US1639414A - Radio receiving system - Google Patents

Description

Aug. 16, 1927. J. M. MILLER mu xo nnca1vmo svsrzu Filed Jans 23. 1926 Patent1ad Aug. 16, 1927.

UNITED STATES PATENT OFFICE.

JOHN M. MILLER, O]? PHILADELIE'IIIA, I'ENNSYLVANIA, ASSIGNOR T0 A'IWATEB KENT MANUFAC'I'UBIIN'G OOMPANY, DIE PEILADELPHIA, PENINSYLV'ANIA, A. OOBIOBA- TION OF PENNSYLVANIA.

RADIO RE'CEIVING SYSTEM.

Appliotion flled Juue 28, 1926. Sel'ial No117984.

My inmntion relabes to radiq rec eiving systems, and particularly those in which there is utilized a phn-ality 0f thermionic devices 01' vacuum tubes in caseade, with a variable tunihg device associated with each of tw o or more cf the thefmionic devices 01 vacuum tubes, and arranged t0 operate in conjunction with an absorption path, such as an open 01 looped antenna, 01' equivalent.

It is an object of my invention t0 make possible the a justment to like extents of the tuning devices of a. 1adi0 receiving system 01' set involving two 01' more circuits tuned to the 1adio frequency of the received energy, f01 effecting plural stage tuningg by moving the several tuning elements t0 substantially simi]ar positions, either separately 01' in unison with each other.

In accordance with my invention there is interposed between the first tuned circuit and the untenna. 01 equivalent absorption path, a radio frequency amplifier tube whose input 01' grid circuit is operatively related to the antenna 01' equivalent absorption path; neither the grid 01 input circuit 0f the interposed tube nor the absorption path is tunable t0 the various Wave lengths of the wave lenqth range 0f the received energy fo1 which the receiving system 01' set is designed, and the capacity and inductance 0f the input system, comprising the antenna 01' absdrption paph and the input or grid circuitof the interposed tube, are substantially constant throghont that wave ltength range, und the input system accol'dingly has n0 efl'ec t npon the tuning characteristics of and in eflect is reactively isolated from the first tuned circuit.

Further in accordance with my invention the inpnt 01 g1id circuit of the interposed tube is directly con'nected t0 01 in series with the antenna 01' equivalent absorption struc ture.

F urther in accordance with my irivention,

there may be shunted across the inpui: circuit of the interposed tube as by connecting it from grid t0 cnthode, an impedance, preferably an inductance, 0f such magnitude as substantially to exclnde radio frequency eur- 1ent 1"r0n1 the shnnt path but 10 permit passage 0f 10W 01 andio frequency current; to prevent substanfial eflect 1'1p0n the grid 0f the interposed tube by the efl'ectS, inductive o1 otherwise, upon. the receiving system caused by 10W frequency current in nearby lighting, power or other circuits; and further in a-ccordanee with my invention, the shunt impedance 01 inductance serves as a pah for the grid current of the interposed tu e.

Further in accordance with my invention, in an arrangemeflt of. the character aforesaid, the number of turns in the primary coils of the radio frequency coupling transformers in the anode circuits of the interposed andsucceeding tubes may be increaed, Without loss 0f stability 01' tendency to oscil- 1ate; and more particularly, the number of turns in the primary winding of the radio frequenv'y transformer in the anode circuit 0f the interposed tube may be greater than the number of turns in the primary coi1 01 coils of the radio frequency transformer or transformers in the anode circuit 0r cir-- cuitsnf the succeeding tube or tubes.

My inventio'n resides in a system of the- -This appliction is in pait a continuation of my application Serial N0. 73,091, filed December 4, 1925.

F01 an understanding of my invention'and for an illustration of some of the various f0rms it may take, reference is had to the accompanying drawing, in which:

Fig. 1 is a diagrammatic view 0f a radio receiving system in accordance with my invention.

Fig. 2 is a diagrammatic 'view 0f a circuit arrangement substantially similar 130 that 0f Fig. 1 with the addition, however, of a shunt inductance in the input circuit 0f the interposed tube.

Figs. 3 and 4 are diagrams 0f circuit arrangements explanatory of my invention.

Fig. 5 is a fragmentary diagramrhatic view of a modified arrangement involving a loop as distinguished from an open antenna.

Fig. 6 is an illustration of dial settings and of the corlesponding positions of the severa1 tuning elements.

Referring to Fig. 1, V and V are radio frequency thermiomc a1 nplifiers df the aulations,

fiIaments or grou several and various wava lengths lying within the range orwave lengths' t'or Which the set or system is designed, a5, for example, from 200 t0 600 meters.

