1、MIL-A-28768B 57 = 7797906 0033253 L b-Ob-* O -*$ a a MILITARY SPEC IF I CAT I ON ANTENNAS , FIXED HIGH FREQUENCY , GENERAL SPECIFICATION FOR MIL-A-28768B( EC) 3 April 1984 SUPERSEDING 1 June 1973 . MIL-A-28768A This specification is approved for use by the Naval Electronic Systems Command, Departmen
2、t of the Navy, and is available for use by all Departments and Agencies of the Department of Defense. 1. SCOPE. 1.1 SCO e. This specification covers the general requirements for fixed, shore-based , high frequency . General Specification For Insulator, Strain, Rigging Paint, High Zinc And Dust Conte
3、nt, Galvanizing Repair Thread Compound Antiseize Zinc Dust-Petrolatum Transfornier I Impedance Matching, Balanced To Unbalanced (BALUN) Poles, Structural Wooden, For High Frequency (HF) Antennas Transformer , Impedance Matching (Balun) , Receive Only Sealing Compound Environmental , For Aircraft Sur
4、f aces Connectors , Coaxial, Radio Frequency, General Specification For Inspection System Requirements Adhesive-Sealants, Silicone, RTV, General-Purpose (For Electrical And Mechanical Sealing) Coating Aluminum, Ion Vapor Deposited General Specifi- Sampling Procedures And Tables For Inspection By Att
5、ributes Definitions Of And Basic Requirements For Enclosures For Electric And Electronic Equipment Quality Assurance Terms And Definitions Standard General Requirements For Electronic Equ i pmen t Electromagnetic Emission And Susceptibility Requirements For The Control Of Electromagnetic Interferenc
6、e Electromagnetic Interference Characteristics, Measurement Of Environmental Test Methods And Engineering Guidelines Parts Control Program Standard General Purpose Electronic Test Equipment Grounding, Bonding And Shielding For Electronic Equipments And Facilities Licensed by Information Handling Ser
7、vicesMIL-A-28768B 57 7777906 0033255 5 MIL-A-28768B( EC) 2.1.2 Other Government publ ications. PUBLICATIONS The following other Government publ ications form a part of this speckfication to the extent specified herein. NAVAL FACILITIES ENGINEERING COWMAND (NAVFAC) NAVFAC DM-2.2 NAVFAC DM-7.2 Design
8、Manual , Structural Engineering Loads Design Manual , Foundations And Earth Structures FEDERAL AV I ATION ADMINISTRATION (FAA) FAA Adv i sory Circular Obstruction Marking And Lighting 70/7460-1 . (Copies of specif ications, standards, handbooks, and publ ications required by manufacturers in connect
9、ion with specific acquisi tion functions should be obtained from the contracting activity or as directed by the contracting officer.) extent specified herein. the issue listed in the current DoDISS and the supplement thereto, if applicable. 2.2 Other publications. The following documents form a part
10、 of this specification to the The issues of the documents which are indicated as DoD adopted shall be AMERICAN INSTITUTE OF STEEL CONSTRUCTION (AISC) Manual Of Steel Construction (latest edition) (Application for copies should be addressed to the Pnerican Institute of Steel Construction, Inc., 400 N
11、 Michigan Avenue, Chicago, IL 60611.) THE ALUMINUM ASSOCIATION (AA) Aluminum Construction Manual, Aluminum Association Standard “Specification For Aluminurn Structures“ (latest edition) (Application for copies should be addressed to The Aluminum Association, 818 Connecticut Avenue, NW, Washington, D
12、C 20006.) AJlERICAN WELD I NG SOC I ETY ( AWS) AWS C2.2 AblS D1.l Recommended Practice For Aluminum and Zinc For-Protection Of Iron And Steel Structural Welding Code (Application for copies should be addressed to American Welding Society Inc. , 550 Northwest NATIONAL FOREST PRODUCTS ASSOCIATION (NFO
