AIR FORCE MIL-E-4957 A-1954 ENCLOSURE ELECTROMAGNETIC-SHIELDING DEMOUNTABLE PREFABRICATED FOR ELECTRONICS TEST PURPOSES《电子测试预制拆卸电磁屏蔽外壳》.pdf

《AIR FORCE MIL-E-4957 A-1954 ENCLOSURE ELECTROMAGNETIC-SHIELDING DEMOUNTABLE PREFABRICATED FOR ELECTRONICS TEST PURPOSES《电子测试预制拆卸电磁屏蔽外壳》.pdf》由会员分享，可在线阅读，更多相关《AIR FORCE MIL-E-4957 A-1954 ENCLOSURE ELECTROMAGNETIC-SHIELDING DEMOUNTABLE PREFABRICATED FOR ELECTRONICS TEST PURPOSES《电子测试预制拆卸电磁屏蔽外壳》.pdf（21页珍藏版）》请在麦多课文档分享上搜索。

1、Licensed by Information Handling ServicesH L-E - Li 7 5 7A 49 99Ob O243455 O WC-576 QQ-S-5Ii TP-W-SI1 TT-W-572 !G?sz MIL-C-71 m-c-3643 Ma-F-15733 MIEI4l81 MIL-P-66 MIL-W-6109 MfL-W-6llO JAN-P-100 Copper Flates, smsd Bars, Sheets, strips solder; soit, (Tln, Tin-Lead, aad Lead-SiZver) Prac tice Wood P

2、reservative; flecamiended Treating Wood Preservatve3 Uater-Repellent Connectors, “F for Raio Frequency Connectors, W for Radio Frequency Faters, Radio Interference Interfereme Linits, Testa and Design Cables Cables Requirements, Aircraft Electrical. ami Elecctronic Equipaent Plywood; Flat-Panel Wood

3、; Heo for ailn Drying Wood; Detendnation of Hoisture Content of Packaging and Packing for Overseas shipment - General aecification for Ha-Sn-129 HtL-STD-130 KtL-sm-220 Harking for shippent and Storage Method of insertiowhas Measurement for Identipicatian Harking of u. s. Military proparty Radio-Freq

4、uency Fiters (Copies of specifications, standsrda, drawfrigs, arad Publications required by contractors in connection wlth specific procurement fhnctions shaald be obtained from the prwa activity or as directed the contracting officei?.) 3. REQUIREMENTS 3.1 Component partsr- The shielding enclosure

5、shall consist of the required unite of one or more eachof the following parts aod acceesories: . Side panel, Connector panel. Floor-overhead panel Entrance panel. Flooring section. Shielded flooring strip (when Nailing blocks and accessolles (when required) Handbooks Of SrVIC iIIlo i i Licensed by I

6、nformation Handling Services3.3.1 Panel construction*- Panela ahell be .of wood frame, capper screened on both eidee, cm Srpe , and ln inch at each corner. The 1omen wire ahall be tightly dram about th6 frcpnework to i provide a unifom pacM of 1 iwh between screatM, i“ldiog d0rmre;unlees they are bo

7、nded to ecresnity by 8oldering. 3.3.2 Attenuation.- llu shielding efeetlmmss of a CcWletelY assembled pmlormre with pawerliii6 filter8 inetslled, rnd pater fed inta the enclosure, ehil be hmtured M deacrbed in paragraph 4.4, gd hata the plinliau attenuation ae WClfiOd threine t llengul. The !apwAfls

8、d. 3.3.1.3 Byihq.- None of the bolts, rachine scf.88 or mod screws wed in the . 3.3.3 Side aneh The Siae paisls dull be inches in width ODd 8 feet in will dapeiid opon the Isngth of the SMd- enclomre Licensed by Information Handling ServicesMIL-E-4757A Li7 7777706 0243460 4 T 3.3.4 Floor-overhead pa

9、nels.- The floor and overhead panels shall be 40 inches in width and 9 feet, 10 in ches in iength. of the shield-kg enclosure specified. The number required uill depend upon the width 3.3.5 Connector panel.- The connector .pans1 sl be interchangeable with a side panel as to size and bolting. dy one

10、shall be required for each shielding enclosure. in addition, it shai be equipped with pawerline inlets, powerline filters, and radio- frequency transmission-line feed-through connectors. side of the panel a sheet of hopper reenforcing of sufficient thickness and width to support six power entranoe f

