US2326801A - High frequency tubes and circuits - Google Patents

Description

Aug. 17, 1943. G. E. PRAY ETAL 2,326,801

HIGH FREQUENCY TUBES AND CIRCUITS Original Filed Sept. 22, 1938 Patented Aug. 17, 1943 'snan mizqiinncy Geor ge E rrflay aiid sebastanmwatoaeg ri v -"riginal app1ica;ti0n September 22. 195 8, .saia' "fl $31 ,215,- mwtmatem -NQ.- 2,,2514951, iaatea. r 1

A gust 19.41 '1) anua y 122,; 1 3

This invention relates to vacuumftuhesffofu e with ultrahigh radio including such tubes. I

Among the several are:

To provide vacuum tubes in :iivliichi catho' grid transit time losses are' reduedtbaQni mum;

To provide vacuum tubes .-ne arly ele t cns nrfihe aihed= 3 form path lengths for grid space;

To eliminate ture; g: g .1, 1:5 To provide vacuum tubeswith high shun imp dan si I 3.2,.

To .providevacuum tubes with electrode capacities;

objects of etk a e eddy eurrents'in' man a I To provide, .in .vacuuni tubes t ti e-i br more beams of electrons,-.icontrollablehy, potentials aplied to the tube-electrodes;

To provide circuitsand icperating: utilizing tubes of the-type .ahDVfl-=IHQDlIJ-DQ Q- :.-In the drawingz J Figs; 1 and 2 '.are,. respe.ctiyeb 5 section and .a .lon'gitudinalsection :of tube according. to .ounpresentinventitm Figrs iis a schematic I diagram ;-of;

te'ctor; f Fig. 4 illustrates the "use/010m tubeas :a mixer in connection with alccal oscillation-i112.

Fig. 5 is a transversetsectionwof a tubei'accord-l ingto-our invention havingamultiple centre and having a focusing plate icon-direct; trons -to a.sing1e anode; "j

with its individual. 'contnol electnode push pull operati'on. 1;

This application is .a division I. use. n:

9f ourln oepen mg. application Ser. No. 23-1,'215,-fi1ed1 septentber zz 19S8 Patent-No. 225L951, August,l2,gli94 l.' For amplification; detection; or osciilationizat positive. M My o H .the" istance. from the cathode to. thegi id'before transvefse.

Ea, duoid eda- 2 utilizing the above-mentioned. tube. as; aide-Q,

' for faflnormaispacing of" foruse'at'fnequencies aboveiltlfimegacyclesw fatednegt ve'gridand positivean'ode (brjs'creen' it fusing fa --t e tro;de or' pentodef); fictentials, thief" time requiz ed for "an electr rig-to .go; from-"the;

Fig.6 uti1izes thesame form omocusin -Qhte' as Fig.. 5, but has "two separate :a 'fld 935F15 frequencies of theorder 01 megacyciesxrpen second and upward, --the vacuuiii tubeinput i n'ithe "emciency of the tube we e;

sacrifice in the resonant game: the the input elements of the tube also niese .a; low

' pedance'andthe'cathodeto gi i delecti'orr 'transit time are the most important; factorsflimiting 1 circuit is application.

V greatly reducidQwithfuftheflossin Y sensitivity and lossbf seigctivityiff f Thisilowishuntresistance dueto 'tr'a;nsitti'nie tion; we will consider "a -vacuum 'tupe trioderw-ith an el'ecitrorii emitting cathode iorf'filament-fan j.

anode'whose potential is positive-with respect;

to the cathode, and a "contr:o1 'eieetrode b'r gridf w js im eniia is. va 'e isipu al re 1. tive to negative with'respect-tofthe(cathode;

' The cathode wilifen it a'suppljo'f elections with T aife'. faiwn frbm the space charge layer, theyfar e H replenished by 'fu1 ther cathode emission.- Since maintained positive, the 'pctential thefah'ode so "close I;

seem 2 the g di-""curi cut."is affected;- andffi om :cathode to before the fan'od'e' current; i s afiected.

Therit; it-uneq a isa y lowicq par' t mi anode l otentialfso {the ,velocity inipaftedftcan electron in'thje cathod eagrid space'fisjvery small compared jtcfthe'velofcity in .tjhefgifid-anode space. hu t e h d =er i m .v ma y:

times greater than the grid fnode; transitti ne I .1

he e ctrodesgandis the r important iafctor to consider; j;

- In "the vacuum tubes com'mercia y avai cathode jot, filament to the grid 'is of" the rd'e T of 210: s eonds.'= f At fllow frequencies this e1 is" negligible com pa ed to "the period .0 oscillationfbut as the frequency 'is' incre edtransittime 'becor nies'a larger-portion for heaters.

