US1930523A - Amplifying system - Google Patents

Description

Oct. 17, 1933. v. D. LANDON 1,930,523

AMPLIFYING SYSTEM Filed May 17, 1928 INVENTOR if. 5 W

- ATTORNEY Mfr/7022 0 16214621.

Patented Oct. 17,1933

N T D S A S AT OF EE I .msosza AMPLIFYING srs'rE' Vernon D. Landon, East Pittsburgh, Pa., assignor to .Westinghouse Electric & Manufacturing Company, a corporation of Pennsylvania Application May 17, 1928. Serial No 278 ,593 9 Claims. ('01. 179-171) My invention relates to amplifying systems, andithas particular relation to amplifying systems of the type wherein a plurality of thermionicv devices are utilized for the amplification of high' frequencies, the said devices being inter connected through transformers.

By reason of the fact that commercial'radio work is now'being carried on over a .wide range of frequency-channels, a commercial radio receiver must of necessity be so constructed as to be responsive vtor'nany more frequencies than the usualamateur, or broadcastreceiven'if the ,re-

ceiver is to be utilized in situationsfwhere it is not feasible to maintain separate receivers for each of a plurality of frequency-bands;

A single tunable transformer, of :the typegenerally'used for intertube coupling, is usually only efficient .over a relatively narrow band of ireof the tubes to the input circuits thereof through theqinter'electrode capacity, become very troublesome. It has previously been proposed to neutralize the tendency toward self-oscillation 40, by feeding back through a neutralizing circuit,

suflicient energy in opposite phase, to the unde-i sired feed-back to cancel the'latter.

Anti-oscillation systemsof many of the con-' ventional types give good, results over a somewhat limited tuning range, but necessitates constant. re-adjustment when plug-in coils or .transformers are used to cover a" wider range of frequencies. p i It is,*'.accordingly,- an object' .of my invention to provide an amplifying system capable of eflicientlycovering a much wider range ofcfrequericies than analogous systems constructed accord-' ing to the teachings of the prior art.

'Another object of my invention is to provide an amplifying system wherein any one of-a plusubstituting',,in the set, different groups: of-the ingall of 'the tuning elements thereof by means.

When a plurality, of thermionic devices are feeding back of energy from the output circuits rality of plug-in coils, or transformers, may be; utilized as an inter-tube coupling device without disturbingthe neutralization of the system against parasitic oscillations. e 1

Another ,object'of my invention is to provide a Q- plug-in transformer that shall be particularly adapted for use'in an amplifying system of, the aforementioned type.

In accordance with myinvention, I providea rad-i0 receiving system having,,as fixede1ements thereof, a plurality of variable condensers, each condenser being connected across the input -ter'-. minals of a thermionic device, and I furtherpro vide means whereby all of said condensers may be simultaneously adjusted by a single actuating 0% device. I provide also "a plurality of intertube: transformers, eachtransformer being mounted on a base having asymmetrically arranged plug terminals, Also, I mount one or more small variable neutralizing condenserson the saidibase,;

and so arrange the permanent wiring of the receiving. set and the connections of the"transe:

former to the neutralizing condenser, that, when the transformer is plugged into an appropriate" socket in the receiving set, the said neutralizing 8.

condenser is properly connected in the circuit," as well as the primary and secondary windings of. the transformer. h 1

The novel features that I consider character 'istic of my invention are set .forth with particu- 35 larity in the appended claims. The invention itself; however, both as to its organization and its methodof operation, togetherwith further objects and advantages thereof, will best be understood from a'consideration of the, followingdescription of a specificembodiment, taken 'i'n connection withthe accompanying drawing, in which.

Fig.v 1 is a-diagrammatic view of a portion of a composite amplifying system comprising several embodiments of my invention, I

Fig. 2. is a perspective view of a plug-in transformer constructed according to my invention,.a portion of the insulating wire-supporting form being broken away to show the manner in which a neutralizing condenserv is mounted in the interior thereof, Y i 1 Fig. 3 is a bottom .plan view of the deviceshown inFig.2,'-. I m

' Fig. 4 is an elevational view of the device Show "in Fig. -2, a portion thereof being sectionaliz'ed along aline correspondingtojthe line IV--IV of Fig. 3,and f Fig.- 5 is a perspective view showing the manner in which the openings in a socket device are so 1110 45 mediate. pointon the secondary winding is conarranged as to preclude incorrect positioning therein of one of the plug-in transformers.