The output circuit of the tube V is couled by the radio 'frequency step-up transormer T t0 the input circuit of the tube V similarly tunable t0 the various wave lengths of the sari1e wave liangth range by the variable condenser C In the grid leads of the tubes V and V may be included resistances 7 0f a magnitude to revent substantial regeneration 0r product1on of oscilit being understood that any other suitable arran ement IQI like purpose rnay be utilized. I he outPut circuit 01 the tube V is cou Ied by the radio frequency stepup trans ormer T to the input circuit of the detector tube V similarly tunable throughout the same wave length range by the variable condensenC. In the grid lead of the tube V is the usua1 g1id condenser C; and there may resistance r.

In the example above described, the adjustable tuning devices are condensers C, C und. C and they are similar to each other in the sense thab they efl'ect substant?ally e(ual changes in tuning when their rotors 0r a justable elements am moved or ad'usted through the same angular extents. hile there ma.y be utilized variable condensers of any suitable characteristic as regards change of capacity with change 0f osition of the roter or adjustable element, a type particula.rly suitable f'or use in carrying 0ut my invention is' such as illustrated in a general way in Fig. 6, and 0f Which it is chafacteristic that for e ual increments of angular ad- 'ustment of t e robor the capacitjy increases substantially equal increments; that is, t e increments of ca.1)acity are equal for mual angular displacements 0x increments oi a justment of the rotor.

The output circuit of cbupled by an audio fre uency transformer T, whose primgxry ma.y shunted by ghe radio frequency by-pass condenser C, w1th the in ut circuit of the audio frequency ampli er tube V whose output circuit is coupled b the a1'1d.io frequency transformer T with t le input circuit of the audio frequency amplifier tube V in whose output circuit is the signal-translating instrument I, such as a loud speaker, telephone 01 the like. As usual the several fila'ments f are supplied bv current from the source A, the indiv1dual s thereof having rheostats in series thexewit if desired; and the anode oircuits ardsu plied by the source B, 10W voltage prefera%ly being impressed upon the anode circuii; of the detector V, intermediate voltgge upon thb anode circuits of the tubes .V, und V: and high voltage upon the anode'cirouits of the tubes V and V.

the detector V is be providd a grid leak 'cured upon the shafts As thus far described, the system is an ordinary tuned radio frequency amplifier set, the tuned input circuit 0f whose first stuge tube V is ordinarily coupled 130 the radiant energy absorption structure, such as an antenna closed loop 01' the like.

\Vhen the tunable input circuit 0f the first stage, as V of such an ordinary tuned radio frequency amplifier system is coupled by a transformer 01 equivalent to an antenna o1 equivalent absorption 'structure which generally has different characteristics. 0r lengths in difierent installations, the antennaor equivalent absorption structuro uperates in effect as an inductive 0r capacitative renotance, generally capaJcitative, across the. terminals of 01 in shunt with the prirnary of the coupling transforr'ner, and, therefore through the coupling introduces reactance irito the tunable input circuit 0f the first stage. Ths fach und the further fact that the effective reactance of the antenna circuit 0x path varies with the wave length received, causes the adjustable element 0f the tuning device 0f the input circuit of the first stage t0 take positions, in tuning t0 the several wave lengths of the range, which donot correspond the pdsitions cf the adjustable elelnent 01 elemen ts 0f the tuning device or evices 0f the succeedinq stage o1 stages. In such cases the extent nf adjuStmenfi of the adjustable element. cf the tuning device C for auch first stage, as in (hangihg from resonance f01 0116 wave le ngth to resonance fdx' another wave length, does not correspond with the extent of adjustment 0f the adjustable e1ernent 01 elements 0f the 'tuning device C 01 tuning devices C und C of the succeeding stage 01 stages in changing from.resonance f0r that one wave length t0 resonance for the other wave length. It is necessary, therefore, f0r the Operator to find the proper setting ab a given wave length for the tunin; device (J ar1d the properbut difierent, setting for the tuning device C f0r thesame w2we length. Generally the setting of the third tuning device C will correspond closelv with that of the second tuning device However, satisfactory operation of the sei; involves the delay und x mcertainty of making two difl'erent settings which are not alike as regards the postions of the tuning elements and the dials co-operating therew1th.