The component of current in phase with the negative gridvoltage has the efiect of greatly reducingtheinput impedance of the tube and consuming power from the input circuit. f I

The electrode'materials used in our novel tubes may be any of those well known in the art as suitable for the various purposes, such as tungsten or nickel alloys for grids r controlfelectrodes;. I.

molybdenum or nickel alloys for anodes, suppressors, or focusing electrodes; "nickel alloy sleeves coated with oxides of barium, strontium carbonate or thorium for cathodes, and tungsten.

All the electrodes are normallysupported and their spacing kept constant by} means of mica'discs at the ends of the electrodes. As hereinafter used, the term strip electrode is to be understood as designating an detector or mixer in a superhetero-dyne circuit. The circuit elements are the same as in Fig. 3 except that the output impedance is here a resonant circuit comprising an inductance 45' and a capacitance 46; the outputenergy being taken off through inductance 41 coupled to inductance 45. The output impedance is-resonated to a desired intermediatefrequency derived from beating the output of local oscillator 48 with the input radia frequencyx In Fig. 5 the construction is modified byhav- ;,ing;a single; anode 13, a single control grid 14, a single acceleration grid and a single focusing plate 'lli that extends around the cathode 58 in spaced relation thereto from adjacent one side of anode-13 to adjacent the other side thereof,

" thus having at least three quadrants around the electrode whereof the length is notably greater,

than the width and, if transversely curved, not subtend more than a-few degrees. V

The embodimen of our invention. shown in Figs ..l and 2 is a duo-diode'intended for opera does frequencies." Within the. glass envelop is dis- Posed the, cathode. support 30 having electron emissive bodies 3| and 32 on diametrically'opposite sides thereof and'facing the emissiv bodies arethe electrodes 33and 34. The electrodes 33. and 34 are placed yery close toi the respective emissive bodies, the spacing between an electrodeo and its coacting emissive' body being but a few cathode enclosed by the focusing plate with the anode ,13 between the terminii of the plat It but outside. the 'spaceenclosed thereby. While thefocusing electrode could be extended to encloserall the electrodes; this is undesirable due tion as a detector or-rectifierat very high radio to the increase resultf Operation at high frequency usually makes it desirable'to utilize balanced, or push-pull input circuits, feeding into a balanced tube circuit. In the case of a single sided tube, that is, one having, one "control electrode and one anode, it is in output capacitancethat would necessary to use two tubes to obtain a balanced circuit. The connection between the separate thousandthsof an inch; The areasof thesurg faces of electrodes 33fand Mare substantially equal to the areas of tlie'respective cbactin emissive bodies 31; and 32 and the surfacesfiof the anodes are substantially uniformly spaced:

from the, surfaces of the emissivebodiesgwhreby electron paths of luniformlllen'gth areprovided between the emissive bodies and the. electrodes.- The electrodes aa nc'u'may have widths of .of an inch and a length of /8 01 an'inchwhichj gives a low input cameraman the order cross. micromicrofarad; giving satisfactory operation at frequencies above 500'megacycles persecond. A detector circuit employing the tube of Figs.

1 and2is -shown schernatically in Fig. 3, whereinthe electrodes 33 and- 34 are respectively con-,

nected to the parallel members35'and 3B of a resonant frame; This frame comprises the.mem-.

bers 3 5;and 3B; which may be-shortrods of conductive material having low resistance connected at .their end remote from the tube by albar 31,

; with. a conductive tuning. slider 38 contacting both bars. The bar t! is provided to reduce dead end losses and the slider, may be moved to. resonate the frame, as is well knownin this art. --A variable capacitance 39 may be connected across the frame to provide additional tuning if, desired. The input leadsto slider 38 aredesig- Y natedby tll and and bylmeans thereof the alternating potentials are applied" to electrodes 33- and 34; The cathode bodies :31 and 32 are connected through a suitable resistor lz to, the slider38 andthe-output leads 43 areconnected to the opposite terminals of resistor 42 which may be shunted by a capacitance 44; This'circuit acts asa full'wave detectorior rectifier; the radio fre-' 'quency signalsjbetween electrodes 33 and .34; h-j ing substantially 180 degreesout. of pliasefwith', each other, and the demodulated'output appears acrossthe'output impedance 42; 44. The resonant frame isfound to'be more advantageousthanfthe conventional inductance for 'frequ cies above 200' megacycles'persecond; I

Fig.-4 depicts our duo-diode'used as theffirst anodes 11 and 18 and the cathode 150. In this.

tube the electron stream flows continuously toward the anodes,'but since the control electrodes l9 and have applied'to'them' radio frequency potentials that differ substantially degrees in phase-the electrons will be attractedto one anode and-kept away from the other during onehalf cycle and then attracted to. the, other and kept iaway'from the one during the next, half cycle. -It is thus seen that this tubeoperates as a'balanced or'push-pull unitwhile the electron stream continues to flow in the same gen:

eral direction; If Ldesired,z accelerating grids may-"beused'in :this type of." tube. :A single vspace charge gridor a single: screentgridgor both, should work satisfactorily withthe double elementsgof this tube.. j