Fig. 1 illustrates what might well be termed a composite amplifying system, in which two modifications of my invention are incorporated. The apparatus shown therein comprises a plurality of thermionic amplifying tubes 1 and 2 and a thermionic detector tube 3. Each of the tubes is of the usual type, having a filament 4, a grid 5, and a plate 6, and all of the tubes are supplied with plate potential from a common source 7. A common source 8 supplies potential to the filaments of the tubes, which filaments are connected in parallel to the source through a plurality of conductors 10 and 11.

A pair of telephones 12, or an analogous device, is included in the output circuit of the detector tube 3. A plurality of plug- terminal receiving elements 13, 14, 15, 16, 1'7 and 18 are associated with the first amplifying tube, being arranged as shown in Fig. 5, the elements 15, 16 and 17 being conductively connected to the plate, the grid and the filament, respectively- A variable condenser 20 constitutes a fixed component of the amplifying system, the rotary plates thereof being connected to the plug-terminal receiving element 18, and the stationary plates being connected to the grid of the tube and the element 16.

Aninput transformer, comprising a primary winding 21 and a secondary winding 22, is associated with the first thermionic tube by means of the aforementioned plug- terminal receiving devices 13, 14, 15, 16, 1'7 and 18. The transformer, which is shown in detail in Figs. 2, 3 and 4, comprises a cylindrical form 23 of insulating material,

on which are positioned the primary winding 21 and the secondary winding 22. A cylindrical closure 24, or base-member, is semi-permanently fixed in .one end of the insulating form 23 and carries a plurality of plug- terminals 25, 26, 27, 28,

30 and 31. The ends of the primary winding are conductively connected to the terminals 25 and 26, the ends of the secondary winding are con nectedtothe terminals 2'7 and 28, whilean interductively connected to the'terminal 30.

A neutralizing condenser, comprising a fixed plate 32 and a movable plate 33, is mounted on the base-member 24, the movable plate being adjustable toward and from the fixed plate by the rotation of a screw 34 which extends through a saddle-shape element 35 arranged transversely of the condenser and held on the base-member by a plurality of bolts 36. Access may be had to the adjusting screw 34 by removing a closure 37 which fits the end of the insulating form opposite to'the base-member, the said closure preventing, to some extent at least, the alteration of the condenser setting by dust or moisture.

The movable plate of the neutralizing condenser is connected to the terminal 23 and to one end of the secondary winding 22. The fixed plate of the neutralizing condenser is connected to a terminal 31 .to which no other part of the coupling device is:connected..

A. plurality of conductors 40 and 41 are connected to the fixed terminal-receiving elements 13 andr14,: respectively, which conductors may be included either in any energy-receptor circuit (not shown) or which maybe included in the output circuit of a preceding amplification stage.

It 1 will, accordingly, be apparent that, when the coupling device is inserted in the socket-elements, the inductor 22. is thereby connected in shunt'tothe tuningcondenser 20, and a reversed feed-back circuit is completed from the plate 6 of the device 1 to the filament 4 thereof, through the neutralizing condenser and that portion of the inductor comprised between the lower end of the inductor and the connection therefrom to the filament. The circuit thus constituted is that known to those skilled in the art as the Rice circuit.

The thermionic device 1 is illustrated as being coupled to the thermionic device 2 through an ordinary plug-in transformer, having a primary winding 42 and a secondary winding 43, although a coupling device similar to that just described could be used in this position, if desired.

The thermionic device 2 is illustrated as being coupled to the thermionic device 3 through a plug-in device constructed according to a modification of my invention. The later device comprises a transformer having a primary winding 44, a part of which is included in the output circuit of the thermionic device 2 and a part of which is utilized for neutralizing the tendency of the system toward self-oscillation, and a secondary winding 45, which winding is included in the input circuit of the thermionic device 3. The transformer mounting also carries a neutralizing condenser 46 which serves to complete a neutralizing circuit between the plate and filament of the device, as illustrated.