In Fig'. 6 the dials D, D and I) are seof the rotors nr adjusfable elements R, R anti R, respectively, of the tuning condensets C, (J -and C whose stators are indicated a1: S S and S". respectively. E3011 dial may be uniforml v graduztted i"rom zero (a0 100, for example, within a half circle, whose ends at zero and 100 (01'- respond, respectively -.w'ith the minimlnm and maximum capacities of the condenser, the maximum capacity exceeding by litt}e with -2md materially dliTer fr0m.

or nothing the capacity required 130 tune 170 the longest wave of the range for which the set is designed. When, for example, the proper setting for a given wave length of either 01' both f tl1e dials D and D is sa.y, 33, the setting of the dial D of the first stage V when coupled as usual t0 the antenna 01' absorption -structure without interposition of the tube V later 120 be described, will be materially different from and n0t uniform with the settings 0f the dials D and D T0 insure that all the dials shall have substantially the same setting for each of the various wave lengths, enabling the operat0r to move all dials to the same setting for sharp tuning for all of the tuned circuits f0r each of the various wave lengths received, or to permit, as indicated in Fig. 6, the :idjustment to equal extents in unison with each other 0f the swcral adjustable elements 0f the several tuning devices I interpose between the first radio frequency amplifier tube V, whose input circuit i.s tuned, and the antenna F, Figs. 1 and 2 01' loop antenna G, F ig. 5, or equivalent absorption structure, a radio frequency amplifiel tube V, Figs. 1, 2 und 5, whose ontput circuit is coupled by the radio frequency transformer T .to the tunable input circuit of the tube V. The tnnable input circuit of the tube V is by the transformer T related to the anode circuit of the interposed tube V in substantially the Same way that the tuned input circuit 01 circuits of the later stage 01' stages is 0r a1e 1elated t0 the immediately preced'ng anode circuitor circuits t0 which it 0r thev am similarly coupled by transformers 01 T. Accordingly, the first tunable system 01 circuit of the series is n0t materially influenced as regards its tuning character?stics by the antenna 01' absorption structure, and, therefore, with similar tuning devices in and f0r the several tunable systems 0r circuits, they may be tuned to the several difl'exent wave lengths of the range by substantially similar and equal extents 0f movement of the adjustable tuning elcments. By such arrangement, the antenna 01 absorption structure does n0t introduce either inductive or capacitative reactance int0 the first tunable circuit or system of the series, und the first tunable cirquit orsysfem accordingl v has characteristics dependent upon its own electrical constants, und. therefore, its tuning characteristics are similar t0 those 0f the succeeding stage OI stages making pnssible the adjustment of ndjustable tuning elements to like extents and to like positions 'f0r each of the several wave lengths of the range f0r which the sei: or system is desigmed.

Referring again to Fig 1 the absorption o1 antcnna path, comprising the antenna F und the ear@h 0r countercapacity E is counected direct-ly, that is, without Coupling 0f any character, to the rid and cathode f of the interposed tu e Neither the antenna 01' absorption ath nor the input circuit of the iniserpose taube V is tuned er tunable to the various wave lengths 0f the range fo'r which the set or system is to be utilized.

With such an arrangement the electromotive-force of radio frequcncy corresponding with the frequency 0f the energy absorbed by the antenna m other absorption structure, is eflective in substantially full magnitude f01 varying the otential 0f the grid of the intorposcd tuhe V, particularly since the sn1all capacity bctween the grid g and cathode f is effectively in series with the relatively larger capacity of the antenna 01 absorption structure.

The rcactance 0f the antenna 01 absorption structure, therefnre, does not afl'ect the First tuned 0x tunable circuit 0f the series 0f tnnable circuits and. in consequence, all (hree rotors R, R and R of condensers hnvlng the same characteristic as regards change 0f tunixg with change 0f position of rotor may be arljusted t 0 similar positiuns for tuning to the smne wave length 0f the received energv. \Vhere the rotors are adjustable independently 01 each other and euch is provided with a dial, rhe three dials may, therefore, be m0vod to corresponding readings to assure tuning t0 the same wave length.

Howcvvr, the three rotors may be mechanically coupled as by the bands k und z passing over pulley p on the shaft of 10t01 R und over the pulley p arid p'- 0h. the shafts 0f the r0fms R and R respectively. A sing'le dial will then suflice secured upon the shaft 0f any 0ne 0f the rotors and its rotation will eflevt adjustment Of the rot0rs in unison. tn like oxtents, fol tunng t0 auch of thc wmu lengths of the range.-

W'here a receivmg system 01' set of the chmacfer described in mnnection with Fig'. 1 is used when adjacent to a circuit ca1rying 10W frequency fluctuating 01 alternating current, as a power circuit 0x a lighting circuit in the same residencc m building wirh the recoiving set, there will be induced in the receiving syslenrlow frequency electromotive-forces affecting -at like frequency the potentinl 0f the glid 0f the interposed tube V with the'xosult that a ditnrbing 10W frequenc v 1mm 01 n0te Will be prodnoed by the translating instrument I, For example, in the c-ase of a lighting circuit in a residence where the receiving system is utiliznd, the alternating current 0f commercial fre quency, for exam 31e, 25 t0 cycles per sucond. will cause a um 0: note of correspor 1ding frequency in the instrm nent I. O1 in fact any circuit traversed by 10W m nudi0 frequency current and disposed witbin the range of influence upon the me'reiving system will cause a 10W o1 audio frequency note 01' s0und in the instrument I.

