Патент USA US2406405код для вставки
Aug. 27, 1946. ` F, L, sALlsBURy ‘ 2,406,405 COAXIAL coNDENsER CRYSTAL AND METHOD oF MAKING SAME Filed May 19, 1941 7 MMW"""""""""" .......... ,f \.\ 44 25 g1g» INVENTOR. FRI-:Demers L . _sALlsBuRY . 1MM/M HIS ATTORNEY .5 Patented Aug. 27, 1946 2,406,405 UNITED STATES PATENT OFFICE 2,406,405 COAXIAL CONDENSER CRYSTAL AND METHOD OF MAKING SAME Frederick L. Salisbury, Hempstead Gardens, N. Y., assignor to Sperry Gyroscope Company, Inc., Brooklyn, N. Y., a corporation of New York Application May 19, 1941, Serial No. 394,239 8 Claims. (C1. Z50-31) 1 This invention relates to mountings for crystals apparent in the following speciñcation and draw such as are used for rectiñers or detectors, and ing, wherein, to a method for making these mountings. In the Well-known “cat’s-whisker” type of crystal mounting, the crystal is held in a conduct ing body which forms one terminal, and the sec ond terminal, or “cat’s-whisker” is held against a sensitive spot on the crystal. It is not only Fig. 1 is a section along the axis or" a complete crystal mounting and adaptor for concentric diiiicult to ñnd a sensitive spot on the crystal suitable for use, but it has been exceedingly difû cult or impossible in devices heretofore used to keep the “cat’s-whisker” in contact with such a l transmission lines; Fig. 2 is an enlarged fragmentary vieW of the crystal engaging tip of the “cat’s-whisker”; Fig. 3 shows the testing and assembling device for the crystal mounting of Fig. 1; and Figs. 4 to 6 diagrammatically show cathode ray 10 tube indications under various conditions to ex plain the testing of the crystal in the device of spot. Mechanical vibration, temperature varia Fig. 3. i tions, change in humidity of surrounding atmos Fig. 1 shows the completely assembled crystal phere, oxidation of Wire, etc., all tend to impair 15 rectifier or detector. This is made of a holder I, this contact and hence the eñìciency and eilec of brass or any other conductive material, pro vided With a recess 3 of suitable diameter. A small outlet or bleeder hole 5 is provided from tiveness of the crystal. It is an object of the present invention to pro vide _an improved crystal mounting which is stable the >outside of holder I to the bottom of recess 3. in operation and ln which the contact between 20 Apiece of crystal 'i having unidirectional con crystal and “cat’s-whisker” is substantially not ducting properties, such as Zincite, silicon, Car alîected by vibration, moisture, temperature or borundum, galeria, hertzite, molybdenum, etc., is other iniluences to which crystal contacts have forced into recess 3 so as to make good electrical heretofore been subject. and mechanical contact with the inner Walls of It is another object of this invention to provide 25 holder I. Before placing the crystal in position an improved crystal mounting which is sealed it may be tested, in the manner to b-e described from the atmosphere and is mechanically secure beloW, to insure that a sensitive portion is placed against vibration, thus being suitable for use facing the opening of recess 3.l under conditions of change in temperature, hu The holder I and crystal 'l are then heated midity, pressure and vibration, as, for example, 30 together by any Suitable means, as by being placed are found on airplanes. on the surface of an electric iron. When hot, some thermoplastic substance 3' having good di It is still another object to provide a crystal mounting in which the “cat’s-Whisker” is perma nently sealed in place by a thermoplastic dielec electric qualities at ultra-high frequencies of the order of 109 cycles per second, such as Various tric material having high e?liciency at ultra high frequencies, thereby permitting the crystal to be satisfactorily used at such high frequencies. types of materials known as polystyrene, is placed It is a further object of this invention to pro vide a, novel method of manufacturing a, mounted properties suited to the intended use of the crys Within the recess 3. It should be noted here that any thermoplastic material having electrical tal may be used. When properly heated, the crystal unit which makes it possible to manufac 40 thermoplastic material becomes semi-fluid and ture such units in extremely small size and of flows around the crystal 1. All air is forced out high emciency, such as are necessary for use with the bleeder hole 5 and the thermoplastic mate ultra-high frequency circuits._, rial thoroughly wets and surrounds the exposed A further object is to provide a useful mounting surface of crystal l and ñlls holder l so that, for a crystal