US1839650A - Transmitter system - Google Patents

Description

Jan. 5, 1932. J. w. COOK 1,839,650

TRANSMITTER SYSTEM Filed Oct. 30 925 wwgges f 5B W W Patented Jan. 5, 1932 3 naiiajen srArr-is.

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. waanej e a 1 KAN-5A5 mnaus virr'rnn s ysrnm 4 Application filed .October 30, 1926. Serial'No. 145,117.

The main. ob'ect. of. thewinventionris. an;

improved means .for producing modulate.dy

high frequency currentsor curreritsabdve audiloility in Whichv the ,modulat edthighj ire: quency currents. are notfurtheif modulated.

by the. disturbances from. the conductors connected to the output side oflthetrans nitter; Such. a conditiomvouldexistWhenthet ans: mitten would be connected to unEtlYaIlSp se d, wires. insignaling service,- This is accom: plished by inductively.couplingthe.gridand plate circuits and inductively, coupling the output: coil: to avoid. dire t. on ect on. e; tween: the. elements. o the generating, means and between the outputcircuiu ;By directy connectinga y.part tthehigh equency. g n ra ng. me ns to. nil-transpo ed; Wires. would produce dis rtion. uato ind tive. leakage from the Wires modulating thehigh. 9 frequency currents. High frcquency jcurrents are currentsaloove audiloility in follow; ing references. v v

. The n tan oi n. t eoss lationpirr. cuit are not a part of the line or antenna d c c it n erefo e the. equency ir h?" Wave radiated will not change ith slight ha g s, n. t ei d ct ncept he e co ls:

. Th s pa ati -t n ng Q l iW t assoce ate/d menses f o ir o tae pne with .i o ucesa ery able andmara powerful generat on of a frequency on rents e o e pmt uning ot heldifr, talent l men d y. lr. r angement, in the circuit causes both tubes to mutually.

-1 aicl each other in producing highfrequeiicy currents and modulating same as willlh eflde scribed.

By the use ofa transforme coil havingfa primary secondary ratio h gh enough" toex i d o. cite'a voltagflon'lihe ofthe uhe modulated. oscillator, wherein two valves or i e p larity. and. on d. o the st tube :o ei ppcsiie. P a ity, igh ihe o taee.. n.t eplat s l e pecti e u s; ancli ghl mpeda c f who c dary coil also: tends to keep the load on theisec- 55 Qesl ry ide 0t t e a s o mer. l. 1?- ll F 0 esi ances ot e means are required tohold the load on the transformer coil. 4 Connected injseries in the grid ci icui t' of thesecond tube is a battery which provides a negative grid bias whereby the plate. current is decreased throughithe seconclqtuhe. necessary as the secondtubeactsas an oscillator with thefirst tube aiding its action. Just as each mutually'a'ids'i n the modulation of the high frequencymcurrents. Ifthe plate filament curr'ent 'i'n thefirsttubeand in the se conjd'tub e \Yi: egqualithere vould b61110 frequency currents g nerated, By means of tvvoor more heavy choke coils of approximately two henries each in value seli'ies in thepositivelead and two or more heavy choke coils of values of approximately UVQ henries each in the negative lead of the plate current source andshunting the cur? rent sourcebetn een the chokfe coils With condenser 'capacities" of one .or more micro fara ds each it is possible to keep a nearly fixed cur rentsource on the plates ofithe tubes and by so doing keep back any varyingfoffthe current source; such as would be caused by, the current sou'rcefeeding other circuits. Machines "s'upplyii1g' other circuits and the plate circuits ofthe tuhes Wouldbean example;

Tl1e" l1eavy inductance's and condenser shunts inplate power supplyleads holds the positive negative voltages .commonto the plate circuit or the first and second tubes very nearlyconstant durin the mutually aiding f action between the rst and second tube; Z

The abo ve enumeratediobjects and the ad vantages of. my improved system will. all be more fully comprehended from the follovving: detaileddes'cription of the accompanying drawings,,'whereinz, v 1

"Figure l is a diiagrammaticview of a prodi1ce'r' ,a.ri'd transmitter of ahi'gh freqneii'cy;

his

tubes are connected in parallel through variable air condensers, for use in telephone or voice transmission.