11、ittings, four poiwerline filters, (with space for mounting two additional filters) and five radio-frequency tiranamission-lhe feed-through connectors. The copper reenforcing sheets shall be installed upon the connector panel in such manner as to withstand contimid insertion and removal of coaxial ca

12、bles, without damage to the connector panel material or deformation of the copper sheets. plates shaU be smooth and the outer edges slightly beveled With no sharp or rough edges exposed. Soldering of the plates to the shielding material shall be continuous about the entire periphery of the plate, an

13、d all soidering ahall be finished mmthly in order that no sharp or jagged edges or tips are -4. The powerline inlets shall be meallic waveguides, threeAfourths of an inch in diaiaeter, soldered to both copper reenforcing plates. radio-frequency transmission-line feed-throug connectors of the followi

14、ng types numbers: It shall have mounted upon each The copper sheets or 3.3.5.1 R-f connectors.- pon the copper reenforcing phtes shall be mounted five (a) mo type nNn assemblies. (The receptacles on each end of these asskmblies shall be siaiil- to type UG58A/U receptacles. ) One UO-loa, they will at

15、ltolaaccilly asaume a vertical. position and not extend over the edge of the entrance pidsd With WO dw-tp locke, The locke shall be iaatslled ia sach BBrmbf. that When not 3.3.6.1.2 2terfaces.- Two sets of dtipie-point, apring-loadd contact inter- 3.3.6.1.3 Other details.- Tbe hinged pariel ahall lp

16、 prodded With 0.125-inch corntm. 3.3,6.2 Reenorcement.- be sill ckidered to be the top an botton horiaoatal Licensed by Information Handling Services- MIL-E-495 I i .- Plywoo and teiapered-piasonite flooring sections shal be constructed 3*3.7 - as v sin e sections of safficient sise to cover each fl

17、oor-shielding panel. Each section shall be provideci with recessed pd-rings at each end to insert fingers for removal and installation. placed in position inside the assembled shielding enclosure they will form a complete covering of the floor panels nithminimupi space between. When in$h.led, the se

18、ctions shaU be even with the bottom supp8ce of the.entrance-panel aperture. be made to insure that the installation ofathe flooring sections do not damage the floor panels in any way. The sections shall be of such size-and fit that when Provisions shall 3.3.7.1 exceed 2 inches. Thickness.- The thick

19、ness of the completed flooring assembly shall not 3.3.7.2 Strength.- The flooring sections shal be reenforced, as necessary, to provide a deckim-11 withstand a distributed floor loading of 1% pounds per square foot without damage or deformation. lined with 2 layers of screen wire and fastened to bot

20、h adjacent panels by means of wood screws spaced 1 foot apart and provided with flat washers, shall be provided by the contractor in a sufficient number to cover the entire 1engths.of the grooves in the floor panels, unless the construction of the mau precludes the use of such strips, O 3.3.7.3 Shie

21、lded flooring strips.- Wood strips, 1-7/8 inch by 7/8 inch by 2 feet, I 3.3.8 Nailing blocks and accessores.- Slotted dovetail nailing blocks shall. be fabricated of wood, of such size that will press-fit between extended sections of the side panels on the-inside of the enclosure. -When installed, t

22、he nailing blocks shall not protrude over the surface of adjcent shielding panels. for use in supporting electrical fixtures, charts, test equipmentleads and cables, wire clamps, lighting fixtures, and ot_ier such devices as necessary to install nithin the shielding enclosure. number to assure accom

23、modation of all reasonable requirements for their use, and as specified by the procuring activity, unless the construction of the room precludes the use of such blocks. These blocks shall be suitable The blocks l General.- The hndbok of service instructions shal meet such Iwquirements as the PrOCur-

24、iVity may specify and shall contain the following infonnation. 9 Licensed by Information Handling Services- -*-I - 3.5.2 The handbook of service instructions shall Wul of th. cowleta Jiielding enclosure. 3.5.7 Eech complete assembly shall contain Go handbooks of service instructiom a6 part of the pa

25、ckaged assembly. 3.5.4 !h handbook of service instructions shall describe the satisfactoq- instal- 3.6, Workmanshi Workmanship on U coaponerrtfl of the shielding enclosure, Including d- pa s and accessories shell be in accordance with accepted standard practices for similar type construction. Tolera

26、nces.- Dimensions and tolerances not specified shall be in accordance with best shoD Dractices. 3.6.1 3.6.2 Screw assemblies.- Assembly screws shall be tight. The word “tight“ meana that the screw cannot be appreciably tightened further without damage or injury to the screw threads and wood frame or

27、 metal parts being assembled. 3.6.3 Cleani - All components shall be thoroughly cleaned of metal chips and other foreign -+i materi manner, and t 4. e sur ace “ swrounding the soldered connections shall be free fran after final assembly. All burrs, protrusions, and sharp edges shall be removed. 3.6.