In Fig. 2 there is illustrated an unangement f01' preventing substantial effect by such 10W 0r audio frequency currcrrt. Fig. 2 corrcsponds generally with Fig. 1 except that thoxe is utilizedin addition the industance L shunted ac1oss the input circuit of the interposed tube V by uonnection from grid 10 cuth0de thereo-t.

The inductance L is 0f such magnitude that it cnnstitutes in eficct a choke coil su1 stantiully pz-evienting passuga therethrough 0f current 01' the radio frequoncy of the received energy. The rcaction cf the inductance L fu1 10W 01 aud.io frequency current, however, is 10W, thevoby shunting the 10W 01' audio frequency current, dm: t0 an adjacent 10W 01 audio frequency circuit, from the g1'id g 015 the interposed tube V thereby p1eventing productiori 0f low 01 audi0 frequency sound by the instrument I.

Fig. 3 is a circuit representative of the antenna 01' absorptiqn structure and the grid to cathode path of the interposed tube V which, as regards the received radio freq1xenuy energy comprises in efiect a sourcc H of rudio frequenoy electro-motive-forcc in saties with the capacity K of the antenna or absorption structure and the capacity between the grid und. cathode 0f the interposed tube V, the latter ductm 1ce L. The capacity K, even f01 a small 01' short antenna, 1s large with respect t0 the capacity k, und the indutance L is of such a magnitude as to operate as a radio frequency choke, thereb preventing radio frequency current irom y-passing through choke coil around the capacity k. In con sequence, substantially the ful1 magnitude 05 electro-motive-force set up in the ahtenna by the received energy is eifective across the g1id und cathode of the tube V and the inductance L has substantially no effect in the scnse 0f reducing the otential variati0ns of the grid of the tube As regards 10W or audio frequ6ncy, howo\b1'. the arrangement of Fig. 2 is s ubstant-ially that of the ci1cuit ind1cated in;Fig. 4 in which J represents a source of ]ow freqn0m*y electro-motive-force impressed upon H e reueiving system through a capacity K which in this instance is small as compared \\'ifh flw capacit K of Fig. 3, since the 0apncib: between t c receiving systqm and the circuit traversed by 10w 0x audio frequency currcnt is quite small. The somce J :md capacity K are in ef1'ect in series with each other and the capacity k existing betweian the grid and cathode of the tube V, the latter capacity again shunted by the inductance L whose magnitude is suc as to by-pass tl1e low or audio frequency current around the capacity k, causing but slight, iiE siny,

difi'erence of potpntial between grid undnitndes 0f the shunted by the incathorle of the tube V at 10W 01 audio frequency, with the result tlmt the receiving system is not :1fiected by a neighboring 10W 0r audio frequency circuit.

The incluctzmce L is of further advantage in that it provides a conductive path f1om gridL t0 cathode (51' tl1e tube V to prevent bl0cking thereof upon occurrence of streng static 01 other atmospheric disturbances or 01? powerful Signals fr0m 0the1 01 nefl.rby stations.

In lieu of an open nnienna 215 shown in Figs. 1 und 2, there nmy be utilized a loop antcnna G as indicated in Fig. 5. The 100p as in the case 01" the antenna F, is dimct-ly connected, \iri1;1101113 coupling 0f nny character, t0 the grid m1d cathode 0t' the interp0 0d tube V. Hexe again the inductance L of the character and for the purposes de- Sc1ibed in connection With Fig. 2 may be shunted across grid und cathode. The magrid to cathode capacity of the tube V of' F1g. 5, 0f the shunting inductance L und the distributed cap-ucity 0f the 100p G am such o1 so related to the inductance 0f the 100p G that high radio frequem C V vnltage is immesed upon the grid at the fu1l magnitude 0f the l'adi0 frequency voltage existing across ehe terminals of the 1001) G.

In the arrangements 0f Figs. 1, 2 und 5. the inpnt path 0I circuit of the interposed tube V is not tuned 01 tunable to the different wave lengths 0f the range for which the set is designed.

\Vhile in ordinary tuned ladio flequency amplifying Sets involving f0r example, the tubes V V and V with tuned input circuits, and the first of these tuned input circuits coupled t0 the antenna 01 absolption structure, the number of turns in the primary coils of the transformers T, T und T has generally heen 8 to 10 when 201 tubes are utilized. By recourse to the interposed tube V related to the antenna 01 absorption Structure as herein described these primaries may have, without loss of stability of the set. a greater nurnber ofturns, efi'ecting ir'1crease of amplification and so compensating, at least in part, for the loses m absence of resonance in the antenna 01 absorpti0n path anc1 in the input ath 0r circuit of the interposed tube F01 example, the number of turns in the primaries 0f thc transformers T and T may be incrensed to the order of 13, and the number 0f turns in the primary of the txansf'ormer T may be mad6jggreater than the number cf turns in the primaries cf either 01' both the tmnsf ormers T and T and may be 0f the order.qf 22. In addition to these increases in number 0f primary turns it is possible to red uce the magnitudes ofthe stabilizing res1stance5x r.