It lies. within the scope of my invention to utilize coupling devices of both of the types hereinbefore described, although, in any given receiver, it may be preferable to couple all of the thermionic tubes carrying high frequencies through devices of the same type.

It also lies within the scope of my invention to utilize either auto-transformers or tuned impedances as. coupling devices between thermionic tubes,.instead of the transformers illustrated.

When practicing my invention, the neutralizing condensers carried by each of the plurality of coupling devices necessary to cover a range of commercial frequencies are carefully preadjusted while the said devices are in position in the receiving set with which they are later to be used. 120 When, subsequent to the initial adjustment, it is desired to shift from one frequency-range to another, one group of coupling devices may be removed and another substituted therefor with full assurance that the neutralization of the set will 125 not be disturbed in the slightest.

When the thermionic tubes with which the coupling devices are adjusted are replaced by others, the neutralization of the set is substantially unaffected, inasmuch as the tube capacity is, in general, only a small percentage of the total distributed capacity of the inductors comprised in the coupling device.

My invention, therefore, proves of very marked advantage in the commercial reception of radio signals, in situations, such as on ship-board, where it is not feasible to operate a plurality of receiving sets, and where it is often necessary to rapidly shift from one frequency-range to another. 1

Although I have shown only two specific forms of my invention, it is deemed sufiiciently broad in scope to cover all coupling devices for highfrequency amplifying systems, and other amplifying systems, wherein a neutralizing condenser is a constituent part thereof and insertable therewith into a socket-device. My invention, therefore, is notto be limited except insofar as is necessitated by the prior art or by the spirit of the appended claims.

I claim as my invention: v I r 1. .As an article of manufacture, a coupling device comprising a plurality of inductorsfa supporting element for holding said inductors in inductive relation, a base-member in which said element is mounted and a neutralizing condenser mounted on said base-member.

,2. As an article of manufacture, a coupling":

device comprising a transformer, a base-member on which said transformer is mounted, plug-terminals on said base member, a neutralizing -condenser mounted on said base-member and connections between said transformer, said condenser, and said plug-terminals.

3. In combination, radiofreceiving, apparatus comprising at least twoth'ermionic tubes, a socket device, a coupling device comprising an inductor and a neutralizing condenser, the capacity of which is approximately the-capacity between two electrodes of a receiving tube, plug-terminals carried by said'coupling device, connections between said thermionic tubes and said socket 'deviceand connections between said inductor, said plugterminals and said neutralizingcondenser, whereby when said terminals are properly inserted in said'socket device, a circuit is completed for the,

transfer of energy between said thermionic devices through sa'idiinductor and said neutralizing condenser. v V

4. In combination; radio receiving apparatus comprising at least two thermionic tubes, a socket device therein, connections from 'said tubes to said socket device,a coupling device comprising an inductor and a neutralizing condenser,-plugterminals carried by said coupling device and connections between said inductor, said plugterminals and said neutralizing condenser, whereby, when said terminals. are p'roperlyinserted in said socket device, a circuit is completedfor the transfer of energy from bneof. said thermionic tubes to the other of saidtubes through said in.-

tially preventing dust andf'dampness from in- 37 ductor and another circuit is completed through i said neutralizing, condenser forpreventing the generation of parasitic oscillations. v

-: 5. As an article of manufacture, a coupling device comprising an inductor, an insulating form for said inductor, a base'for supporting said form,

a neutralizing condenser mounted on said base interiorly of said form and means for substanjuriously'afiecting said condenser. 6. As an article of manufacture, a coupling device comprising an inductor, an insulating hol- I low formfor said inductor, semi-permanent cloform for-said inductor, semi-permanent closures for the ends of said form, and an adjustableneuf tralizing condenser mounted on'one of said closures interiorly of said form, the other of'said'; closures being removable to permit the adjustment of said condenser. 8. As an article of manufacture, a coupling de- [vice comprising an inductor and a neutralizing condenser supported within said'inductor, the capacity of said neutralizing condenser being approximately the capacity between two electrodes of a receiving tube. I I

r 9,1 As an article of manufacture, a coupling device comprising a plurality offinductors and a neutralizing condenser, the capacity of which is 0 approximately the capacity between two elec-,

trodes of a receiving tube and a common support for both said inductors and said neutralizingcondenser.

VERNON D. LANDON. 115'

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