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Publication numberUS926934 A
Publication typeGrant
Publication dateJul 6, 1909
Filing dateJan 20, 1906
Priority dateJan 20, 1906
Publication numberUS 926934 A, US 926934A, US-A-926934, US926934 A, US926934A
InventorsLee De Forest
Original AssigneeForest Radio Telephone Co De
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Wireless-telegraph tuning device.
US 926934 A
Abstract  available in
Previous page
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Claims  available in
Description  (OCR text may contain errors)



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4% mjzzw Patented July 6, 1909.





Patented July 6, 1909.




f onrrE-D s'rA'rEs PAT NT OFFICE.


wmnLnss-rnnnenarn TUNING DEV'ICE.

Specification of Letters Patent.

Patented July 6, 1909.

Application filed January- 20, 1906. 2 Serial No. -.2 96,931.

- 0. whom .may concern:

it known that I, LEE DE FOREST, a citizen of the United States, and a resident of 4 ew- York, in the county of 'New York and 5 State of New York, have'invented a new and useful Improvement in Wireless-Telegraph Tuning Devices,of which the following is a.

V specification.-

- .My inventionrelates' to wireless telegraph systems, more particularly, receivingv sys-.

- terns, and has .for its objects certain new and mproved a paratus ,,and circuit arrange- Inents where y an antenna or its associated circuit, or both, may be, attuned to a given "1;? frequency which, ina receiving system, is that of the electromagnetic waves intended to affect the responder included irrsaid asso ciatedcircuit,

. For the puripose of morefully disclosing above-stated objects; but it, is to be under- 'stood that I do not limit myself to the particular forms'of apparatus and. circuit arrangements 'disclosed' inasmuch asmany mo ifications may be made therein without 39 departing from the s )irit of my invention.

n the drawings, Figure 1 is a front elevation of a wireless telegra h tuning device: Fig. 2 is aside elevation t ereof; Fig. 3 isa perspective view of the device shown in Figs.

: l and 2; Fig. 4'is a side elevation of a modifi cation; Fig. 6 is a se ctional View of another modification taken on the line 6 6 of Fig. 7 Fi 7 is a-side elevation of the device shown in i 6 and Fig. 5 is a diagram showing one fway 1n which. the devices'illustrated in Figs.

' 4 and 6 may be employed.

Ijtis possible to enhance the distributed capacity effect of a flat spiral tuning device such as shown in my U. S. Letters Patent 4 No; 852,381, dated April 3 O, 1907, by using,

.instead of awire, afiat strip or ribbon, preferably of copper'or brass wound tightly upon itself to form a spiral, the -convolut1ons of which may be separated by a thin ribbon of silk insulation or a thin coating of cellulose acetate. A flat spiral so formed'of thinly insulated metallic ribbon is much more erficicnt than a flat spiral formed of thinly 1nsulated wire because of the increased ,d is 'tributed capacity effect, and either oisa d fiat spirals is much more effective than the simple solenoidal or helical tuning coils now commonly employed for tuning wireless telegraph circuits, even when-said coils are closely wound and consist of small, thinlyinsulated wire, while a solenoidal tuning coil having the'same number of turns of large, heavily insulated wire is not at all efiicient.

The tuning. device shown-in Figs. 1, 2 and 3 may bemade by winding along copper or brass ribbon ,1 of, say, 100 .i'eet' in ength, into a spiral with a thin silk ribbon 2 between the conductors and securing the spiral to a suitable support 3 ofinsulating material. In lieu of the ribbon insulation 2, I may coat the metallic ribbon 1 with a thin layero'f any suitable insulating compound, such as cellulose acetate. One terminal of the spiral, herein shown as the outer terminal, may be brought out to a binding dost 4 and an adjustable connection may e made with the spiral by means of the contact arm 5, pivoted to the su port at 6, or by any other means suitable or the purpose. The two leads a and I), connected in the present case to the binding post 4 and pivot 6, serve. to connect the spiral to an antenna or to a circuit asso ciated with said antenna.

For the sake of avoiding confusion in the drawings, the parts are not shown to scale, 35 but it will be understood from the foregoing description that? the several spires of all the tuning-devices herein described areso close together that the movement of the-adjustable contactdevices across the face of said spirals varies the amount of metallic ribbon in cluded in a circuit connected to a'and b in a continuous manner, and hence varies the distributed ca acity and distributed in ductance ofsuc circuitin like manner. The spiral ribbon tuning device shown in 1 Figs. 1, 2 and 3, maybe emplo ed for attun- .ing an antenna or its associate circuit and it may be em loyed also in lieuzof the wire spirals in t e wireless telegraph receiving systems described in my Patent No, 852,381 referred to above;