which is easily adapted to be con 45 after cooling, the crystal l is kept completely nected in a concentric transmission line circuit. separated from and independent of all atmos Another object is to provide a useful crystal pheric influences. While the thermoplastic material is still plastic, the “cat’s-Whisker” conductor 9 is placed roughly mounting for use with a concentric transmission line system which has a distributed by-pass ca pacitance built into the crystal mounting. Y Still another object is to provide a mounting for a crystal inside a section of concentric trans 50 concentrically Within recess 3. The conductor 9 is shown in Fig. 2 as made of metal tubing, flat tened at one end, which is formed with an oir mission line, whereby the crystal is electrically shielded from extraneous electric ñelds. v Further objects and advantageswill become .55 set sharpened tip Il. The particular shape of the “cat’s-Whisker” 9 is convenient for appli cant’s method of manufacture, as will be ap~ 2,406,405 parent, but any type of wire or other small ductor may be used. The entire unit as thus far assembled is placed in proper position on a cooling mounting base I3 (Fig. 3). This position con then and may be marked by any suitable means, such as by a recess as at I5 or a holding jig may be used. The 4 capacitance whose electrodes are holder I and body 35. The capacitance acts as a distributed bypass condenser for the waves rectified by the crystal 1. Furthermore, the construction is such that all parts of the crystal circuit are fully shielded, since everything is within body 35 which acts as a continuation of the outer conductor 44 unit is thereby held immediately under the of transmission line 39. 'The output transmis roughly concentric with an adjusting member I1 sion line 39 may be replaced by an ordinary which is adjustably held in a split clamp I9 and ' > fastened therein by some means such as a screw 2l. Member I1 has a reduced portion 23 which fits snugly into the hollow portion of “cat’s Whisker” conductor 9, which is thus held by member I1 roughly in a position coaxial 'with recess 3. Member I1 is then manipulated as by turning with clamp I9 loosened until `the “c'at’s Whisker” 9 is in contact with an optimum sensi tive spot on crystal 1, as indicated on 'the test device to be described below. The finding of the sensitive spot is aided by the ofi-setting >of por tion II of conductor 9, as this permits ra large part `of the outward facing surface of crystal 'I to ‘be explored. After lsuch a sensitive 'spot has been found, clamp I9 is fastened to hold member I1 in position while »the thermoplastic material cools and hardens. The cooling is expedited `by running cooling water »through suitable passage means in metal base I3, as bypipe 2-5. The “cat’s Whisker” '9 is thereby cast rigidly i-nto the proper ; position. If no sensitive ‘spot 4is found before the thermoplastic -materia-l hardens, the unit is re moved and reheated and the process is repeated. By the above method I >.secure a fixed crystal unit with “cat’s-whiske'r” 9 firmly and perma nently secured in piace. 'The contact between crystal 1 and “cat’s-whisker” 9 is >‘completely sealed oit from the atmosphere, and good perma nent >contact is `secured to the crystal 1. The unit so Aobtained is found to be vextremely stable in its characteristics `over wide 'changes of con~ 'dit-ions of use. It is especially iresist-ant to vibra tion, and is therefore very useful‘on 4‘airplane in stallations. After cooling, -the -base ‘of crystal ‘holder `I is placed in an adjustably eccentric "chuck Aof »a lathe, while conductor 9, now a fixed part of the unit, is used to center the unit -in the lathe. shielded cable if high frequency emciency is not necessary for the rectiñed currents. The above is, of course, only one way of adapt ing the crystal holder I of the invention to a particular use. yThe method of mounting the crystal 1 above fdescribed may obviously be used to mount this crystal in an opening in any metal lic body whatsoever, and is not restricted to the particular type shown. Successful crystal mountings have been made in the end of a 10-32 screw, and it is possible to make a mounting by the method `»described in an opening as -small as .060 inch ldeep and ».1050 »inch wide. The method of testing the -c‘rysta‘ïl for to Adeter mine when the “catfs-whisker” -S -is in «contact with a suitable sensitive spot will vnow be ex plained. Referring to Fig. 3, it will be seen ¿that clamp i9 is insulated from base ~I3 and bracket 45 ‘as by an insulating block 41. Conductor 9 which is one termina-i fof crystal '1, «is connected as through members I1 Aand clamp II9 and by mea-ns of a conductor 59, -`to a »resistor '49 which is connected in turn to one terminal of the sec ondary winding -of stepdown `trans-former ~5I en ergized from Lan A. (C. supply »line 53. The ïholder I, which «acts as the other terminal of y'the ~cry’s‘ tal 1, is connected, for example, through base I3 and bracket 45 and by means fofconduotor 6I to the other side of the secondary winding -of transformer 5I, 'which fis 4designed to .have `suit able seccndary -voltage chosen so as 'to Yprevent any damage fto the crystal 1. Resistor 49 pre vents excessive current from flowing in <the crys tal circuit. A standard~oscillograph155 is ener gized from the same supply line 53 through' -its usual power supply >¿51. AOne pair 'of »deflecting plates of oscillograph 35:5, such Aas 'the 4horizontal deflectin'g plates, is connected across "resistor 49. The fot-‘her pair, such »as 'the vertical defle'cting The “outside of Vholder lI is no'w turned Jdown lon pla-tes, is »connected across conductors -59 ¿and ïGI , the ‘lathe to roughly Acylindrical Vshape but having which lare connected tothe crystal A1,1s'o îthat'this pair` is energized by the voltage across crystal 1. lThe usual amplifiers may be used »for-amplifying `a'slight ltaper l23, and it is ‘made concentric with member 9. vIf conductor 9 vdid vnot lharden ‘into ~place exactly -coaXia-l with recess ‘3, the walls 'of the voltages applied to ‘the fdeiiecting plates, lf desired. Ii conductors 59 and ïEI ~were ‘open rcircuited, the ‘voltage across resistor >49 would be Zero and that across conductors 59, 6I would be maximum. ~Accordinglly, fa trace ‘163 such as -that shown in Fig. 4 would be obtained. If `conductors V59 and :6I were short-circuit‘ed, 'their potential conductor ‘9. An insulating tape having 'good 60 diiîerence would be '-Zero, while vvthe voltageßacross resistor 49 ‘would be maximum so that ïthe trace Adielectric properties at the operating frequencies -65 `'shown in Fig. 5 would »be obtained. It thus is now wound Aon the tapered portion, `as at `33, will be seen that'the cathode «ray osciîlïlo‘g-raph and the wound unit 4is then forced into ‘a `mating holder I will `not be of uniform thickness, but this is immaterial. The ‘unit is Vnow placed in ‘a tapered 'chuck which ñts the taper formed on the unit, and a tip 3| is formed by turning down the end of the unit. This tip 3‘I is `also formed concentric with 'the outside of the 'unit a'nd'with trace indicates, byïitsf's'lo'pe, the :impedance of ¿the taper in body 35 which has `standard >clamp adaptors 31 at ‘each end whereby the 'completed 65 circuit connected to v'conductors ì59, 31. 'A verti cal ‘trace 63, having 'infinite slope, indicates 'in unit may be connected to concentric transmis» Afinite impedance 'Kopen-circuit). A 'horizontal sion lines such as 38, 39. With Asuoli connection, trace 65, having 'zero slope, indicates zero im =conductor ‘9 'may slide over `the 'inner vconductor pedance (short-circuit). Since Ahorizontal :de "40 of transmission line v38, as `at 4l, and tip 3l may slide into the inner ‘conductor 42 of the 70 iiection is proportioned 'to current through ~the 'crystal 1, and vertical deflection >is proportional other transmission Aline 39,'asat 43. It is obvious to voltage across crystal 1, ‘the slope «o'f >the trace, that either or both conductor 9 'and tip 3`I could which is therefore vproportional "to voltage -`di“ slide over or lunder its corresponding connecting vided by current, >will Valways v"indicate the true member. The tape 33 forms'the dielectric of a'distributed 75 impedance of the crystal `‘|. A‘theoreticallyfper 2,406,405 6 fect crystal should be a perfect short-circuit for half-cycles of applied A. C. of one polarity, and a perfect open-circuit for half -cycles of the other polarity, giving a trace 61 as shown in dotted lines in Fig. 6. Such a perfect trace 61 is rarely obtained. A good trace 69 often realized is shown in full lines in Fig. 6. Hence, in exploring th‘e said tubular member form output terminals, and iier or detector having the desirable qualities set ’ a conducting member serving as a terminal for said body and tubular member form a by-pass condenser. 