13、RP) I Jeune Road, Mimi, FL 33126.) Natjonal Design Specifications For Stress-Grade Lumber And Its Fastenings (Application for copies should be addressed to National Forest Products Association, Forest Industries Building, 1619 Massachusetts. Avenue, NW, Washington, DC 20036.) AbIERICAN NATIONAL STAN
14、DARDS INSTITUTE (ANSI) ANSI C29.1 ANSI C29.2 ANSI C29.3 ANSI C29.4 ANSI C29.5 and C29.5a ANSI C29.6 and C29.6a ANSI C29.7 and C29.7a ANSI C29.8 ANSI-C29 -9 Electrical Power Insulators, Test Methods Wet-Porcelain Insulators (Suspension Type) Wet-Porcelain Insulators (Spool Type) Wet-Process Porcelain
15、 Insulators (Strain Type) Wet-Process Porcelain Insulators (Low- And Medium- Voltage Pin Type) Including Supplement Wet-Process Porcelain Insulators High-Vol tage Pin Type) Including Supplement Wet-Process Porcela in Insu1 ators (H lgh-Vol tage Line-Post Type) Including Supplement Wet-Process Porcel
16、ain Insulators (Apparatus, Cap And Pin Type) Wet-Process Porcelain Insulators (Apparatus, Post TYPE) (Application for copies should be addressed to the American National Standards Institute, 1430 Broadway, New York, NY 10018.) Licensed by Information Handling Services_ MIL-A-28768B 57 7777706 003325
17、6 7 9 MIL-A-Z8768B( EC) AMERICAN SOCIETY FOR TESTING AND MATERIALS (ASTM) A123 A153 A194 A325 A475 82 8415 B4 16 D2303-64T Zinc (Hot -Galvanized) St andard Specification For Coatings On Products Fabricated From Rolled. Pressed And Forged Steel Shapes, Plates, Bars And Strip Zinc Coating (Hot Dip) On
18、 Iron And Steel Hardware Nuts, Carbon And Alloy Steel, For Bolts For High Pressure And High-Temperature Service Joints, Structural Steel High Strength Bolts For Wire Strand, Zinc Coated Steel Wire, Copper, Medium Hard Drawn Hard-Drawn Aluminum-Clad Steel Wire Concentric Lay Stranded Aluminum Clad St
19、eel Conductors Test For Liquid - Contaminant, Inclined Plane Tracking And Erosion Of Insulating Materials (Application for copies should be addressed to the American Society for Testing and Materials, NATIONAL FIRE PROTECTICN ASSOCIATION (NFPA) 1916 Race Street I Philadelphia, PA 19103.) NFPA 70-198
20、1 Nat ional Electrical Code . At 1 antic Avenue , Boston I MA 02210 .) (Application for copies should be addressed to the National Fire Protection Association, 470 (Industry association specifications and standards are generally available for reference from 2.3 Order of precedence. 3. REQUIREMENTS 3
21、.1 Detail specifications. The individual antenna requirements shall be as specified herein libraries. They are also distributed among technical groups and using Federal agencies.) In the event of a conflict between the text of this specification and the references cited herein, the text of this spec
22、ification shall take precedence. and in accwicable detail specification. the requirements of this specification and the detail specification, the latter shall govern. herein. tion (see 4.3 and 6.3). in 3.3.1 through 3.3.5. Parts and materials which are used but which are not specified in 3.3.1 throu
23、gh 3.3.8 shall be in accordance with MIL-E-16400. Parts and materials which are not permitted by MIL-E-16400 shall not be used. Derating and interchangeability shall be in accordance with MIL-E-16400. Equipment performance shall not be dependent on the selection of special values for individual part
24、s. IJsed or damaged parts or materials shall not be used. All materials shall be fungus inert in accordance with MIL-E-16400. In the event of any conflict between 3.2 General. The antenna shall be in accordance with MIL-E-16400, to the extent specified 3.2.1 First article. When specified, a sample s
25、hall be subjected to first article inspec- 3.3 Parts and materials. Parts nd materials shall conform to the requirements specified 3.3.1 Towers. 3.3.1.1 Structural steel. All structural steel shall conform to the specifications Towers shall be as specified in 3.3.1.1 through 3.3.1.2. listed under th