While f:he variable tuning levices above described are condensers, it will be under-- stood that my invention comprehends also variation of inductance in lieu of variation of capacity in any one 01' more of th tuned circuits.

What I claim is:

1. A radio receiving system comprising the combination with an absorption structure, of a receiving set comprising a plurality of three-electrode thermionic devices in cascade and at least one of which amplifies the absorbed radio frequency energy, devices associated with said thermionic devices for tuning circuits in cascade to the same wave lengths throughout the same range of wave lengths und means for insuring thut the adjustable elements of said tuning devices shall partake of equal extents o:E movernent in adjusting from resonance f0r one wave length to resonance for another wave length comprising a threeelectrode thermionic amplifiel whose output circuit is coupled t0 the input circuit of the first of said thermionic devices and whose grid and cathode are directly connected with said absorption structule.

2. A radio receiving system comprising the cornbination with an absoxption structure, 0f a receiving setcomprising a, plurality of three-electrode thermionic devlces in Cascade and at least one 0E which amplifies the absorbed radio fre uency energy, devices associated with said t erm1onic devices for tuning circuits in cascade t0 the Same wave lengths throughout the same range of wave lengths, means for insuring that the udjustable elements of said tuning devices shall partake of equal extents of movement in adusting from resonance f0r one wave length t0 resonance for another wave length comrising a three-elect10de thermionic ampli- Eex whose output circuit is coupled to the input circuit of the first of said thermionic devices anal whose grid and cathode am nonreactively conductively connected with said absorption structure, and means mechanica1l coupling the adjustable elements of .saic tuning devices t0 cause them to partake of movements in unison.

3. A rad1o receivmg system compr1slng the comb1natlon W1th an absorpt1 on structure-of a receiving Set comprising a plu ra1ity of three-electrode thermionic devices in cascad' and at least one of which amplifies the absorbed radio frequency energy, clevices associated with said thermionic de vices for tuning circuits in cascade to the same wave lengths thr0ughout tl1e same range of wave lengths, means for insuring that the ad'ustable elements of said tuning devices shal partake of equal extents of movement in adjusting from resonance foi one wave length t0 resonance for another wave length comprising a three-electrode thermionic amplifier whose output circuit is co}gmled to the input circuit of the first of sa1 thermionic devices and whose grid and cathode are directly connected with said absorption structure, und an inductancacom nected between said grid and cathode and having such magnitnde as substantially to prevent passage therethrough of rece1vqd radio frequency energy and to by-pass 10W frequency energy from said grid. y

4. A radio receiving system comprising the combination with an absorption stracture, 0f a receiving set comprising a plura]ity of three-electrode thermionic devices in cascade and at least one 0f which amplifies the absorbed radio frequency energy, de vices associated with said thermionic devices for tuning circuits in cascade to the same wave lengths throughout the Same range of wave lengths, a radio frequency transformer for transferring radio frequency energy ir0m the output circuit of one of said thermionic devices to the input of another of said thermionic devices, means for insuring that the adjustable elements of said tuning devices shall partake of equal extents of' movernentin -ad'usting from resonance for one wave langt to resonance for an other Wave .length comprising a three-electrode thermionic amplifier interposed between said absorption structure and the first of the circuits tuned by the first of said tuning devices the input of said last named amplifier and said absorption structure coustituting an input system the magnitudes of whose inductance and capacity are substam tially coristant, and a l;ad1o frequency trans former transferring radio frequency energy from the output c1rcuit of said interposed thermionic device to the input circuit of the first of said first-mentioned thermionic devices, the number of turns of the primary winding of said second-named transformer being substantially in excess=of the number of turns of"th primary of said 'first-named transformer.

5. A radio reoeiving system comprising the combination with an absorption struc hure, of a plurality of circuits in cascade, means :for tuning each 0f said circuits, am]

a three-electrode vacuum tube interposed between the first of said tuned circuits and said absorption structure, the input of said tube and said absorption structure constituting an input system the magnitudes of whose inductance and capacity are substantially constant and so related to said tunable circuits as to permit ual movements of their tuning devices in a justing from reso nance for OII wa.ve length to resonance for another wave length.