28、4 Solderi AU. soldering su be effected in a neat and worirmanlike spatterings and excessive solder. Acid or corrosive fluxes ahall not be employed. Tliere shell. be no evidence of “cold soldering.“ 4.1 Classification of tests.- The inspection and .testing of shielding enclosures ahaU. be classified

29、as follows: 10 Licensed by Information Handling ServicesMIL-E4957A( Aso) (a) Preproduction tests: Preproduction tests are those tests perfonned on samples representative of the production of the item after the auard of contract, to deternine that the production meets the requirements of this specifi

30、cation. (b) Acceptance test+ Acceptance tests are those tests performed on indivua lots which have been suhuitte for acceptance. 4.2 Preproduction tests.- 4.2.1 Sampling instructions.- The Preproduction test sample shall consist of one complete enclosure (assembled) which shall be tested at the cont

31、ractors plant under the supervision of the procuring activity to determine compliance with dl the require- ments of this specification. powerlhp eMrances instailed to simulate a stade installation. The enclosure to be tested shall have fourfiltered 4.2.2 Testa.- The Preproduction tests shall consist

32、 of all the tests of this specification, as bescribed under “Test methods,“ and aqy other tests deemed necessary to determine compli.axe With the requirements of this specification. 4.3 Acceptance testa.- The Acceptance tests shall consist of Examination of product and Sampling tests. 4.3.1 Examinat

33、ion of prodPct.- All component parts shaY be subjected to the following test as described under *l!estmethods“: (a) wamination of product. 4.3.2 Sampling tests.- One enclosure from each lot of 25 enclosures or fraction thereof shall be assembled and subjected to all the tests of this specification.

34、components used in assembiing the enclosure shall first have passed the Examination of product test. U 4.4 Test methods.- b.4.1 Examination of product.- Each fabricated component ana part shall be carefully examined to detelmine conformance with dimensiom?, materials, parts, workman- ship and, in th

35、e case of an assembled enclosure, all fittings, mechanical joints, and ease of operation of all moveable parts. 4.4.2 Measurement of attenuation of low impedance bgnetic) fields.- Attenuation of low impedance (mametic) fields shall b e measured as follows, usinn the test setuD described below a;id s

36、tep attenuator. A signai. generator may be used to calibrate the attenuator. - 4.4.2.1 Attenuator.- The attenuator A may be a 50- or 7T-Oh transmission-line, The attenuator shall be able to measure an insertion loss of over 70 db. 4.4.2.2 Detector.- me det If detector D shows no indication above Wie

37、 inherent background when-the 4.4.4 Heaaurement of attenuation of plane w.8.- Attenuation of plane waves Licensed by Information Handling ServicesLicensed by Information Handling Services- 72I“Es a, = 1I“ d3 2 INCHES DISTANCE SHOULD BE AS ORGAT ASbwsSI AND LIMITED ONLY BY Tflg OUTPUT OF Se Hm, ILUJA

38、YS HOLD HC8E TfIAN TWO TIMES THE . m m A D le FIGm 7. TWO INCHES IS THE MINIMUM-VALUE. R2 IS POSITIONED A“EE DBTECTQ D, IN aUlm To MINIMIZE ME EFFECT OF REFLECTIONS* INSIDE mE ENcu)SuRE; AMI OR- FOR HAlfIMuM INDICATION ON HOT LECC TiAN 2 INCIIES, AND NOT WRJf 2lUN 8 INCHES. R3 IS wSITION%D A“ERE OUT

39、SIDE THE ENCLOSURE AM) FOR MAXMUM INDICATION OH DETECTOR D, IN ORDER TO MINIMfZE THE ETFECT OF REEZECTIONS. SHAI;L NEVER BE CLOSER THAN 2 INCHES TO , Se, IN ORDh TO THE ENTIRE REGION, FROM 2 INCHES TO 8 INCHES SHALL BE EXPLORED FOR HAXMUH INDICATION. R PlBVE?lT CAPACITP COUPLING. OUTER AND INNER SCR