--Wherever in this; specification definite values are stated they. are given by way of illustration. and not. ..1imi iQ I he invention herein described and claimed aybe used. a d. ma i sture by 'bi-fb t e G vernment oi t Urine? States-ref new for governmental purposes without the payment of-anyroyalties thereon ortn'e'reror;

'WefclainhI; v '1 'jl'." An"'electr on" f charge device, comprising a cathode support; separate electron emisslve bod-' ies on opposite sides thereof, each said body 1 subtending substantially less than 180 of angle, means to cause said bodies to emit electrons, and

a separate electrode disposed closely adjacent to each of said bodies, said electrodes each having a surficial area substantially equal to that of the respectively adjacent said body and being substantially equidistant in all parts of its surequal in area to the area of the respectively adjacent said electrode and substantially equidistant in all its parts from the corresponding parts of the surface of such electrode.

3. An electron dischargedevice, comprising a cathode support, strip electrodes on opposite sides of said support and closely adjacent thereto, and separate electron emissive bodies on said support respectively adjacent each said electrode, said electrodes being disposed with a substantially uniform distance between each surface element of said bodies and the corresponding opposed surface element of said electrodes, said distance being sufficiently short that the electron transit time from emissive body to'electrode is small compared to the period of a wave having a frequency in excess of Y500 megacycles.

tunable toga desired transfer frequency connecting said bodies to said frame at a. point sub stantially in electrical symmetry with respect to said frame, an oscillator operatively connected to produce inconjunction with thejinput frequency, the frequency to which said impedance is tuned, and output means operatively associated I V with said impedance;

7. An electrondischarge device, comprising an electron emissive cathode, two narrow strip anodes disposed adjacent to but spaced from each other parallel to and substantially equidistant from said'cathode on the same side of said cathode, a control electrodebetween each said anode and saidcathodafan'da focusing elec-' trode extending from adjacent one. of said anodes around said cathode but spaced therefrom' and to a position adjacent the other said anode."

8. An electron discharge device, comprising a cathode support, a narrow strip electrode dis-- posed adjacent thereto, and an electronemissive body on saidsupport, said body being disposed facing said electrode and having a surface area substantially equalto, that of said electrode, the

distances between all surface elements on-said.

body and the corresponding surface elements of said electrode being substantially equal. 1

9. An electron dischar'gedevice,comprising an electron-emissive cathode, two narrow strip anodes disposed adjacent to but spaced from a each other parallel toand substantially equi- 4. A circuit for high radio frequencies, com-j prising a discharge device as set forth in claim 1,

a resonant frame having two parallel conductive members connected together at their ends remote from said tube, means connecting the end of each of said members respectively to one,

of said electrodes, a tuning slider conductively connecting said members, input means connected to said slider, common means including an output impedance connecting said bodies to said slider and output leads connected to opposite terminals of said impedance.

5. A circuit for'high' radio frequencies, com prising a discharge device as set forthin claim 1,

aresonant frame having two parallel conductive distant from said cathode on the same side of; said cathode, a pluralityv of electrodes disposed between saidanodes and said cathode, and a focusing electrode extending from adjacent one: I

of said anodes around said cathode but spaced therefromand to aposition adjacent the other said anode I 10. An electron 1 discharge device, comprising 1 an electron-emissive cathode, two narrow strip members connected together at their ends ,re-

mote from said tube, means connecting the end of each of said members respectively to one of,"

said electrodes, resonating means connecting said members, means to apply input potential to said electrodes, means including an impedance" connecting said bodies to said frameat a point.

substantially in electrical symmetry with respect to said frame, and output leads connected to the terminals of said impedance,

6. A circuit for high radio frequencies, comprising a discharge device as set forth in claim 1,

' said cathode," an accelerating electrode, control a resonant frame having two parallel conductive members connected together attheir ends remote from said tube, means connecting the end, of; each of said members respectively to one; of said electrodes, resonating means, connecting saidanodesfdisposed adjacent to but :spaced from each other parallel to and substantially equidistant from said cathode on the same side of said cathode, control electrodes. and accelerating T electrodes successively disposed, between said' anodes and said cathode,and a focusing elec- I trode extending from adjacent one of said anodes around said cathode but spaced therefrom and tea position adjacent the other said anode.

A ll. An electron discharge device, comprising anelectron-emissive.:cathode, two narrow strip anodes disposed adjacent to but spaced from each other parallel toQand substantially equi-. distant from said cathodei on the" same side of electrodes, @anda farther accelerating electrode successively disposed between said cathode and said anodes, and a focusing electrode extending g from adjacent one of said anodes around'said cathode but spacedtherefrom and to a position adjacent the other said anode;

GEORGE E. PRAY.

SEBASTIAN moooBouo'.

. r 3 members, means to apply input potential to said f electrodes, means including an output impedance

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