{ 6. A radio reoeiving system comprising the combination with an absorption structure, of a plurality of circuits in cascade, means for tuning ea.ch of said circuits, a three-electrode vacuum tube amplifier in- III tervening between a pair of said tuned circuits und having '1ts input tuned by t-he first 0f said pair, a resistance for reducing the tendenay 0f said amplifier to produce 052'11- lations connected in series between the inpub eleetrodes 0f said amplifier and the first tuned circuit of said pair, and a three-electrode vacuum tube interposed between ehe first of said tuned circuits and said absorption structure, the input 0f said last named taube and said absorption strueture constituting an input system the magnitudes cf whose inductance and capacity are subsiantially constant and so related to said tunable circuits as to permit equal movements of their tuning davices in adjusting f1om resonance f0r one wave length to resonance fo1 another wave length.

'i'. A radio receiving system compms1ng the combination with an absorption structure.- of a plurality of circuits in cascade, devices associated with said circu'1ts 10r tuning them t0 the same wave lengths throughout the szune range 0f wave lengths and means f01 insuring that thendjustable element.= 0f suid tuning devices snail partake of equal extents 0f movements in adjusting f1om resonance for one wave length to resonance for anocher wave length cornprising a threeelectrode vacuum tube intgrposed between the f'1rst of said tuned dircu1ts anti said ahs0rption structure, the input 01 said tube an 1 said absorption structure constituting an input system the magnitudes 01 whose inductance and capacity are substaw tially constant.

8. A radio receiving system compr1s1ng the combination with an absorption stracture. 0f a plurality of circuits in cascade devices associated with said ciruits f0r tuninq them to the -same wave lengths througzhour the san1e range 0f wave .engtha means mechanicaliy coupling the adjustable elements 011 said tunin devices f0 efl"ecting their adjnstment in unison to equal gaxtents, and means f01 insuring that the ad}ustabia elemen%s 0E said tuning devices shall partako 0f equa] extents of movement in adjusting from resonance for one wave length 150 resonance for another wave length comprising 21 three-electxode vacuum tube interposd befween the first of said lnn9d circuirs and aid absorption structure. *he input 0f :=nifl h1be and said absorption structme oonstituting an input- System the magnitude9- f whosc inductance and capacity are substantially constant.

9. A radio receiving system comprising the combination with an absorpcion structnre 0% a plura1ity of circuits in cascade a variable condenser for tuning' eacn 0f said circuits. and means for insuring thnt sai condensers shall partake of equal extents of adjnstments from resonance for 0n0 wave Iength to resonance for another wave length cnmprising a three-electroe vacuurn tube interposed between the first 0f said tuned circuits and saic1 absorption structure, said absorption structure and the input 0f said tube constituting an input system the magnitudes 0f whose inductance and capacity are suhstantially constant.

10. A radio receiving system comprising the combination with an absorpiion structu1e, of a plurality 0f circuits in cascade, 21 variable condenser for tuning auch nf said circuits equal increments 0f adjustments 0f each of said condensers effecting eqnal increments of its capacity, und means f0t. insuring that said condensers shu]l partake of equal extents 0f' adjustments from resonance f01 one wave, length t0 resonance f0r anothe1 wave length comprisinq a tl1ree eletrode vacuum fube interposed between the first 0f said tuned circuits and said absorption structure, said absorptiu stumture und the input 0f said tube constituting an input system the magnitudes of wh0se inductance and capacity am substantially constant.

11. A radio receiving system uomprising the combination With an absnrption structure, 0f a plurality of circuits in mscade. a variable condenser f0r tuning cach of said circuits equal increments: 0f adjustrnent Of each 013 said condensers efi'ecting equnl increments of its capucity, means mechanically coupling the a ljustable vlements 01: said condensers f0r efl'ecting their a-djustment in unison to equal extents, and means for insuring that said oondensers shal] partake of equal extents 0f adjustment from resonance f01 one wave lc'ngth t0 resonance for another wave length comprising a threeelectrode vacuum mbo interposed between the first 015 said tuned circuits and said absorption structure, said absorption structum und the input 0f said tube constituting an input system the magnitudes 0f whosc inductance und apacity are substantially comstaut.

12. A radio receiving System eomprising thu vombination wit'h im absorption shrnch1re, 0f a phnaiity nf circuits in cscade. the induvtance 0f eavh of said Circuits hzfving fixed magnicude and comprising a. winding of a coup]ing transformer.- a singile variable mndensvr constituting the so19means fm tuning each 0f said circuils, and means f0r insuring (hat the adjustabie eiements 0f said mndensers sha1l partake 0f equal extents nf movement in adjusting {mm resonance for one wave length to respg xztnce for another Wave 1ength compris'mg a three-elecfmde vacuum tube interpozr'i between the firstnf said tuned circuits und said absorptinn structure, said absorptioh stmicture and the input of said tube constitutingan iriput system the miignitpudes of wliose inductance and capacity are substantiallyoonstant.

