Operator’s, Organizational, Direct Support,General Support, and Depot Maintenance Manual
ANTENNA GROUP AN/GRA-50(NSN 5985-00-892-0758)
TM 11-5820-467-15, 19 July 1961, is changed as follows:
Inside front cover. After the inside front cover, add the following warning and first aidsafety steps.
FIXED OPERATION WITH LONG RANGE ANTENNAS
TELESCOPING
WARNING
TYPICAL TOWER EXTENDED RANGEANTENNA MAST ANTENNA
DOUBLET ANTENNA
NEVER ERECT THESE LONG RANGE ANTENNAS DIRECTLY UNDER POWERLINES.IF YOU MUST ERECT THESE LONG RANGE ANTENNAS NEAR POWERLINES, POWERLINE POLES ORTOWERS, OR BUILDINGS WITH OVERHEAD POWERLINE CONNECTIONS, NEVER PUT THE ANTENNACLOSER THAN TWO TIMES THE ANTENNA HEIGHT FROM THE BASE OF THE POWERLINE, POLE.TOWER OR BUILDINGS.
NEVER ATTEMPT TO ERECT ANY LONG RANGE ANTENNA WITHOUT A FULL TEAM.BEFORE ERECTING ANY LONG RANGE ANTENNA, INSPECT ALL THE PARTS MAKING UP THEANTENNA KIT. DO NOT ERECT THE ANTENNA IF ANY PARTS ARE MISSING OR DAMAGED.
DO AS MUCH OF THE ASSEMBLY WORK AS POSSIBLE ON THE GROUND.
WHEN ERECTING THE ANTENNA, ALLOW ONLY TEAM PERSONNEL IN THE ERECTION AREA.
MAKE SURE THAT THE AREA FOR THE ANCHORS IS FIRM. IF THE GROUND IS MARSHY OR SANDY,GET SPECIFIC INSTRUCTIONS FROM YOUR CREW CHIEF OR SUPERVISOR ON HOW TO REINFORCETHE ANCHORS.
WHEN SELECTING LOCATlONS FOR ANCHORS, AVOID TRAVELED AREAS AND ROADS. IF YOU CANNOTAVOID THESE AREAS, GET SPECIFIC lNSTRUCTlONS FROM YOUR SUPERVISOR AS TO WHAT CLEAR- ANCE YOUR GUY WIRES AND ROPES MUST HAVE OVER THE TRAVELED AREAS AND ROAD.
CLEARLY MARK ALL GUY WIRES AND ROPES WITH THE WARNING FLAGS OR SIGNS SUPPLIED BY YOUR UNIT. IN AN EMERGENCY, USE STRIPS OF WHITE CLOTH AS WARNING STREAMERS.
IF YOU SUSPECT THAT POWERLINES HAVE MADE ACCIDENTAL CONTACT WITH YOUR ANTENNA, STOPOPERATING, ROPE OFF THE ANTENNA AREA, AND NOTIFY YOUR SUPERIORS.
IF THE WEATHER IN YOUR AREA CAN CAUSE ICE TO FORM ON YOUR LONG RANGE ANTENNA AND ITSGUY WIRES AND ROPES, ADD EXTRA GUYS TO SUPPORT THE SYSTEM. ROPE OFF THE AREA ANDPOST IT WITH WARNING SIGNS LIKE "BEWARE OF FALLING ICE."
DO NOT TRY TO ERECT ANY ANTENNA DURING AN ELECTRICAL STORM.
KEEP A SHARP EYE ON YOUR ANCHORS AND GUYS. CHECK THEM DAILY AND IMMEDIATELYBEFORE AND AFTER BAD WEATHER.
SAFETY STEPS TO FOLLOW IF SOMEONEIS THE VICTIM OF ELECTRICAL SHOCK
DO NOT TRY TO PULL OR GRAB THE INDIVIDUAL
IF POSSIBLE, TURN OFF THE ELECTRICAL POWER
IF YOU CANNOT TURN OFF THE ELECTRICALPOWER, PULL, PUSH, OR LIFT THE PERSON TOSAFETY USING A DRY WOODEN POLE OR A DRYROPE OR SOME OTHER INSULATING MATERIAL
SEND FOR HELP AS SOON AS POSSIBLE
AFTER THE INJURED PERSON IS FREE OFCONTACT WITH THE SOURCE OF ELECTRICALSHOCK, MOVE THE PERSON A SHORT DISTANCEAWAY AND IMMEDIATELY START ARTIFICIALRESUSCITATION
Page 5. Paragraph 1.1 is superseded as follows:
1.1. Consolidated Index of Army Publications and Blank Forms
Refer to the latest issue of DA Pam 25-30 to determine whether there are new editions, changes or additionalpublications pertaining to the equipment.
Page 5. Paragraph 2 is superseded as follows:
2. Maintenance Forms, Records and Reports
a. Reports of Maintenance and Unsatisfactory Equipment. Department of the Army formsand procedures used for equipment maintenance will be those prescribed by DA Pam 738-750 as contained inMaintenance Management Update.
b. Report of Item and Packaging Deficiencies. Fill out and forward SF 364 (Report ofDiscrepancy [ROD]) as prescribed in AR 735-11-2/DLAR 4140.55/SECNAVINST 4355.73B/AFR 400-54/MCO4430.3J.
c. Transportation Discrepancy Report (TDR) (SF 361). Fill out and forward TransportationDiscrepancy Report (TDR) (SF 361) as prescribed in AR 55-38/NAVSUPINST 4610.33C/AFR 75-18/MCOP4610.19D/DLAR 4500.15.
Page 5. Paragraph 2.1 is superseded as follows:
2.1 Reporting Errors and Recommending Improvements
You can help improve this manual. If you find any mistakes or if you know of a way to improve the procedures, pleaselet us know. Mail your letter, DA Form 2028 (Recommended Changes to Publications and Blank Forms), or DA Form2028-2 located in back of this manual direct to: Commander, US Army Communications-Electronics Command andFort Monmouth, ATTN: AMSEL-LC-ME-PS, Fort Monmouth, New Jersey 07703-5000.
In either case, a reply will be furnished direct to you.
Page 5. Paragraph 2.3 is superseded as follows:
2.3 Destruction of Army Electronics Material
Destruction of Army electronics material to prevent enemy use shall be in accordance with TM 750-244-2.
If your AN/GRA-50 needs improvement, let us know. Send us an EIR. You, the user, are the only one who can tellus what you don’t like about your equipment. Let us know why you don’t like the design or performance. Put it onan SF 368 (Product Quality Deficiency Report). Mail it to: Commander, US Amy Communications-Electronics Commandand Fort Monmouth, ATTN: AMSEL-PA-MA-D, Fort Monmouth, New Jersey 07703-5000. We’ll send you a reply.
Page 9. The following note is added after paragraph llb(3):
NOTE
To determine the correct lengthof antenna wire that is requiredto obtain the desired correspondingfrequency, use the followingformula:
This formula should be imprintedon the case of the tape measureas a ready reference and con-venience to installation personnel.
Page 14. Paragraph 13.2 is superseded as follows:
13.2. Operator’s Daily Preventive Maintenance Checks and Services
B - BEFORE A - AFTER W - WEEKLY
ITEMNO.
1
2
3
INTERVAL
wITEM
AntennaAssembly
AntennaAssembly
RF Cable
AntennaAssembly
ITEM TO BE INSPECTEDPROCEDURE
Inspect the antenna assemblyfor completeness (App. II)
Inspect the antenna assemblyfor cleanliness (para. 13.3)
Inspect the rf cable for cuts,breaks, and undue strain (fig. 1).