In Fig. 4, I have shown a very efficient transformer-condenser of which the primary and secondary consist of metallic ribbon spirals constructed as above set forth in con-. nection with Figs. 1, 2 and 3. This transformer-condenser may-conveniently be constructed by ti htly winding intoispira'l form two metallic ri bons 7, 8, placed one over the other and separated'by silk or other insular" tion, and may have'its primary and secondary connected to separate circuits at the 4 C is a-condenser and each. be attuned to the fiequency of vwaves to be-received.

transformer-condenser illustrated Fig; 4,

pointsa, b, and c, 11, respectively. In order to apply the adjustable contact featureto the Ernnary and secondary spirals, the two ribons,7, 8, may be effect, as shown, so-that' the pivotedcontact 9 .will make connection with the face of s iral 7 and the contact 10, with faceof spira .8. l I

In Fig. 5,.A re resentsan' antenna groundedat E and inc udin is a responder includmg the secondary's-piral 8. By'means of the contacts 9 and 10,- shown diagrammatically in. Fig.5 by the points 6 and d, the antenna system A7? 1E and local circuit C 8 R, -may Figs-band 7 show a modification of the by means. of which themutual inductance and. mutual capacity can. both be conven-.- lently adjusted. lnthese figures, .the spiral" ribbons 7, 8 aremounted o'ninsulating sup:

ports 11; 1 2, respectively,intowhichspiral grooves. are-cut for holding the spiral rib-' bons. Contact buttons 13, 13, are inserted in the-back of the supports and are electrically. connected in a progressive manner with successive portions of their respective spirals,

so that the movement of the contact arms 9,

' 10 over said buttonswill vary'the amount of ribbonincluded in the circuits which are ThusIiOr exam v connected to thespirals. ple, the buttons a,, c, may be connected with the outerends of the spirals 7, 8, respectively, corres ending to the oints a, c, in

Fig. 4, while t e buttons as an y may each be connected to the innerzend of spiral 7 and the; intermediate buttons on support 11 may each be connected to intermediate points along spiral, so that a' movement of the arm.

4 .9 frome to e would'produce the same effect as the movement thereof frorn a to 'y. "The buttons 13 on support 12 may be similarly arranged. Bymoving the supports 11, 12

away from or toward each other the two spiralsy', 8. which fit into each other, and;

. prising a tightly wound spiralof conducting ribbon, and a'movable contact -member an which are insulated by air or by a layer i0 7 of cellulose acetate if desired, mayb separated to a greater or lesser degree, and the mutual inductance and mutual capacity may be correspondingly varied. The dia am shown on Fi 5, applies tothe transormer-condenser llustrated. in Fig.


well as to that illustrated in Fig; '4, the.

and c, d, of Fig. 6 correspondg to a, b and c. respectivelyyof Io aim:

1: A wireless telegraph tuning device con sisting of a spiral of metallic ribbon and-a contact operating transversely across said sgiral whereby the ca aclty and inductance t e'reof may be v arie ina continuou s man-.

ner. i I

2. A wireless telegraph tuning device comranged 'to move transversely-With respect t e saidspirally wound ribbon for" vary ng the,

number of effective spires thereof. I

3. ln a wireless telegraph-system,'an an- .tennaand a tuning device consisting of a iral of metallic ribbon serially'and adjustofsaid spiral.

.4. In a wireless" telegraph'systemjan an;

tenna and a ma s' iral of metallic ribbon serially connected t erewith' and having its distributed 'ca-.

pacity and inductance so adjusted that the natural period vof said spiral and antennais equal to that of the waves-to b ereceived, in

combination" with an associated circuit in--.

binding a tuning device consisting oti'a spiral of metallic ribbon having its distributed capacity and inductance so adjustsd that the natural period of said associated circuit-alsois. equal to that of said waves.

device consisting 'ofa:-

In testimony Whereofil have hereunto subscribed my name this 17th, day of JanflQOfi.

Witnesses; I

] Penn? Fannswoarn,

Lns rnla Trisrnnn.

s i a ly connected therewith andla contact do vicearranged to be operated across the edges

Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US2629081 *Apr 26, 1950Feb 17, 1953Collins Radio CoHigh-frequency inductor
US2892138 *Feb 7, 1957Jun 23, 1959Stanford C StoneVariable capacitor
US2927291 *Apr 15, 1957Mar 1, 1960Ruehle Robert AVariable alternating current coil constructions
US3170134 *Dec 15, 1961Feb 16, 1965Westinghouse Electric CorpElectrical coil structure for inductive apparatus
US3189858 *Jan 11, 1961Jun 15, 1965Westinghouse Electric CorpMagnetic core structures
US3553476 *Aug 3, 1967Jan 5, 1971Tdk Electronics Co LtdOsicllating elements in parametron devices
Cooperative ClassificationH01Q1/38