26、e AISC Specification for the Design. Fabrication, and Erection of Structural Steel for Buildings, unless otherwise specified herein. to 3.5.2.1, 3.5.2.3, or shop welded in accordance with AWS D1.l. hardware conforming to 3.5.2.3 shall be installed by the turn-of-the-nut method in accordance with Par
27、t 5, Specifications and Codes of the Manual of Steel Construction. 3.3.1.1.1 Steel connections. All steel connections shall be made with hardware conforming Structural connections made with 4 Licensed by Information Handling ServicesMIL-A-2B7bBB 57 7777706 0033257 7 W MIL-A-28768B( EC) 3.3.1.2 Struc
28、tural aluminum. Structural aluminum shall conform to the specif icat ions 3.3.2 Wooden poles. listed under the Aluminum Construction Manual, Specification for Aluminum Structures.“ (see 3.1) shall conform to MIL-P-28766. shall be supplied in single, continuous lengths. completely encased in concrete
29、 and embedded in the ground. . from at least 76.2 millimeters (mm)(3 in.) above ground level to not less than 52.4 mm (6 in.) below the bottom of the pole. 3.3.3 Cables. 3.3.3.1 Steel cables. Steel cables shall be stranded and shall conform to the requirements Wooden poles, when specified in the app
30、licable detail specification Splices in wooden poles are not permitted. All poles Poles shall be designed to hsve pole bases 6 The concrete encasement shall extend Cables shall be as specified in 3.3.3.1 through 3.3.3.5 of ASTM A475. c 3.3.3.2 Aluminum clad steel wire. Aluminum clad steel wire shall
31、 conform to ASTM B415. Aluminum clad steel cable shall conform to ASTM 8416. 3.3.3.3 Nonmetallic guys. Nonmetallic materials for use as tower and pole support guys shall be limited to materials having physical , mechanical , and electrical properties specified in 3.3.3.3.1 through 3.3.3.3.5. but in
32、no case shall the nominal diameter be less than 9.53 mm (0.375 in.). 3.3.3.3.1 Dimensions. The nominal diameter of the guy shall be as specified by the designer, 3.3.3.3.2 Breaking strength in tension. The minimum breaking strength in tension of the rods with end fittings attached shall be: Rod diam
33、eter mm (in.) Minimum breaking strength, kilograms (kg) (pounds (lbs) 9.53 (0.375) 12.70 (0.50) 15.88 (O .625) 19 .O5 (O .750) 25.4 (1.0) 5455 (12,000) 9091 (20 ,000) 13,636 (30,000) 18,182 (40,000) 29,545 (65,000) 3.3.3.3.3 Elon ation. 3.3.3.3.4 Wet stren th. The wet strength of the rod shall be no
34、t less than 90 percent of 3.3.3.3.5 Fatigue strength. The maximum elongation at one-third the minimum breaking strength shall be less th*nt of the length of the rod. the average breahh specified in 4.5.3.3. shall be not less that 80 percent of the average breaking strength of that size as specified
35、in 4.5.3.3. The fatigue strength of the rod, with end fittings installed, 3.3.3.3.6 Fittings and fitting attachments. The ends of the guys shall be terminated with galvanized steel wire rope sockets conforming to Type A and Type B, Finish 2 of RR-S-550 of size appropriate to the guy diameter. Cotter
36、 pins used with steel fittings shall be Class 302 or Class 304 corrosion-resistant steel conforming to QQ-S-763. to the guys and shall be capable of developing 100 percent of the rated minimum breaking strength of the guy. 100 percent of the rated minimum breaking strength of the guy when tested in
37、accordance with 4.5.3.1. foot (ft) of length measured by a 500 volt (V) megger under standard room conditions. 3.3.3.4 Cable tolerances. Tolerances on cable elements (see 6.4.3) of the antenna system, including catenaries and radiating elements, both for the lengths of the cables and for the locatio
