filament and: -a potential adjusted to give a, very small limiting value to a dull filament and a potential of a higher value.

A very small potential difierence between the anode and grid is necessary for adjustment, at the most a small part of a volt as distinguishedv from tubes employed for magnifying. I find that the tubes work best at the highest possible vacua and I prefer grids of a fine mesh.

My invention is illustrated by the accompanying drawings, Figure 1 of which is a diagram showing my invention adapted for .use as a detectoriand Fig. 2 is a modification -'in which two tuned oscillatory clrcults are employed connected to each other by a con ductive coupling. Fig. 3 shows a curve of current for difierent potentials on the anode, the abscissze A representlng potentials and the ordinates 0 current. Fig. 4 shows a modified form of valve in which the grid and anode are so formed that they completely surround the filament. I

In Fig. 1, a isa vacuous tube containing a grid (1, anode e and filament b heated by battery 0 in series with a resistance 8 for adjusting the, brilliancy ot the filament. Though the grid and anode are shown in the conventional manner, I prefer to so form the grid that it completely surrounds the filament, and the anode that it surrounds the grid. This construction is shown in vertical section in Fig. 4. An inductance f, coupled to an aerial i'and shunted bya condenser g, is connected to theanode e and through a potentiometer p to the grid d, and is coupled to a telephone receiver m by coupling The grid 0? is also connected by a variable contact to a resistance t across thebattery c. For a given position of this variable contact on the resistance t, a certain limiting current can flow across the space between d and c with a given brilliancy of the filament; This maximum current I call the saturation limit or saturation current. The circuits are so arranged that the brilliancy of the filament can be adjusted by s, the potential of the grid can be adjusted by t, and the most sensitlve point on the rectifying curve can be utilized by p, so that signals can be heard in the telephone, the maximum strength of these signals being limited by the adjustment of t. That is to say, by varying the potential applied to the grid with respect to the filament, the operator can make only a small portion ofthe filament In Fig. 2, signals in the aerial are transferred inductively to the circuit f g, and the space between the grid 03 and the anode e acts as a conductive coupling between the two circuits f g and 7c Zby completing a circuit through k, g, potentiometer p, 0, and f the circuit is, Z being coupled to the detector circuit a. The limiting value of the current is controlled, as before, by t and the sensitive pointisfound by the potentiometer p. g is a choke coil and r a condenser shunting it, and o is a reaction-coil for balancing acofmorethana' certain strength. Moreover,

sounds caused by static disturbances might otherwise-be louder than the signals and overpower the latter. This limitation of the signals and other responsive sounds in the receiving circuit is obtained by varying the current in the filament Z) so as to control the brilliancy thereof, and consequently the quantity of electrons which may be given off by the filament, as well as by varying the position of the contact at If to control the potential between filament b and grid g. The latter adjustment is the preferred one and is used as far as possible, being more efficient, since the distinctness of the received signals is maintained practically unimpaired, although their maximum loudness is limited. This result is due to the quick rise of the current to its maximum, the rate of increase of the current increasing. with the brilliancy of the filament and the maximum current for a ing determined by the position of the contact at t. The method of limiting'the re ceived signals by reducing the brilliancy of the filament is disclosed in British patent claim is:

1. In three-element vacuous detector, comprising anode, grid, filament and heat: ing battery, a resistance connected across the battery, and a conductor connected at one end directly to the grid and at the other end by an adjustable contact to the resistance, said filament and heating battery being otherwise disconnected from said anode and grid.

2. The combination of a .vacuous vessel containing a grid, an anode, and a filament, a battery connected to the terminals of said filament, a resistance-connected across said battery, to said grid and at the other end to an adjustable contact on said resistance, in comgiven brilliancy be- 1 a conductor connected at one end neespse bination with means for impressing the oscillations to be detected on the grid and anode only, all for the purpose described.

3. The combination of a vacuous vessel, containing a filament, a grid, and an anode, means for heating the filament to varying degrees of brilliancy, tential applied to the grid and having a value of the same order as the potential drop across the filament, means for adjusting this potential to obtain any required saturationlimit, and an oscillatory circuit connected to the anode and to the grid, said adjusting means being connected to said oscillatory circuit only at said grid. 7

a. The combination of a vacuous vessel containing a grid, an anode, and a filament, a heating battery connected to the terminals of said filament, a resistance connected across said battery, a conductor connected at one and directly to said grid and at the other end to an adjustable contact on said resistance, and an oscillating system for receiving signals connected to said grid and anode, said system including means for applying an adjustable potential across said grid and anode, said filament and heating battery being entirely disconnected from said system except for the connection of said conductor directly to said grid.

5. The method of operating a vacuous com.

tamer having a filament and anode therein, With a grid intermediate said anode and filament which consists in impressing a con-.

tinuous M. F. on saidfilament, 1mpressing a portion only of said E. M. F. between the grid and filament, and impressing intermittent potential impulses across the grid and anode, .but none between the filament and grid.

6. The combination of a vacuous vessel containing a grid, an anode, and a filament, means for impressing a desired continuous potential across said filament, means for impressing between said filament and grid a portion only of said continuous potential, and means for impressing oscillations to be received between said grid and anode only, the connections being such that no intermittent potential impulses are impressed on said filaments.

a n rmally fixed po-,

' In testimony that l claim the foregoing as my invention, T have signed my name this 16th day of February, 1917.

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