Check the antenna assembly for normaloperation when connected to a transmitteror receiver.
EQUIPMENT IS NOTREADY/AVAILABLE IF:
RF cable lackscontinuity.
Weak or notransmissionor reception.
4
Page 22. Appendix I is superseded as follows:
APPENDIX IREFERENCES
Following is a list of applicable references that are available to the operator and unit repairman ofAntenna Group AN/GRA-50.
DA Pam 25-30 Consolidated Index of Army Publications and Blank Forms.DA Pam 738-750 The Army Maintenance Management System (TAMMS).TM 11-5820-295-10 Operator’s Manual for Radio Set AN/GRC-19 (NSN
5820-00-030-0155).TM 11-5820-295-20 Organizational Maintenance for Radio Set AN/GRC-19
5820-00-030-0155).TM 11-5820-467-24P Organizational, Direct Support and General Support Maintenance
Repair Parts and Special Tools Lists (Including Depot MaintenanceRepair Parts and Special Tools) for Antenna Group AN/GRA-50(NSN 5985-00-892-0758).
TM 43-0139 Painting Instructions for Field Use.TM 750-244-2 Procedures for Destruction of Electronics Material to Prevent Enemy
Use (Electronics Command).
By Order of the Secretary of the Army:
Official:
WILLIAM J. MEEHAN IIBrigadier General, United States Army
The Adjutant General
CARL E. VUONOGeneral, United States Army
Chief of Staff
DISTRIBUTION:To be distributed in accordance with DA Form 12-51 Operator, Unit,
and DS/GS requirements for AN/GRA-50.
PIN: 018745-007
Changes in force: C 3, C 5, and C 6
CHANGE
No. 6
TM 11-5620-467-15C 6
HEADQUARTERSDEPARTMENT OF THE ARMY
WASHINGTON , DC, 9 September 1977
Operator’s, Organizational, Direct Support,General Support, and Depot Maintenance Manual
ANTENNA GROUP AN/GRA-50(NSN 5985-00-892-0758)
TM 11-5820-467-15, 19 July 1961, is changed as follows:The title is changed as shown above.
Page 5. Paragraph 2 is superseded as follows:
2. Forms and Recordsa. Reports of Maintenance and Unsatisfactory
Equipment. Maintenance forms, records, andreports which are to be used by maintenancepersonnel at all maintenance levels are listed inand prescribed by TM 38-750.
b. Report of Packaging and Handling De-ficiencies. Fill out and forward DD Form 6(Packaging Improvement Report) as prescribedin AR 700-58/NAVSUPINST 4030.29/AFR 71-13/MCO P4030.29A, and DSAR 4145.8.
c. Discrepancy in Shipment Report (DISREP)(SF 361). Fill out and forward Discrepancy inShipment Report (DISREP) (SF 361) as pre-scribed in AR 55-38/NAVSUPINST 4610.33A/AFR 75-18/MCO P4610.19B and DSAR 4500.15.
Paragraph 2.4 is added after paragraph 2.3.
2-4. Reporting EquipmentRecommendations (EIR)EIR’s will be prepared using
Improvement
DA Form 2407(Maintenance Request). Instructions for pre-paring EIR’s are provided in TM 38-750, TheArmy Maintenance Management System.EIR’s should be mailed direct to Commander,US Army Electronics Command, ATTN:DRSEL-MA-Q, Fort Monmouth, NJ 07703. Areply will be furnished direct to you.
Paragraph 3b, line 7, change "100 watts" toread "500W."
Paragraph 4, line 4, change "100 watts" toread "500 W."
Page 25. Appendix III is superseded asfollows:
APPENDIX IllMAINTENANCE ALLOCATION
Section 1. INTRODUCTION
1. General specific maintenance functions on repairableitems and components and the tools and equip-
This appendix provides a summary of the ment required to perform each function. Thismaintenance operations for AN/GRA-50. It appendix may be used as an aid in planningauthorizes categories of maintenance for maintenance operations.
1
2. Maintenance FunctionMaintenance functions will be limited to anddefined as follows:
a. Inspect. To determine the serviceability ofan item by comparing its physical, mechanical,and/or electrical characteristics with estab-lished standards through examination.
b. Test. To verify serviceability and to detectincipient failure by measuring the mechanicalor electrical characteristics of an item andcomparing those characteristics with prescribedstandards.
c. Service. Operations required periodically tokeep an item in proper operating condition, i.e.,to clean (decontaminate), to preserve, to drain,to paint, or to replenish fuel, lubricants, hy-draulic fluids, or compressed air supplies.
d. Adjust. To maintain, within prescribedlimits, by bringing into proper or exact position,or by setting the operating characteristics to thespecified parameters.
e. Align. To adjust specified variable elementsof an item to bring about optimum or desiredperformance.
f. Calibrate. To determine and cause correc-tions to be made or to be adjusted on instru-ments or test measuring and diagnostic equip-ments used in precision measurement. Consistsof comparisons of two instruments, one of whichis a certified standard of known accuracy, todetect and adjust any discrepancy in theaccuracy of the instrument being compared.
g. Install. The act of emplacing, seating, orfixing into position an item, part, module(component or assembly) in a manner to allowthe proper functioning of the equipment orsystem.
h. Replace. The act of substituting a service-able like type part, subassembly, or module(component or assembly) for an unserviceablecounterpart.
i. Repair. The application of maintenanceservices (inspect, test, service, adjust, align,calibrate, replace) or other maintenance actions(welding, grinding, riveting, straightening, fac-ing, remachining, or resurfacing) to restoreserviceability to an item by correcting specificdamage, fault, malfunction, or failure in a part,subassembly, module (component or assembly),end item, or system. This function does notinclude the trial and error replacement ofrunning spare type items such as fuses, lamps,or electron tubes.
2
j . Overhaul. That maintenance effort(service/action) necessary to restore an item to acompletely serviceable/operational condition asprescribed by maintenance standards (i.e.,DMWR) in. appropriate technical publications.Overhaul is normally the highest degree ofmaintenance performed by the Army. Overhauldoes not normally return an item to like newcondition.
k. Rebuild. Consists of those services/actionsnecessary for the restoration of unserviceableequipment to a like new condition in accordancewith original manufacturing standards. Re-build is the highest degree of materiel mainte-nance applied to Army equipment. The rebuildoperation includes the act of returning to zerothere age measurements (hours, miles, etc.)considered in classifying Army equipments/components.