13. A radio r'eceiving system comprising the combination with an absorption structure, of a plurality 0f circuits' in cascado means f0r tuning euch 0f snid circuits, und a three-electrode vacuum tube having its output operatively related t0 the first of said tnned circuits and having its input electrodes non-reactively conductively con nected with said absorption structure. said absorption structure und the input 0f said tube constituting an input system the magnitudes of whose inductance and capacity am substantiallfy constant und so related 130 said tnable circuits as 10 pexmit equal movements 0f their tuning devices in adjusting from resonance fol' one wave Iength tomesonunce f01 another wave length.

14. A radio receiving sysfem comprising the combination with an absorption strncture, of u plurality 0f circuilzs in cnscade, means. for tuning eacb 0f said Circuits. a three-electrode vacuum tube interposed between the first of said tuned circuits nnd saiclabsorption structure, the input 01 said tube und said absorption structu1e constituiin;; an input systemthe mugnitudes 0f Wh0se inductance und capacity am substantially constant throughout the wnve length range of the receivec energy and so re lated t0 said tnnabl'e circuits as t0 permit e ual movements 0f their tuning devices in a jusfing frorn resnnance f01' one wave length t0 resonnnce f0r anothmwave Iength, and an inductance cnn'nected between the gxid and cathode 0f Elid tube und having such magnitude as suhstantially ro prevent passage therethrough of received radio frequency energy and t0 hy-pass lowfrequendy energy from said grid.

15. A ra'dio receiving system comprising the combination with an absorptibn structure, of a receiving set comprising a plurality of three-electrode thermionic devices in cascade and at least one of which amplifies the radio frequency energy, condensers' associated With said thermionic devices f01 tuning to the same wav'e Iengths throughout a Fange of wave lengths each of said coudensers comprising roter and stator elements 0f such character that the incrcments of capacity am equal f0r equal increments of adjustment 0f tl1e roter with IBSIJN'1Z t0 the stator, and means for insuringr that rhe rotors 0f said condensers shal] pnrtake of eqnal extent 0f movement in :uIjustingfrom resonance for one wave length to resenance for another wave length comprising a, three-e lectrode thermionic amplifier whose output circuit is coupled 10 the input circuit 0f the first 0'1 said thermionic devices am]. whose input is operatively related to said absorption structure, the inpu'r 0f said last named thermionic device and said absorption structure c0nstituting an input system the magnitudes 0E whose inductance and capacity am substantially constant.

16. A radio receiving system comp1ising the combination with an absorption structure, of a receiving set comprising a plurality of three-electrode thermionic devices in cascade and at least one of which amplifies the radio frequency energy, condensers associated with saicl thermionic deviceg f0r tuning to the sa1ne Wave lengths throughout u lange of wuve lengths, each of said Condensers comprising rotor and stator elements 0f such character that the incrementg of capacity Ire equal for equal incrernents 0f adjustment of the rotor with respect-to the stator, means mechanically coupling the rotors of said condensers for efiecting their adjustment in unison to equal extents, and means f01' insuring that the circuits tunable by said condensers shall be simultaneously resonant to the same wave length comprising a three-electrode thermionic amplifier interposed between the first tuned circuit and said absorption structure for reactimly isolating them from euch other, the input 0f said la'st named thermionic device and said absorption structure constituting an input systen1 the magnitudes of whose inductance and capacity are substantially constant.

17. The methpd of tuningcascaded circuits throughout a frequency range of energy received upon an absor ti0n structure, Which comprises reactivey isolating sid absorption st1ucture from the first 0f said tuned circuits while permitting the transfer of received energy from said absorption structure thereto, maintaining said absorption structure non-resonant t0 the received energy througrhout said frequenoy ranga, und mnving the adjustable tuning elements 0f said circuits to equal oxtents in tuning said circuitg from resnnnce f0r one frequency [0 resonance for another frequency 0f said received ener JOHN MILLER.

13. A radio feceiving system comprising the combination with an absorption structurc, 0f a plurality of circuits in cascadc, means for tuning each cf said circuits, and a threeelectrodc vacuum tube having its output operatively related t0 the first cf said tuned circuits -and having its input electrodes non-reactively conductively comnected with said a'bsorption structure. said absorption structure and the inpnt 0f said tube consrituting an input system the magnitudes of whose indnctance and capacity a1e substantiali%y constant a.nd so related t0 said ttmable circuits as to permit equal moven1ents of their tuning devices in adjusting from resonance for 0ne wave Iength t0 resonance f01 another wave length.

14. A radio receiving system comprising the combination with an absorptinn structure, of a plurality of circuits in cascnde, means for tuning each 0f said circuits a three-electrode vacuum tube interposed between the first of said tuncd circuits und saidcbsorption sfructnle, the input cf said tube and said abscrptinn structure c0nstituting an input systemfl1e 1nagnitudes of wh0se indu0tance and capacity aro substantially constant throu hout the wnve length range 0f the receive energry and so relaied t0 Said tunablb circuits as t0 permi equal movemenfs cf thei1 tuning devices in adjusting from resonance f01' one wave longth (0 resonance for anothcr wave length, and an indnctnnco cnn'nected betwcen the grid and cathode 0f said tube and having such. magnitude as subsfantialfy toprevent passage therethrcugh of' received radio frequency energy and to by-pass lowfrequency energy frnm said grid.