Figure 2 is a diagrammatic view illustrating the systems shown in Figure 1, except that the system in Figure 2 has been modified for signal transmission.

Figures 1 and 2 are diagrams of the transmitter system in which the output terminals of the system are shown at 10, 10. Connected to these terminals are an air core inductance coil 11 and a variable air condenser 12. This coil 11 is in variable inductance relation to the air core inductance'jcoils l3 and 1d; coils l3 and 1d are shunted by variable air condensers 15 and 16. 17 and 26 illustrate vacuum-tubes or valves containing grids, plates and" filaments; 18 is a rheos'tat in the filament circuit, 19 is a potentiometer shown interference from the current source for the plate circuit and to prevent any reactance from the current source. 23 is a telephone transmitter and 24 is a current source connected in "series with the primary coil of an induction coil 25 which is of a very high ratio.

i As the general arrangement of the circuits is substantially the samein the various illustrations, similar elements have been designated by the same reference characters in the two figures. Figure 2, Where the same general arrangement of the circuit and elements shown in Figure 1 are employed, illustrates the adaptation of my improved system for the transmission of signals.

In this figure, instead of employing the transmitter 23, I employ a relay of low resistance 28, which has a key 29 and a battery 30 connectedin series, in order that the relay armature may be opened and closed 5 the opening and closing of the relay armature being induced by the opening" and closing of the key 29; the relay armature opens and closes a set of spring contacts 31 which produces positive and negative pulses from the battery 2% to the primary of coil 25.

The action of the improved transmitter system is described as follows: From the arrangement of the elements in the circuit,it can be'seen that the circuit is in a condition for producing modulated high frequency currents. That is, the inductance coil 14 in series in the plate circuit of the generator tube 17 causes a magnetic excitation of inductance coil 13 in series in the grid circuit of the generator tube 17 when current'source is supplied to the tubes and in turn excites back on coil'lt which cont nuous acting-back frequency currents. By inductively connecting the inductance coils 1a and 13 with the. output coil 11 without direct connection between the plate or grid or output circuits, any disturbances, due to inductive leakage from line wires connected to it are prevented from modulating the high. frequency currents generated. This arrangement also permits a better adjustment of the grid and plate circuits of the transmitter as they are not directly'connected. As the inductance coils n the generative or oscillation circuit are not a part of the line or antenna circuit, the frequency or the Wave sent out or radiated Wlll not change with slight variations in the inductances or these coils, thus making a more stable circuit.

' bince the plate of tube is directly connected tothe magnetically excited coil 14 which is in the plate circuit of tube 12", and the grid circuit of tube 26 is directly connected to the magnetically excited con 15 in the grid circuit or the tube 17, a condition is brought about whereby tube 26 also acts as a generator or oscillator of high frequency currents and which results in more powerl'ui high i'requency currents being produced by the transmitter circuit. This can be seen by removing tube 26 from the "transmitter circuit andnoting the decrease in high frequency currents generated compared with tube 26 in circuit. must be very nearly liXed in this circuit and this is accomplished by the insertion of two or more heavy choke coils of an approximate inductance of 2 henries each in the positive side ofthe plate current source and the insertion of two or more heavy choke coils of an approximate inductance of 2 henries each in the negative side of the. plate current source and shunting the current source with capacities connected between the choke coils and connected between the current source and the choke coils. l