3. Column Entriesa. Column 1, Group Number. Column 1 lists
group numbers, the purpose of which is toidentify components, assemblies, subas-semblies, and modules with the next higherassembly.
b. Column 2, Component/Assembly. Column 2contains the noun names of components, as-semblies, subassemblies, and modules for whichmaintenance is authorized.
c. Column 3, Maintenance Functions. Column3 lists the functions to be performed on the itemlisted in column 2. When items are listed withoutmaintenance functions, it is solely for purpose ofhaving the group numbers in the MAC andRPSTL coincide.
d. Column 4, Maintenance Category. Column 4Specifies, by the listing of a "work time" figure in
the appropriate subcolumn(s), the lowest level ofmaintenance authorized to perform the func-tion listed in column 3. This figure representsthe active time required to perform thatmaintenance function at the indicated categoryof maintenance. If the number or complexity ofthe tasks within the listed maintenance func-tion vary at different maintenance categories,appropriate "work time" figures will be shownfor each category. The number of task-hoursspecified by the "work time" figure representsthe average time required to restore an item(assembly, subassembly, component, module,end item or system) to a serviceable conditionunder typical field operating conditions. Thistime includes preparation time, troubleshooting
time, and quality assurance/quality control timein addition to the time required to perform thespecific tasks identified for the maintenancefunctions authorized in the maintenance alloca-tion chart. Subcolumns of column 4 are asfollows:
C - Operator/CrewO - OrganizationalF - Direct SupportH - General SupportD - Depot
e. Column 5, Tools and Equipment. Column 5specifies by code, those common tool sets (notindividual tools) and special tools, test, andsupport. equipment required to perform thedesignated function.
f. Column 6, Remarks. Column 6 contains analphabetic code which leads to the remark insection IV, Remarks, which is pertinent to theitem opposite the particular code.
4. Tool and Test Equipment Require-ments (Sect. III)
a. Tool or Test Equipment Reference Code. Thenumbers in this column coincide with the
numbers used in the tools and equipmentcolumn of the MAC. The numbers indicate theapplicable tool or test equipment for themaintenance functions.
b. Maintenance Category. The codes in thiscolumn indicate the maintenance categoryallocated the tool or test equipment.
c. Nomenclature. This column lists the nounname and nomenclature of the tools and testequipment required to perform the mainte-nance functions.
d. National/NATO Stock Number. This columnlists the National/NATO stock number of thespecific tool or test equipment.
e. Tool Number. This column lists the man-ufacturer’s part number of the tool followed bythe Federal Supply Code for manufacturers(5-digit) in parentheses.
5. Remarks (Sect. IV)a. Reference Code. This code refers to the
appropriate item in section II, column 6.b. Remarks. This column provides the re-
quired explanatory information necessary toclarify items appearing in section II.
3
(1)GROUP
NUMBER
00
SECTION I I MAINTENANCE ALLOCATION CHARTFOR
ANTENNA GROUP AN/GRA-50
(2)COMPONENT/ASSEMBLY
ANTENNA GROUP AN/GRA-50
(3)MAINTENANCE
FUNCTION
InspectServiceTestReplaceRepair
4
(4)MAINTENANCE CATEGORY
c
0.10.2
O
0.20.2
F
0.2
H D
(5)TOOLSANDEQPT.
1,21,23,4
(6)REMARKS
AABCD
SECTION III. TOOL AND TEST EQUIPMENT REQUIREMENTSFOR
ANTENNA GROUP AN/GRA-50
TOOL OR TEST MAINTENANCEEQUIPMENT CATEGORY
NOMENCLATURE NATIONAL/NATO
REF CODESTOCK NUMBER TOOL NUMBER
1 O MULTIMETER AN/URM-105 6625-00-581-2036
2 O TOOL KIT, ELECTRONIC EQUIPMENT TK-101/G 5180-00-064-5178
3 F TOOL KIT, ELECTRONIC EQUIPMENT TK-105/G 5180-00-610-8177
4 F MULTIMETER TS-352/U 6625-00-242-5023
5
SECTION IV. REMARKS
ANTENNA GROUP AN/GRA-50
REFERENCECODE
REMARKS
A Preventive maintenance.
B Continuity and leakage tests of cable CG-678/U.
C Replace components.
D Repair of RF cable assembly.
6
By Order of the Secretary of the Army:
Official:
BERNARD W. ROGERSGeneral, United States Army
Chief of Staff
J.C. PENNINGTONBrigadier General, United States Army
The Adjutant General
Distribution:To be distributed in accordance with DA Form 12-51, Operator TM literature requirements for
AN/GRA-50.
7
2 3 4 - 3 7 7 0 - 8 9 - 2
Changes In force: C 3, and C5
Change
No. 5
TM 11-5820-467-15* C 5
HEADQUARTERS,DEPARTMENT OF THE ARMY
Washington, D. C., 28 December 1973
Operator’s Organizational, Direct Support,General Support, and Depot Maintenance Manual
ANTENNA GROUP AN/GRA-50
TM 11-5820-467-15, 19 July 1961, is changed as follows:The title of the manual is changed as shownabove.Page 5. Paragraph 1.1 is superseded by thefollowing:
1.1. Indexes of Publicationsa. DA Pam 310-4. Refer to the latest issue of
DA Pam 310-4 to determine whether there arenew editions, changes, or additional publica-tions pertaining to the equipment.
b. DA Pam 310-7. Refer to DA Pam 310-7 todetermine whether there are modificationwork orders (MWO’s) pertaining to the equip-ment.
Paragraph 2 is superseded by the follow-ing:2. Forms and Records
a. Reports of Maintenance and Unsatisfac-tory Equipment. Maintenance forms, records,and reports which are to be used by mainte-nance personnel at all maintenance levels arelisted in and prescribed by TM 38-750.
b. Report of Packaging and Handling De-ficiencies. Fill out and forward DD Form 6(Report of Packaging and Handling Deficien-c ies) as prescribed in AR 700-58(Army)/NAVSUP PUB 378 (Navy )/AFR 71-4(Air Force)/and MCO P4030.29 (Marine Corps).
c. Discrepancy in Shipment Report (DIS-REP) (SF 361). Fill out and forward Discre-pancy in Shipment Report (DISREP) (SF 361)as prescribed in AR 55-38 (Army)/NAVSUP
Paragraph 2.1 is added as follows:2.1. Reporting of ErrorsThe reporting of errors, omissions, and re-commendations for improving this publicationby the individual user is encouraged. Reportsshould be submitted on DA Form 2028, Re-commended Changes to Publications, and for-warded direct to Commander, US Army Elec-tronics Command, ATTN: AMSEL-MA-CR,Fort Monmouth, NJ 07703.
2.2. Administrative StorageFor procedures, forms and records, and in-spection required for equipment in adminis-trative storage, refer to TM 740-90-1.
2.3. Destruction of Army Materiel to Pre-vent Enemy UseFor information on this subject, refer to TM750-244-2.
5985-757-2130 2 Wire Assembly, AntennaCX-7303/G (160 ft0 in.).Note: Stored and
used with (but notp/o) Reel RC-432/G(Not installed)
Page 8. Paragraph 9b is superseded by the fol-lowing:
b. See that the equipment is complete aslisted on the packing slip. If a packing slip isnot available, check the equipment againstparagraph 5 and appendix II.Page 9, paragraph 11a (2). Add the followingdata to the chart:
Frequency(mc)
21
22
23
2425
26
2728
29
30
Length of eachantenna wire a
(ft)11.27
10.63
10.25
9.729.35
9.008.758.35
8.00
7.80
Page 14, paragraph 13.3. Delete the warningnotice and substitute the following:
WARNINGThe fumes of cleaning compound,Trichloroethane (FSN 6810-292-9625, 1 qt) are toxic. Provide enoughventilation whenever used. Do notuse near an open flame. Trich-loroethane is not flammable, but ex-posure to an open flame converts thefumes to a highly toxic and danger-ous gas.
Page 17, paragraph 16b(1). Paragraph 16b(1) issuperseded by the following:
(1) Cleaning compound, Trichloroethane(FSN 6810-292-9625; (1 qt)). Observe the warn-ing in paragraph 13.3.