38、ns of the fittings and connections along the cable, shall not exceed the values specified herein but may be less if dimensional stability of the antenna system requires it. Tolerances shall be re- ferenced to the cable end points, shall be noncumulative, and shall be measured under a minimum of 10 p
39、ercent prestress of maximum design load. The end fittings shall be affixed 3.3.3.3.7 End grips. 3.3.3.3.8 Electrical resistance. Field installable end grips, if utilized, shall be capable of developing The guys shall have a minimum resistance of 10 megaohms per Licensed by Information Handling Servi
40、ces- ._ MIL-A-28768B 57 W 777770b 0033258 O 9 I 3.3.6.2.1 Electrical and electronic items. For nonstandard parts purposesI these parts include but are not limited to: RF insulators, electronic components such as semiconducters, resistors, capacitors, inductors, transformers , electrical connectors,
41、cables I and similar items; components contained in a matching unit; components contained in the obstruction lighting system; and any similar parts which are basically of an electrical , electromechanical or electronic (as contrasted to a structural) nature. MIL-E-16400, under the condition for meta
42、l combinations subject to spray from sea water, unless otherwise specified herein. If it is necessary to assemble dissimilar metals other than those allowed by MIL-E-16400 in intimate contact with each other, approval shall be obtained from the procuring activity and the metals shall be protected ag
43、ainst electrolytic corrosion in accordance with the methods specified in MIL-E-16400. If electrical considerations preclude the use of such methods, the metal contact shall be protected using the compound specified in 3.5.5. metal connections shall not be required to be made in the field. 3.3.7 Diss
44、imilar metals. Dissimilar metal contacts shall be limited to those specified in Dissimilar MIL-A-Z8768B( EC) Total length of cable (meters (m) (ft) Maximum tolerance mm (in.) 30.48 (over 100) 3.048 to 30.48 (10 to 100) 3.048 (under 10) , 6.35 (0.35) 3.18 (0.125) 1.59 (0.625) These tolerances do not
45、apply to the overall length of a cable containing a turnbuckle or other length adjusting device, nor to structural guy insulator locations. Turnbuckles terminating at the same anchor point shall be separated so that they turn without interference. 3.3.4 Flat washers. Flat washers shall be used to av
46、oid marring the protective finishes of parts being joined by threaded devices. This requirement applies whether connections are made in the factory or in the field. be selected in the descending order of category preference specified in a through ci: a. Category A: Vitrified ceramics in accordance w
47、ith MIL-1-10 in Grades L4 or better b. Category B: Other vitrified ceramics complying with MIL-1-10 c. Category C: Arc-resistant materials listed in MIL-STD-454, Requirement 26 d. Category D: Insulating materials in accordance with MIL-STD-454, Requirement 11 All ceramic insulators shall be glazed.
48、against tracking, erosion, ultraviolet radiation, fungus, and water absorption by utilizing a silicone rubber coating or by other suitable means. (Power O through Power 50) (see 1.2.1). selected from other than Category A and Category B (with coating) shall be subject to successful completion of the
49、 Inclined Plane Test of ASTIII D2303, as modified and specified in 4.5.7. 3.3.3.5 Turnbuckles. 3.3.5 Insulating material. Insulating material for radio frequency (RF) applications shall of stearite, alumina, and forsterite only I Insulators other than ceramic shall be adequately protected Insulator material for use on transmitting antennas, 3.3.5.1 Structural guy cable (see 6.4.1) strain insulators. Structural guy cable strain insulators shall be in accordance with ANSI C29.1 to C29.5 inclusive. Class 54 in the size and strength needed to conform to the requirements of this