40、EENS, RESPECTIVELY. TRANF4ISSION-LINE COWNECMR. SIbNAL SOURCE, To OBTAIN ADEQUATE OUTHIT AT THE TEST FREQUENCY. REcEIvIm ANTENNA, MAY BE SIMILAR To % USED ONTJY IF NEcgssbELp. SHIELDED TRANSMISSION-LINE; CIIBLES. AmATOR, CALIBRATED AT “E -mOF TEST. DBECTOR OF ADEQUATE SENSITIVITY, TUNED TO TI1E FREQ

41、UENCY Op TEST. USIZD ONLY A3 AN WAL RETERENCE INDICATOR. AS SHORT A9 WSSIBLF, AND Licensed by Information Handling Servicesb.4.4.1 Attenuator.- The attenuator used may be a 50- or 72-ohm trsnsmission- line, constant Input-iaipedance, step attenuator. may be connected in series. A signal generator ma

42、y be used to calibrate this attenuator. This attenuator shall be capable of measuring insertion losses in qcess of 100 db. 4.4.4.2 Detector.- The detector may be a receiver, such a8 the AN/APR-h,. . AN/uRH-28, AN/mG-27, or a field-strength meter, such as the TS-S87/U or the AN/URM-17. Detectors whic

43、h cannot readily give peak indications may be used wlth an oscilloscope connected to their output. if separate units are avafiate, they 4.4.4.3 Signal source.- 4.4.4.3.1 Signal sowe S may be a signal generator or power ogcillator of sufficient cw, mcw, or pulsed m,output. The tennination of cable C

44、may be used when necessary. used instead of attenuator A, to obtain an equivalent ratio of %/E2 for the calculation of the attermatba of the encloFe using the detector D at t e same reference level. In this ame, precaution may have to be taken to guard against leakage at the detector, Re11i.p signal

45、 generator, or an AN/APT-S radar transmitter. An oscillator, tuned to the frequency of test mey be constructed, using a high-voltage plate supply and then pulsed 4.4.4.3.2 if the siga generator has a reliable output atteuuator, it may be k.b.4.3.3 The signal source may be an AN/ARC-27 transmitter, a

46、 Mgh-frequency A signal source may be constructed as shown in figure 8. , to obtain high-peak power. 4.4.4.4 Measurement of db attenuation.- 4.4.4.4.1 db setting of atternator A necessary to obtain the same reference reading level in detector D when the receiving antenna is switched from position R2

47、 to R3, without changing the position of Ri. . db is also essentially equal to 20 log.(base 10) wE2, where E1/E2 are the voltages induced in R3 a4 R2, respectively.) The attenuation of the enclosure in db is equal to the increase A. I h.b.4.4.4 if this attenuation i I 111 i i. Licensed by Informatio

48、n Handling Services_ MIL-E-4957A Y7 W 9949906 0243473 2 m=I+495M( As) *fl ELL I 1 42 INCHES I cB+ c B- c llov c AC DIPOLE AN“A. EACH ROD 1/16-INCH DIA. 7 FEEX LONG, HORIZONTAL. I/h-INCH SOLID COPPER RODS, ONE-FOURTH OF AN INCH APART, 2 INCHES FROM INSULATING BOARD. PORCELAIN INSULATORS, 2 INCHES HIG

49、H. CHOKES, 30 TURNS NO, 18 WIRE, l/Lr-INCH DIA, SUSPENDED IN AIRI CHOKE, 40 TURNS No. 28 WIRE, l/h-INCH DIA, WSPENDED IN AiRe 15,000 OHMS, 10 WATT. MISE CLIPS. INSULATING BOARD0 FILAHFdT TRANSFORMER 242 VOLT SECONDARY, CENTER TAWED, OR TWO 1-1/2 VOLT DRY CELLS WITH PR0pE;R LIMITING RESISTOR. VACWH TUBE W.E. 316A, Ep 49V, Ip 80 MA, Ef 2.0V9 If 3.65 AMP, Ig 12 MA. OUTPUT 7.5 WATTS. SUPPLY; OR 1,OOOV AC, RMS, 604YCLES FROM HIGH VOLTAGE TRANSFOm. PLATE VOLTAGE, 450V DC FROM ANY DRY CELLS OR RECIFIED A-C p(TwE