Page 22, appendix I. Make the followingchanges:Change the title of DA Pam 310-4 to read:Index of Technical Manuals, Technical Bulle-tins, Supply Manuals (types 7, 8, and 9), SupplyBulletins, and Lubrication Orders.Change the title of TM 38-750 to read: TheArmy Maintenance Management System(TAMMS).
Add the following:
TM 740-90-1 Administrative Storage ofEquipment,
TM 750-244-2 Procedures for Des-truction of ElectronicsMateriel to PreventEnemy Use (Elec-tronics Command).
DA Pam 310-7 U.S. Army Equip-ment Index ofModification WorkOrders.
Page 23. Appendix II is superseded by the fol-lowing:
2
APPENDIX IIBASIC LIST ITEMS LIST (BIIL) AND ITEMS TROOP
INSTALLED OR AUTHORIZED LIST (ITIAL)
Section I. INTRODUCTION
1. Scope.This appendix lists basic issue items and itemstroop installed or authorized required by thecrew/operator for installation, operations, andmaintenance of Antenna Group AN/GRA-50.
2. GeneralThis Basic Issue Items and Items Troop In-stalled or Authorized List is divided into thefollowing sections:
a. Basic Issue Items List - Section II. A list,in alphabetical sequence, of items which arefurnished with, and which must be turned inwith the end item.
b. Items Troop Installed or Authorized List -Section III. A List, in alphabetical sequence ofitems which, at the discretion of the unit com-mander, may accompany the end item, but arenot subject to be turned in with the end item.
3. Explanation of Columns.The following provides an explanation of col-umns found in the tabular listings:
a. Illustration. This column is divided as fol-lows:
(1) Figure number. Indicates the figurenumber of the illustration in which the item isshown.
(2) Item number. Not applicable.b. Federal Stock Number. Indicates the Fed-
eral stock number assigned to the item andwill be used for requisitioning purposes.
c. Part Number. Indicates the primarynumber used by the manufacturer (individual,company, firm, corporation, or Governmentactivity), which controls the design andcharacteristics of the item by means of its en-gineering drawings, specifications standards,and inspection requirements, to identify anitem or range of items.
d. Federal Supply Code for Manufacturer(FSCM). The FSCM is a 5-digit numeric codeto identify the manufacturer, distributor, orGovernment agency, etc., and is identified inSB 708-42.
e. Description. Indicates the Federal itemname and a minimum description required toidentify the item.
f. Unit of Measure (U/M). Indicates the stan-dard of basic quantity of the listed item as usedin performing the actual maintenance func-tion. This measure is expressed by a two-character alphabetical abbreviation, (e.g., ea,in, pr, etc). When the unit of measure differsfrom the unit of issue, the lowest unit of issuethat will satisfy the required units of measurewill be requisitioned.
g. Quantity Furnished with Equipment(Basic Issue Items Only). Indicates the-quan-tity of the basic issue item furnished with theequipment.
h. Quantity Authorized (Items Troop Instal-led or Authorized Only). Indicates the quan-tity of the item authorized to be used with theequipment.
Section Il. BASIC ISSUE ITEMS LIST
3
Section III. ITEMS TROOP INSTALLED OR AUTHORIZED LIST
By Order of the Secretary of the Army:
CREIGHTON W. ABRAMS
Official:VERNE L. BOWERSMajor General, United States ArmyThe Adjutant General
General, United States ArmyChief of Staff
Distribution:To be distributed in accordance with DA Form 12-51 (qty rqr block No. 45), Operator requirements for AN/GRA-50.
4
Change in force: C 3
Operator, Organizational, Field and Depot
TM 11-5820-467-15*C 3
Maintenance Manual
ANTENNA GROUP AN/GRA-50
HEADQUARTERSDEPARTMENT OF THE ARMYWASHINGTON , D.C., 28 April 1984
TM 11-5820-467-15, 19 July 1961, is changed as follows:
Page 5 (as changed by C 2, 4 Sep 63). Make thefollowing changes:
Add paragraph 1.1 after paragraph 1.
1.1. Index of Publications
Refer to the latest issue of DA Pam 310-4 todetermine whether there are new editions, changes,or additional publications pertaining to the equip-ment. DA Pam 310-4 is an index of current tech-nical manuals, technical bulletins, supply manuals,supply bulletins, lubrication orders, and modifica-tion work orders available through publicationssupply channels. The index lists the individualparts (-10, -20, -35P, etc. ) and the latest changesto and revisions of each equipment publication.
Delete paragraph 2 and substitute:
2. Forms and Records
a. Reports of Maintenance and UnsatisfactoryEquipment. Use equipment forms and records inaccordance with instructions in TM 38-750.
b. Report of Damaged or Improper Shipment.Fill out and forward DD Form 6 (Report of Dam-aged or Improper Shipment) as prescribed in AR700-58 (Army) NAVASANDA Publication 378(Navy), and AFR 71-4 (Air Force).
c. Reporting of Equipment Manual Improve-ments. The direct reporting, by the individualuser, of errors, omissions, and recommendationsfor improving this manual, is authorized and en-couraged. DA Form 2028 (RecommendedChanges to DA Technisal Manual Parts Lists orSupply Manual 7, 8, or 9) will be used for reportingthese improvements. This form will be completedin triplicate using pencil, pen, or typewriter. Theoriginal and one copy will be forwarded direct toCommanding Officer, U. S. Army Electronics
* This change supercedes C 2, 4 September I963.
Materiel Support Agency, ATTN: SELMS-MP,Fort Monmouth, N. J. 07703. One informa-tion copy will be furnished to the individual’simmediate supervisor (officer, noncommissionedofficer supervisor, etc.).
Page 8. Delete paragraph 9 and substitute:
9. Checking Unpacked Equipment
a. Inspect the equipment for damage incurredduring shipment. If the equipment has beendamaged, report the damage on DD Form 6(para. 2).
b. See that the equipment is complete as listedon the packing slip. If a packing slip is not avail-able, check the equipment against the basic issueitems list (app. II). Report all discrepancies inaccordance with TM 38-750. Shortage of a minorassembly or part that does not affect properfunctioning of the equipment should not preventuse of the equipment.
Page 9, paragraph llb(9). Make the followingchanges:
Add the following after the last sentence:Place the antenna as high as possible.
Caution. line 2. Change "6" to: 24.Page 14 (as changed by C 2, 4 Sep 63). Delete
paragraph 13 and substitute:
13. Operator’s Preventive Maintenance
Preventive maintenance is the systematic care,servicing, and inspection of equipment to preventthe occurrence of trouble, to reduce downtime, andto assure that the equipment is serviceable.
a. Systematic Care. The procedures given inparagraphs 13.1 and 13.2 cover routine systematiccare and cleaning essential to proper up keep andoperation of the equipment.
1
234-377 0 - 89 - 1
13.2.
App. II.
Para. 13.3.
Fig. 1.
Fig. 1.
b. Preventive Maintenance Checks and Services.The preventive maintenance checks and serviceschart (para. 13.2) outlines functions to be per-formed at specific intervals. These checks andservices are to maintain Army electronic equip-ment in a combat serviceable condition; that is, ingood general (physical) condition and in goodoperating condition. To assist operators in main-taining combat serviceability, the chart indicateswhat to check, how to check, and what the normalconditions are. The References column lists theillustrations, paragraphs, or manuals that containdetailed repair or replacement procedures. If thedefect cannot be remedied by the operator, higherechelon maintenance or repair is required. Re-cords and reports of these checks and servicesmust be made in accordance with the requirements
set forth in TM 38-750.Add paragraphs 13.1, 13.2, and 13.3 after
paragraph 13.