15. A ra'dio receiving system comprising the combination with an absorption structure, of a recciving rality 0f tl1rec-electrode thermionic devices in cascade und ab least onc of which amplifies the radio frequcncy energy, condensers associated with said thermionic deVices for tuning 130 the same waVe lengths throughout a Fange cf wave lengths, cach of said comdensers comprising roter and stator elements 0f such chmracter that tl1e inc'remonts of capacity arc equal fr equal increments 0f adjusfrnent of the roter with respcct t0 the stator,- and means f0r insurinp: that 1he rotors cf said condenseyg shall pwtake of equal extent of movernent in zuljust- 1 Certificate Patent N0. 1,639414.

set comprising a pluing -from resonance for one wave length to resenance for anothar wave lengrh comprising a three-electrode thermionic amplifier whose output circuit is ccupled f0 the input circuit of the first cf said thermionic devices and whose input is operatively reiated to said absorption structure, the inpuf 0f said last named thermionic device and said absorption structure constituting an input systcm the magnitudes 0f whose inductance and capacity are substantially constant.

16. A radio receiving system comprising thc combination with an absorption struc ture, of a receiving set coxnprising a plurality of three-electrode thermionic devices in cascade und at least 0ne of which Implifies thc radi0 frequency energy, condensers associatcd witl1 said thermionic devices for tuning to the same Wave lengths throughout l 1ange of wuve lengths, each 0f said c0ndensers. comprising rotor and stator elemonts 0f such character that the incrementg m capucity E1I'0 equal for equal increments of m]just1ncnt cf the rotor with respect-to the sfator, meuns mechanically coupling the mtors of said condensers for efl'ecting their adjustment in unis on t0 equal extents, and mcnns for insuring that the circuits tunable by said condensers shall be simultaneously resonant to the same wave length comprising u threcelectrode thermionic amplifier interposed bctween the first tuned circuit and said abscrption structure f01 reactivcly isolating them from each other, the input cf said la'st named thermionic device and said absorption structure ccnstituting an input syste1p the magnitudes 0f whose inductance and capacity are substantially constant.

17. Thc mcth od 0f tuning cascaded circuits throughout a frequency range 0f energy received up0n an absor tion structure. which comprises reactivey isolating sz1id absorption structure from the first 0f said tuned circuits while permitting the transfer cf received energy from said absorption structure thereto, maintaining said absorption structure non-resonant to the reccived cnergy throughout said frequency range, und 1noving the adjustable tunin elements of said circuits to equal cxtents in tuning said circuitg from resnance for one frequcncy t0 resonance for another frequency of said received ener JOHN MILLER. of Correction.

Granted August 16, 1927, to

JOHN M. MILLER.

It is hereby certified that error appears in the numbered h'ne 25- an Word pulley mad pulleys; read mauement; same the WOI'd adjustmeuts atent requiring eorrection as' follows:

the word rotor in Iine9l insert a page G line 27, claim 7,. fr page, hnes 64, 77, and 81, claims 9 read adjwstwwvat; read ezvtents; und that the said Letters Patent should be therem that the same may conform to the record of 6th :Eay of Decemher,

rinted spe cification of the aboveage 3.. aitisr the nume ral 2 in cgmma and in line 102. for thc the Word movements und 10, respectively, f0l' page 7, ]me 55, for the Word extent read with these corrections the case in the Patent Office. A. D. 1927.

M. J. MOORE, Actz'ng C'ommisn'0ner cf Patente.

Certificate of Correction.

Patent N0. 1,639414. Grarited August 16, 1927, to

JUHN I\1. I\IILLER.

It is hereby certified that grmr appears in the printed spe cification 0f the above numbered patent requiring correction aus follows: Rage 3. sfter the nume ml 2 in line 25 and the w0rd roter in line 91 insert a cg;nma and in line 102. for thc word pulley read pulleys; pagu 6 Iine 27, claim 7,.fi the word movements read movement, Same, page, lines 64, 7T, and 81, claims 9 und 10, respectively, f01' the word adjustments read adjustmmat; page 7, line 55, for the Word extent read ewtents; and that the said Letters Patent should be read with these corrections therein (hat the same may conform to the record 0f the case in the Patent Ofiioe.

Signed a.nd sealed this 6th day 0f December, A. D. 1927.

Tsnu] M. J. MOORE,

Aoting ommissimzer of Patents.

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