A battery 27 is connected in series with the negative side to the grid of tube 26, whereby the plate space current in tube 26 is reduced'to a value very much below the plate space current flowing through tube 17. in tests made, the best results were obtained with a current of .025 ainperes flowing through the plate. circuit of tube 26 and1125 starting-oscillations of the high frequency current. Thesecondary of a high ratio transformercoil 25 is also connected in series with this battery between the grids of tube 26 and of tube 17. This transformer on the'plate circuit causes generation of high coil 25 has a very high ratio so that when aciso tuatcd by its primary circuit means, it exerts an alternating voltage charge on the grid L of tube 26 higher in voltage than the voltage of the plate current supply of tube 26. Likewise, as the grid of tube 17 is connected at the opposite end of the secondary of transg former coil 25 and also through the filament path, the grid of tube 17 receives a grid Voltage charge of opposite polarity to grid charge on tube 26. This grid action being opposite in both tubes at the same instant increases the plate current in one tube and decreases the plate current in the other tube and since the plate battery source is constant, a decrease in plate flow through one tube increases the plate flow through the other tube by its parallel connection,thus both actions accelerate the modulation effect.

It'can be seen that tube 26 generates high frequency currents due to its connection in I was accomplished after tests by use of thehigh ratio transformer coil 25 whereby a grid voltage charge could beobtained that would produce the greatest efiect on the plate current possible, and likewise since tube 26 plate space current had been lowered by connecting battery 27 in the grid circuit to prevent shuntingthe generator action in tube 17, a much stronger varying voltage charge was required on the grid of tube 26.

The current action through the three element tubes may be explained as follows:

The grid filament clrcuit of tube 26 and the grid filament circuit of tube 17 are connected in series with a common circu t through the filament battery resistance shunt and filament connections. Tube 26 grid filament circuit is connected inseries through the secondary of a high ratio transformer 25, high voltage battery 27 and filament resistance shunt 19. Tube 17 is connected in series with inductance coil 13 to the same resistance shunt 19, the negative side of battery 27 is connected to the grid of the tube 26, and the voltage of this battery is of such a value that it produces a high negative value on the grid of tube 26 through the high resistance of the transformer coil secondary; Thus the amount of plate space current through tube 26 is much lower than the amount of plate space current through tube 17. When variable currents are sent tube have one path common to both circuits, namelythefilament' connections and the connection to battery resistance shunt 19, any

variable like change inone circuit will produce like changes in the other. tubes act as modulators and likewise from their parallel connection in the circuit both actvas oscillators. i

I have described what I believe to be the simplest adaptations of my improved system; it will be understood, however, that certain modifications may be made-without departing from the spirit of my invention;

a, i l a dwltti r teen; 2 Asrhe nafilament; ar ues or each Thus both i it being also understood that my improved transmitting system is adapted to operate in conjunction with the wires or conducting means-of telegraph circuits while said wires or conducting means are in service. For example, one wire may be in quadruplex telegraph service and one wire maybe in printer telegraph service; and any suitable number of valves connected in multiple may be employed to function in the manner hereinbefore described; the present application relating to subject matter divided out of my pending application Serial No. 21,486.

VVhatI claim is: Y 1. In a transmitting system two three element tubes both acting as oscillators and modulators having a common battery source connected through a variable resistance to the filament circuits of said tubes, with a voltage source connected across the plate filaan adjustable resistance connected across the filament battery of said tubes and a connection from the negative side of plate battery source to the common side of the grid filament circuits of said tubes, said grid filament circuits being connected in series, one through the secondary of a high ratio transformer coil and high voltage battery to a Y variableresistance shunted across the filament batterysource, the other through an impedance coil shunted by a variable con denser to the same variable resistance connection; 7

2. In a transmitting system two three element tubes having a common battery source connected through a variable resistance to the filament circuits of said tubes, with a voltage source connected across the plate filament circuits of said tubes inseries withan adjustable resistance connected across the filament battery of said tubes and a. connection from the negative side of plate battery source to grid filamentcircuits of said tubes,

its ment circuits of said tubes in series with 4 ipaageab' 5 grid filament circuit being connected in series through an inductance coil to said filament reslstance shunt,

IYJOHN W. 0001;.

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