13.1. Operator’s Preventive MaintenanceChecks and Services Periods
Preventive maintenance checks and services onthe AN/GRA-50 are required on a daily basis.Paragraph 13.2 specifies services and inspectionsthat must be accomplished daily and under specialconditions listed below.
a. When the antenna is initially installed.b. When the antenna is reinstalled after being
taken down for any reason.c. At least once each week if the antenna is
maintained in standby condition.
13.3. Cleaning
Inspect all components. They must be free ofdirt, grease, and fungus.
Warning: Cleaning Compound (Federal stockNo. 7930-395-9542( is flammable and its fumes aretoxic. Do not use near a flame; provide adequateventilation.
a. Remove grease and fungus from the antennaassembly. Use a cloth dampened (not wet) withcleaning compound.
b. Remove dirt from components with a brush.Add paragraph 14.1 after paragraph 14.
14.1. Replacing Broken Wire Ends
If the looped end of one of the wires (shownunder the outer wingnuts in fig. 5) breaks off,replace it as follows:
a. Loosen the wingnut and remove the brokenloop.
b. Unwind all the wire from the reel assembly.c. Remove the outer wingnut from the reel
assembly (fig. 6) and slip off the looped end.d. Slip the loop under the wingnut (a above)
and tighten the nut.
2
e. Starting with the broken end, rewind thewire onto the reel assembly.
Page 15 (as changed by C 2, 4 Sep 63). Deletefigure 8.
Page 16 (as changed by C 2, 4 Sep 63). Deletefigure 9.
Page 17 (as changed by C 2, 4 Sep 63). Deleteparagraph 17 and substitute:
17. Organizationl Preventive Maintenance
a. Preventive maintenance is the systematiccare, inspection, and servicing of equipment tomaintain it in serviceable condition, preventbreakdowns, and assure maximum operationalcapability. Preventive maintenance is the responsi-bility of all echelons concerned with the antennaassembly and includes the inspection, testing, andrepair or replacement of components that inspec-tion and tests indicate probably would fail beforethe next scheduled periodic service. Preventivemaintenance checks and services on the antennaassembly at the second echelon level are made atmonthly intervals unless otherwise directed by thecommanding officer.
Fig. 6.
Fig. 5.
Fig. 2.
Fig. 2.
b. Maintenance forms and records to be used in paragraph 17.2 once each month. When theand maintained on the antenna assembly are antenna assembly is maintained in a standbyspecified in TM 38-750. (ready for immediate operation) condition, per-
Add paragraphs 17.1 and 17.2 after paragraph form the monthly preventive maintenance checks.17. Equipment in limited storage (requires service17.1. Monthly Maintenance before operation) does not require monthly pre-
Perform the maintenance functions indicated ventive maintenance.
17.2. Monthly Preventive Maintenance Checks and Services Chart
Page 22 (as changed by C 2, 4 Sep 63). Add the Work Orders.following to appendix I: TM 9-213 Painting Instructions for FieldDA Pam 310-4 Index of Technical Manuals, use.
Technical Bulletins, Supply TM 38-750 Army Equipment Record Pro-Manuals (types 4, 6, 7, 8, and cedures.9), Supply Bulletins, Lubrica- Page 23 (as changed by C 2, 4 Sep 63). Deletetion Orders, and Modification appendix II and substitute:
APPENDIX II
BASIC ISSUE ITEM LIST
Section I. INTRODUCTION
1. GeneralThis appendix lists items supplied for initial
operation. The list includes tools, parts, andmateriel issued as part of the major end item.The list includes all items authorized for basicoperator maintenance of the equipment. Enditems of equipment are issued on the basis ofallowance prescribed in equipment authorizationtables and other docurments that are a basis forrequisitioning.
2. Columns
Columns are as follows:a. Federal Stock Number. This column lists the
11-digit Federal stock number.b. Designation by Model. Not used.
c. Description. Nomenclature or the standarditem name and brief identifying data for each itemare listed in this column. When requisitioning,enter the nomenclature and description.
3
Section II.
d. Unit of Issue. The unit of issue is each, f. Quantity Authorized. Under "Items Comprisunless otherwise indicated, and is the supply term ing an Operable Equipment", the column lists theby which the individual item is counted for pro- quantity of items supplied for the initial operationcurement, storage, requisitioning, allowances, and of the equipment.issue purposes. g. Illustrations. The numbers in the "Figure
e. Expendability. Nonexpendable items are No." column refer to the illustrations where theindicated by NX. Expendable items are not noted. parts are shown.
4
By Order of the Secretary of the Army:
EARLE G. WHEELER,General, United States Army,Chief of Staff.Official:
J. C. LAMBERT,Major General, United States Army,The Adjutant General.
Distribution:Active Army:
USASA (2) Lexington (12), Ft Worth (8)CNGB (1) Tobyhanna (12), Sharpe (3)C/COMMEL (7) Letterkenny (5)cofT (1) Sig Sec, GENDEP (OS) (5)CofEngrs (1) USASCC (4)TSG (1) USA Elct Mat Agcy (9)CofsptS (1) USASA 1st Fld Sta (5)USCONARC (5) USATC AD (3)USAMC (5) USATC Armor (3)USAARMBD (2) USATC Engr (3)USAARTYBD (2) USATC Inf (3)USAECDA (2) USASTC (3)USACBRCDA (1) WRAMC (1)USAMSCDA (2) Army Pic Cen (2)USAOCDA (2) USA Equip Spt Cen (1)USAQMCDA (2) USAERDL (2)USATCDA (2) USA Cold Rgn RE Lab (2)USACECDA (1) Chicago Proc Dist (1)USACECDA (Monmouth Ofc) (1) AMS (1)USAADCDA (2) USATCARC (1)USAARMCDA (2) USATCA (1)USAAVNCDA (2) USATCG (1)USAARTYCDA (2) USATCP (1)USASWCDA (1) USAERDLA (White Sands) (13)UAECOM (7) USAELRDL Trp Comd (10)USAMICOM (4) Army Tml (1) except Oakland (5)USASMCOM (2) POE (1)ARADCOM (2) Sig Fld Maint Shops (3)ARADCOM Rgn (2) WSMR (5)OS Maj Comd (3) Units org under fol TOE: (2 copiesOS Base Comd (2) each except as indicated)LOGCOMD (2) 1-55 5-155 10-105MDW (1) 1-75 5-156 10-106Armies (2) 1-76 5-157 10-107Corps (2) l-ro c mn 1 n-701
USA Corps (3) 1-127 6-501 10-20211th Air Assault Div (3) 1-137 7 10-206Instl (2) except Ft Gordon (5) 1-207 7-25 10-445
Ft Hancock (4), Ft Huachuca (10) 5-25 7-26 10-446Ft Monmouth (63) 5-26 7-100 10-500
Savanna (5), Sacramento (28) 5-148 10-22 11-97NG: State AG (3); units—same as Active Army except allowance is one copy to each unit.USAR: N o n e .For explanation of abbreviations used, see AR 320-50.
Figure 1. Antenna Group AN/GRA-50, typical installation.
4
CHAPTER 1INTRODUCTION
Section I. GENERAL
1. Scope
This manual describes Antenna GroupAN/GRA-50 (fig. 1) and covers installa-tion, maintenance, and theory of operation.