4. A device as claimed in claim 3 further com prising adapting means for connecting said in put terminals to a concentric transmission line, and for connecting said output terminals to a crystal 'l with the “cat’s-Whisker” 9, the latter shielded line. is manipulated until a trace at least as good as 5. A shielded crystal mounting comprising a 69 is obtained, and the “cat’s Whisker” 9 is then 10 conducting body having a recess therein, an uni held in position until the thermoplastic material directionally conducting crystal seated within sets, thereby yielding a permanent crystal recti the recess in electrical contact with said body, forth above. said crystal, and insulating material holding said Although the invention has been illustrated by 15 conductor in electrical contact with said crystal, one embodiment, it is evident that many different a tubular member placed outside said conducting embodiments of the invention could be made body and means electrically insulating said mem without departing from the scope thereof. It is ber from said bodyÍ whereby said conducting therefore intended that the above description member and said tubular member form input ter shall be interpreted as illustrative only, and not 20 minals to said crystal, said conducting body and in a limiting sense. said tubular member form output terminals, and Having described my invention, what I claim said body and said tubular member form a by and desire to secure by Letters Patent is: pass condenser. ' l. A concentric transmission line mounting for 6. In a mounting for a unidirectional conduct a crystal comprising a shielding outer conductor, 25 ing crystal, a body of electrically conducting ma an inner conducting body insulated from said terial formed with a recess in which said crystal outer conductor and having a cavity therein, a is seated in intimate contact with said body, a crystal ñtting snugly into the cavity so as to conductor extending into said recess into Contact make intimate contact with' the Walls thereof, with a sensitive area of said crystal, solidiiied in a Wire serving as a terminal for said crystal, and 30 sulating means contained within said recess `for insulating material holding said wire in electri retaining said crystal therein and surrounding cal contact with said crystal. and retaining said conductor in contact with said 2. The method of making a mounted crystal crystal within said recess, and substantiallyrax which comprises the steps of forming a recess in ially aligned connector terminals for said body a body of electrically conductive material, form 35 and said conductor respectively projecting 'from ing a bleeder hole at the bottom of said recess, opposite ends of said body. forcing a unidirectionally conducting crystal into 7. In a mounting for a unidirectional conduct said recess to make intimate contact with the ing crystal, a member of electrically conducting Walls of said recess, placing a thermoplastic sub material formed rwith a recess in which said crys stance in said recess, heating said body and sub 40 tal is seated in intimate contact with said mem stance above the temperature at which' said sub ber, a conductor extending into said recess into stance becomes plastic, whereby said substance contact With a sensitive area of said crystal, Will iiow around said crystal and make intimate solidiñed insulating means retaining said crys contact therewith, inserting a conductor into said tal in said recess and retaining said conductor` plastic substance to make contact with said crys in contact with said crystal, a second member of tal, exploring the surface of said crystal until said conducting material extending about said ñrst conductor is in a position making contact with member, and electrical insulation between said a sensitive spot of said crystal, holding said con members. ductor in said position and simultaneously cool 8. A mounting for a unidirectional conducting ing said thermoplastic material to below its plas- f crystal comprising a body of electrically conduct tic temperature, whereby it solidiiies and holds ing material formed with a recess in which said said conductor permanently in said position. crystal is disposed in intimate contact with said 3. A shielded crystal mounting comprising a body, a conductor in contact with a sensitive area roughly cylindrical body having a recess substan of said crystal, insulating means securing said tially concentric thereof, a unidirectionally con crystal to the walls of said recess and retaining ducting crystal pressed into said recess, a wire said conductor in contact with said crystal, and held in contact with said crystal roughly concen substantially axially aligned connector terminals tric of said body and a tubular member placed for said body and said conductor respectively outside said body and insulated therefrom, projecting from opposite ends of said body. whereby said wire and said ltubular member form input terminals to said crystal, said body and FREDERICK L. SALISBURY.