2. Forms and Records
a. Unsatisfactory Equipment Report.(1)
(2)
Fill out and forward DA Form 468(Unsatisfactory Equipment Report)to Commanding Officer, U. S. ArmySignal Materiel Support Agency,ATTN: SIGMS-ML, Fort Mon-mouth, N. J., as prescribed in AR700-38.Fill out and forward AF TO Form29 (Unsatisfactory Report) to theCommander, Air Materiel Com-mand, Wright-Patterson Air ForceBase, Ohio, as prescribed in AFTO 00-35D-54.
b. Report of Damaged or Improper Ship-ment. Fill out and forward DD Form 6
(Report of Damaged or Improper shipmentas prescribed in AR 700-58 (Army), NavyShipping Guide, Article 1850-4 (Navy), andAFR 71-4 (Air Force).
c. Preventive Maintenance Form. Pre-pare DA Form 11-238 (fig. 8 and 9) (Maint-enance Check List for Signal Equipment(Sound Equipment, Radio, Direction Find-ing, Radar, Carrier, Radiosonde and Tele-vision) ), in accordance with the instruc-tions on the form.
d. Parts List Form. Forward DA Form2028 (Recommended Changes to DA Tech-nical Manual Parts Lists or Supply Manual7, 8, or 9) direct to the Commanding Offi-cer, U. S. Army Signal Materiel SupportAgency, ATTN: SIGMS-ML, Fort Mon-mouth, N. J., with comments on appendixesII and III.
e. Comments on Manual. Forward allother comments on this publication directto the Commanding Officer, U. S. ArmySignal Materiel Support Agency, ATTN:SIGMS-PA2d, Fort Monmouth, N. J.
Section Il. DESCRIPTION AND DATA
3. Purpose and Use
a. Purpose. Antenna Group AN/GRA-50(fig. 1) is a doublet antenna assembly usedfor the transmission and reception of radiosignals between 1.5 and 20 megacycles(mc).
b. Use. Antenna Group AN/GRA-50 isused primarily with Radio Set AN/GRC-19for greater range and reliability than thestandard 15-foot whip antenna provides. Itcan be used with any radio set that has the
proper frequency range and a transmitterpower output of less than 100 watts at anoutput impedance of approximately 50ohms.
4. Technical Characteristics
Antenna type . . . . . . . Half way doublet.Frequency range . . . . . 1.5 to 20 mc.Power handling
a. Bag BG-175, made of heavy canvas,is used to store all components.
b. Each Reeling Machine, Cable, HandRC-432/G consists of a reel on which 160feet of Wire Assembly, Antenna CX-7303/G is wound. A terminal hook on theloose end of Wire Assembly, Antenna CX-7303/G attaches to Insulator IL-4/GRA-4.Halyard MX-2706/G is secured to a smallhole in the Reeling Machine, Cable, HandRC-432/G frame. A spring action handleon the outer flange of the spool facilitateswinding.
c. Cable Assembly, RF CG-678/U is 75feet 3 inches long and consists of cableRG-58A/U with a connector UG-536/U ateach end. Cable Assembly RD CG-78/Uconnects between Insulator IL-4/GRA-4and the radio set.
d. Insulator IL-4/GRA is a phenolichousing which has two terminals for con-nection of the antenna wires and a femalecoaxial fitting for connecting Cable As-sembly RF CG-678/U. Insulator IL-4/GRA-4 is installed at the center of theantenna assembly.
e. Halyard MX-2706/G consists of 75feet of l/8-inch diameter Dacron rope.A snaphook fastener at one end of the ropeconnects to Reeling Machine, Cable, HandRC-432/G, a snaphook fastener and a leadweight is attached to the other end.
f. The tape, measuring (tape measure),made of nonconducting woven fabric, is156 feet long. It is calibrated on one sidein feet and on the other side in frequency.It is used to measure the length of antennanecessary for operation at any given fre-quency. The tape measure is marked ateach 100 kilocycles (kc) from 1.6 to 6 mc,at each 200 kc from 4 to 6 mc, at each500 kc from 6 to 10 mc, and at each mcfrom 10 to 20 mc.
7
CHAPTER 2INSTALLATION
8. Unpacking
a. Packaging Data. When packed forshipment, the components of the antennaassembly are individually enclosed inpolyethylene envelopes and packed in BagBG-175. Bag BG-175 is enclosed in amoistureproof barrier and sealed in a cor-rugated fiberboard carton. Packed forshipment, the carton weighs 13 pounds andis 10 inches high, 9 inches deep, and 10inches wide; its volume is 0.5 cubic feet.A typical shipping carton and its contentsare shown in figure 3.
b. Removing contents. To unpack theequipment, proceed as follows:
(1)
(2)
(3)
(4)
Open the carton. Do not cut openthe carton, because the equipmentmay become damaged.Open the moistureproof barrierand remove Bag BG-175.Open Bag BG-175 and remove itscontents.Remove the components from thepolyethylene evelopes.
9. Checking Unpacked Equipment
a. Inspect the equipment for damage in-curred during shipment. If the equipmenthas been damaged, refer to paragraph 2.
b. See that the equipment is complete aslisted on the packing slip. If a packing slipis not available, check the equipmentagainst the table of components (para 5) orbasic issue items list (appx II).
10. Siting
a. In areas, such as jungles, wherevegetation is very dense, vertical antennas
are inefficient because of the absorption oftheir radiation by the surrounding growth.The antenna assembly, however, providesmore reliable communications than avertical antenna in dense growth areas.
b. Locate the antenna in a clearing andassemble the antenna with the antenna wirebroadside to the direction of the desiredstation. When communication is desiredwith two or more stations, orient the an-tenna assembly so that the antenna wire isbroadside to the weakest station.
11. Installation
a. Determining Length of Antenna Wire.(1)
(2)
In the installation procedure in bbelow, use the tape measure to de-termine the proper length of an-tenna wire for the desired fre-quency of operation. Unroll the tapemeasure to the desired frequencymarking and unroll an equal amountof antenna wire from each reel as-sembly (fig. 4). The length indi-cated on the tape measure oppositethe desired frequency marking ishalf of the required total antennalength at that frequency.The following chart lists the lengthof each antenna wire (including thereel assembly frame) required forfrequencies between 1.5 and 20 mc.When the tape measure is not avail-able, use the chart to determineeach antenna wire length. Pace off(one stride is approximately 3feet)the indicated antenna length; makefinal adjustment by lengthening orshortening the antenna assemblyfor the best transmitter loading.
Connect the antenna wire terminalhooks to the thumb nuts on the op- (6)posite ends of the insulator (fig. 5).Temporarily fasten the insulator toone of the desired supports.Temporarily fasten the free end of (7)the tape measure to the center ofthe insulator.Unwind the tape measure to thelength corresponding to the desiredfrequency.Refer to figure 6 and unroll a like
(d) Tighten the thumb nut at the cen-ter of the reel.
Unfasten the tape measure from theinsulator, unfasten the insulatorfrom the support, and lay the an-tenna wires out in a straight line.Check the overall length of the twowires plus the insulator and reelassemblies. The overall length willbe twice the length indicated on thetape measure for the desired fre-quency or twice the length obtainedfrom the chart in a (2) above. Adjust
amount of wire from each reel as-sembly as follows:
the antenna for an exact overalllength. Be sure to keep the insula-
(a)
(b)
(c)
Grasp the reel assembly firmlyin one hand and loosen the thumb (8)nut at the center of the reel andthe thumb nut on the wire clamp (9)on the reel assembly frame.Move away from the antenna cen-ter slowly, keeping the wire tautat all times. Hold your thumb onthe wire to prevent backlash.After unwinding the required (10)amount of wire, tighten the thumbnut on the wire clamp.
tor centered.Attach each reel assembly to ahalyard snaphook fastener (fig. 7).Tie the halyards to the best avail-able supports (tree, fence post,vehicle, etc) at a height of 4 feet orhigher.
Caution: Allow the antenna as- sembly to sag at least 6 inches.Connect the ends of the rf cablebetween the insulator connector(fig. 5) and the antenna connector
9
on the radio set. Shorten orlengthen the antenna assembly afew inches at a time when difficultyin transmitter loading is encoun-tered.
Note. The rf cable should be at rightangles to the antenna wires for the firstfew feet from the connection at the insu-lator. Lay the rf cable out as straight aspossible; do not allow the cable to formloops.
Figure 3. Typical packaging.
10
Figure 4. Use of tape measure to determine antenna wire length.
a. The following is a list of mainte-nance duties normally performed by theoperator of the antenna assembly. Spe-cial tools or test equipment is not re-quired.
b. Operator’s maintenance for the an-tenna assembly consists of the following:
DA Form 11-238 (fig. 8 and 9) is a pre-ventive maintenance checklist to be usedby the operator. Items not applicable to
Antenna Group AN/GRA-50 are lined outin the figures. Instructions for the useof the form appear on the form.
14. Operator's Visual Inspection
When the antenna assembly fails to op-erate properly, disconnect the radio setfrom the power source and check the items-
given below. Do not check any item withthe power on.
a. Inspect all electrical connections ofthe antenna assembly for tightness andcorrosion.
b. Inspect the insulator for cracks orchips and dirt.
14
TM
5820-467-15-8
15
Figure 9.
TM
5820-467-15-9
16
Section II. ORGANIZATIONAL AND FIELD MAINTENANCE (THIRD ECHELON)
15. Scope of Organizational Maintenance
The following is a list of maintenanceduties performed by organizational main-tenance personnel for the antenna assem-bly. The scope of these instructions hasbeen determined by the available tools,materials, test equipment, spare parts,and the MOS of the repairman.
a. Preventive maintenance (para 17).b. Troubleshooting (para 18).c. Replacement of parts (para 19).
16. Tools, Materials, and Test EquipmentRequired
A list of parts normally stocked for or-ganizational maintenance is contained inTM 11-5820-467-25P. The tools, mate-rials, and test equipment required for or-ganizational maintenance are listed below:
c. Test Equipment. M u l t i m e t e r A N /URM- 105.
17. Organizational Preventive Maintenance
DA Form 11-238 (fig. 8 and 9) is a pre-ventive maintenance checklist to be usedby organizational maintenance personnel.Items not applicable to the equipment arelined out in the figures. Instructions forthe use of the form appear on the form.
18. Troubleshooting
a. The troubleshooting chart is for useof second through fifth echelon mainte-nance personnel. Upon noting a defect ineither transmission or reception, shutdown the power at the transmitter/re-ceiver, disconnect the rf cable from thetransmitter/receiver antenna connector,and perform the appropriate procedurelisted in the chart below.
The only item of the antenna assembly b. Installation of Connector on End ofthat can be readily repaired is the rf cable Rf Cable.(b and c below). (1) Remove three-quarters of an inch
a. Tools and Test Equipment Required. of the rf cable outer jacket.
17
(2) Disassemble the UG-536/U and layout its parts in the order of dis-assembly.
(3) Slide the nut over the rf cable.(4) Slide the washer over the rf cable.(5) Slide the gasket over the rf cable,
one-sixth of an inch beyond the edgeof the rf cable outer jacket.
(6) Slide the flanged sleeve over thecopper braid shield.
(7) Flare the shield around the flangedsleeve.
(8) Remove the excess shield braid sothat it is even with the outer edgeof the flanged sleeve.
(9) Remove three-sixteenths of an inchof insulation from the end of theconductor.
(10) Slide the contact over the conductor
and solder through the hole in thecontact. File the soldered areasmooth.
(11) Insert the cable into the shell.(12) Tighten the nut securely. When the
cable and connector are properlyassembled, the contact tip shouldbe flush with, or not more than onethirty-second of an inch beneath theedge of the coupling.
(13) Use multimeter TS-352/U to checkthe rf cable for continuity andshorts.
c. Replacement of Cable RG58A/U.(1) Measure and cut off 75 feet of cable
(2) Install connector UG-536/U to eachend of cable RG-58A/U as in babove.
Figure 10. Cross section of rf cable and connector.
18
CHAPTER 4THEORY
20. Antenna Theory
The characteristics of transmitting andreceiving antennas are similar; a goodtransmitting antenna is also a good re-ceiving antenna.
a. Basic Half Wave Antenna. D u r i n gtransmission, the rf current in the antennawire produces a radiated field. During re-ception, a radiated field from a distantstation antenna cuts the antenna wire andcauses a current flow in the wire. In a halfwave antenna, current is maximum at thecenter and minimum at the ends, whilevoltage is minimum at the center and maxi-mum at the ends (fig. 11); therefore, im-pedance is minimum at the center andmaximum at the ends. The impedance atthe center of a basic half wave antenna is72 ohms. The current distribution in theantenna is the same regardless of theamount of current flow; the amplitudeof the current at any point on the antennavaries directly with the amplitude of thesignal voltage.
b. Directional Pattern.(1) Maximum radiation occurs at the
center of a half wave antenna, be-cause the current is greatest atthat point. Minimum radiation takesplace at the ends, because the cur-rent is least at the ends. Radiationis at right angles to the plane ofthe antenna wire and completelyencircles the antenna wire. Theresulting antenna directional pat-tern can be compared to a dough-nut with the radiator passingthrough its center. Figure 12 showsa cross section of the doughnutshaped pattern. Although there isno radiation along the direct line
(2)
of the antenna axis, there are dif-ferent amounts of radiation at dif-angles to the axis. There is littleradiation in direction OA, greaterradiation in direction OB, and max-imum radiation in direction OC.That part of the radiation fieldwhich travels upward, strikes theionosphere, and is returned at aconsiderable distance from theradiating antenna is called a sky-wave. A horizontal half wave an-tenna is very broadly bidirectionalin the horizontal plane. In practice,the antenna is oriented in the di-rection that provides maximumsignal strength.
21. Theory of Antenna Assembly
The antenna assembly is a horizontalcenter-fed Hertz antenna (doublet). A cen-ter-fed Hertz is one-half wavelength longat the operating frequency and is fed at itsphysical center. The antenna assembly isadjustable and can be used for operatingfrequencies from 1.5 to 20 mc. It consistsof two lengths of wire, each adjustable toa little less than a quarter wavelength atthe operating frequency. The transmissionline is a low-impedance coaxial cable thatconnects to the low-impedance point at thecenter of the antenna assembly. A certainamount of mismatch exists between therf cable and the antenna, but it is notcritical. Current and voltage distributionis the same as that described for a simplehalf wave antenna (para 20). The formulafor determining the actual total lengthof the antenna assembly required for aparticular operating frequency is:
Length in feet = 468Frequency in mc.
19
Figure 11. Current and voltage distribution in half wave antenna.
Figure 12. Radiation pattern of half wave antenna.
20
CHAPTER 5
SHIPMENT, LIMITED STORAGE, AND DEMOLITIONTO PREVENT ENEMY USE
Section 1. SHIPMENT AND LIMITED STORAGE
22. Disassembly (2) Coil the remainder of the cable.f. Coil and bind the halyards.
Warning: Disconnect the equipment fromthe power source before performing any 23. Repacking for Shipment or Limiteddisassembly.
Disassemble the antenna assembly asfollows:
a. The exact procedure used in packingfor shipment or limited storarge depends on
a. Disconnect the rf cable from the the material available and tie conditionstransmitter. under which the equipment is to be shipped
b. Release the tied ends of the halyards or stored. The information concerning theand lower the antenna slowly; be careful original packing (para 8) will be helpful.not to damage the insulator. b. Pack the equipment as follows:
c. Unfasten the antenna wire termina- (1)tions from the insulator and unfasten thereel assemblies from the halyards.
d. Wind the antenna wire onto each reel (2)assembly; use the index finger and thumbto help make a tight wind (fig. 6). (3)
e. Unfasten the rf cable connector fromthe insulator and coil the cable as follows: (4)
(1) Make one coil and tie the coil withfriction tape. (5)
Place the components in individualplastic bags and store them in BagBG-175.Enclose and seal Bag BG-175 in amoisture proof paper envelope.Place the enclosed Bag BG-175 ina suitable carton.Place pads inside the carton to holdBag BG-175 securely in place.Close and seal the carton with tape.
Section Il. DEMOLITION OF MATERIEL TO PREVENT ENEMY U S E
24. Authority for Demolition
The destruction procedures given inparagraph 25 will be used to prevent theenemy from using or salvaging this equip-ment. Demolition of the equipment will beaccomplished only upon the order of thecommander.
25. Methods of Destruction
Any or all of the following methods of de-struction may be used. The time availablewill usually be the most important factorto consider in deciding which methods willbe used, but the tactical situation must alsobe considered. If a number of antennas arein use in the same or nearby installations,
it is better to demolish completely thesame parts of all the antennas rather thanto partially damage all the antennas.
a. Smash. Use sledges, axes, crowbars,and any other heavy tools available. Firstsmash the reel assemblies then smash theinsulator and the rf cable connectors.
b. Cut. Use any available sharp tools tocut the rf cable, the antenna wires, and thehalyards in a number of places.
c. Burn. Burn as much of the equipmentas is flammable. Pour gasoline over theinstruction books, the rf cable, the insula-tor, and the halyards and ignite it.
d. Disposal. Bury or scatter all de-stroyed parts, or throw them into nearbywaterways.
21
APPENDIX IREFERENCES
Following is a list of applicable references that are available to the operator and unitrepairman of Antenna Group AN/GRA-50.
SB 38-100 Preservation, Packaging, and Packing Materials,Supplies, and Equipment Used by the Army.
TM 11-5820-295-10 Operator’s Manual: Radio Set AN/GRC-19.TM 11-5820-295-20 Organizational Maintenance: Radio Set AN/GRC-19.TM 11-5820-467-25P Organizational, Field and Depot Maintenance Repair
Parts and Special Tool Lists, Antenna Group AN/GRA-50.
22
APPENDIX II
BASIC ISSUE ITEMS LIST
Section I. INTRODUCTION
1. General
a. This appendix lists items supplied forinitial operation. The list includes tools,parts, and material issued as part of themajor end item. The list includes all items (3)
authorized for basic operator maintenance (4)
of the equipment. End items of equipmentare issued on the basis of allowances pre-scribed in equipment authorization tablesand other documents that are a basis forrequisitioning. (5)
b. The columns are as follows: (6)(1)
(2)
Source, maintenance, and recover- ability code. Not used. (7)Federal stock number. This col-umn lists the 11-digit Federalstock number. In the absence of aFederal stock number, an interim (8)number, for example L8Ra41C-12 in the description column, indi-
cates that a Federal stock numberis being processed for assignment.The L number may be used inemergencies to identify items.Designation by model. Not used.Description. Nomenclature or thestandard item name and brief iden-tifying data for each item are listedin this column. When requisition-ing, enter the nomenclature anddescription.Unit of issue. Not used.Expendability. Nonexpendableitems are indicated by NX.Quantity authorized. This columnlists the quantity of items suppliedfor the initial operation of theequipment.Illustrations. The "Figure No."column lists the figure for identi-fication of the items.
23
24
APPENDIX Ill
MAINTENANCE ALLOCATION
Section I. MAINTENANCE ALLOCATION
1. Generala. This section assigns maintenance
functions and repair operations to be per-formed by the lowest appropriate mainte-nance echelon.
b. Columns in the maintenance allo-cation chart are as follows:
(1)
(2)
Part or component. This columnshows only the nomenclature orstandard item name. Componentsand parts comprising a major enditem are listed alphabetically.Maintenance function. This columnindicates the various maintenancefunctions allocated to the echeloncapable of performing the opera-tions.
(a)
(b)
(c)
(d)
(e)
Service. To clean and to pre-serve.Inspect. To verify serviceabilityand to detect incipient elec-trical or mechanical failure byscrutiny.Test. To verify serviceabilityand to detect incipient electricalor mechanical failure by use ofspecial equipment such as gages,meters, etc.Replace. To substitute service-able assemblies and parts forunserviceable components.Repair. To restore an item toserviceable conditions throughcorrection of a specific failure orunserviceable condition. Thisfunction includes, but is notlimited to, inspecting, clean-ing, preserving, adjusting, re-placing, welding, riveting, andstraightening.
(3) 1st, 2nd, 3rd, 4th, 5th echelon. Thesymbol X indicates the echelon re-sponsible for performing that par-ticular maintenance operation, butdoes not necessarily indicate thatrepair parts will be stooked at that
(4)
level. Echelons higher than theechelon marked by X are author-ized to perform the indicatedoperation.Tools required. This column indi-cates codes assigned to eachindividual tool equipment, testequipment, and maintenance equip-ment referenced. The grouping ofcodes in this column of the mainte-nance allocation chart indicates thetool, test, and maintenance equip-ment required to perform themaintenance function.Remarks. Entries in this columnwill be utilized when necessary toclarify any of the data cited in thepreceding columns.
c. Columns in the allocation of tools formaintenance functions are as follows:
(5)
(1)
(2)
(3)
Tools required for maintenancefunctions. This column lists thetools, test, and maintenance equip-ment required to perform themaintenance functions.1st, 2d, 3d, 4th, 5th echelon. Thedagger symbol indicates theechelons allocated the facility.Tool code. This column lists thetool code assigned.
2. Maintenance by Using Organizations
When this equipment is used by signalservices organizations organic to theaterheadquarters or communications zones toprovide theater communications, thosemaintenance functions allocated up to andincluding fourth echelon are authorized tothe organization operating this equipment.
3. Mounting Hardware
The basic entries of the maintenance al-location chart do not include mountinghardware such as screws, nuts, bolts,washers, brackets, clamps, etc.
25
Section II.2
6
Section III.
27
By Order of Secretary of the Army:
Official:R. V. LEE,
Major General, United States Army,The Adjutant General.
NG: State AG (3) Units - Same as Active Army except allowance is one oopy to each unit.USAR: None.For explanation of abbreviations used, see AR 320-50.
28
U.S. GOVERNMENT PRINTING OFFICE : 1989 0 - 234-377
