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TM 11-5985-284-15D E P A R T M E N T O F T H E A R M Y T E C H N I C A L M A N U A L

OPERATOR, ORGANIZATIONAL,

DS, GS, AND DEPOT MAINTENANCEINCLUDING REPAIR PARTS

SPECIAL TOOLS LISTS

MANUAL

ANTENNA, LOOP AT-784/PRC( N S N 5 8 2 0 - 0 0 - 0 8 6 - 7 6 5 1 )

T h i s c o p y i s a r e p r i n t w h i c h i n c l u d e s c u r r e n t

p a g e s f r o m C h a n g e s 1 t h r o u g h 5 . T i t l ew a s c h a n g e d b y C h a n g e 5 .

H E A D Q U A R T E R S , D E P A R T M E N T O F T H E A R M Y

F E B R U A R Y 1 9 6 7

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*TM 11-5985-284-15

T E C H N I C A L M A N U A L H E A D Q U A R T E R S

D E P A R T M E N T O F T H E A R M YN o . 1 1 - 5 9 8 5 - 2 8 4 - 1 5 W A S H I N G T O N , DC, 3 F e b r u a r y

C H A P T E R 1 .Section I.

I I .


I I .

II .

Operator s , Organiza t ional , Direc t Suppor t r G e n e r a l S u p p o r tand Depo t Ma in t enance Manua l

ANTENNA , LOOP AT- 784/ PRC(NSN 5820-00-086-7651)

ParagraphINTRODUCTIONGeneralScope - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -- - - - - - - - - - - - - - - - - - - - - - - - - - - - - 1-1Indexes of publications - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -1-2Forms and Records - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 1-3Reporting of errors - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 1-3.2Reportin g equipm ent impr ovement recomme nda tions (EIR) - - - - - - - - - - - - - - - - - - - -- - - 1-3.3Des tr uct ion of Arm y elect ron ics m at er ial - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 1-3.3Description and DataPurpose and use - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 1-4Te c h n i c a l c h a r a c t e r i s t i c s - - - - - - - - - - - - - - - - - - - -- - - - - - - - - - - - - - - - - -- - - - - - - - - - - - 1 - 5Comp onen ts of Ant en na , Loop AT-784/PRC - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 1-6Items comprising an operable Antenna Loop AT-784/PRC - - - - - - - - - - - - - - - - - - - - - 1-6.1Des cript ion of Ant en na AT-1082/PR C - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 1-7Des cript ion of as sociat ed com pone nt s - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 1-8Additional equipment required - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 1-9INSTALLATION AND OPERATION INSTRUCTIONSService Upon Receipt of Antenna, Loop AT-784/PRCUn pa cking - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 2-1Checking unpacked equipment - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 2-2Installation - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -- 2-3Si t in g - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 2-4Antenna Contro lsControls and their uses - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 2-5Cont rols an d a nt enn as - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 2-6Operation Under Usual ConditionsGeneral - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -- - - - - - - - - - - - - - - - -- - 2-7Operation - - - - -- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 2-8Operation Under Unusual ConditionsGener a l - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -- - - - - - - - - - - 2-9Operation in arctic climates - -- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 2-10Operation in desert climates - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 2-11OPE RATORS AND ORGANIZATIONAL MAINTEN ANCE IN STRUCTION SOpera t or s Maint enan ceScope of operators maintenance - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 3-1Preventive maintenance - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 3-2Pr event ive ma int ena nce checks an d ser vice periods - - - - - - - - - - - - - - - - - - - - - - - - - - - - 3-3Daily preventive maintenance checks and services chart - - - - - - - - - - - - - - - - - - - - - - 3-4Weekly preventive maintenance checks and services chart -- - - - - - - - - - - - - - - - - - - 3-5

Cle anin g - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 3-6Organiza t ional MaintenanceScope of organizational maintenance - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 3-7Mont hly p re ven tive ma int en an ce - - - - - - - - - - - - - - - -- - - - - - - - - - - - - - - - - - 3-8Monthly preventive maintenance checks and services charts - - - - - - - - - - - 3-9Touchup painting - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 3-10Rep la cem en t of pa rt s - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 3-11

*This ma nua l supersede s TM 115820-496-20P, 13 Ma rch 1964, and TM 11-5820- 496-35P, 24 July 1963.

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I I I .

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C H A P T E R 3 .S e c t i o n I .

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C H A P T E R 4 ,Section I.

Section II.


II .

C H A P T E R 6 .

C H A P T E R 7 .

Section I.

II .

A P P E N D I X A .

A P P E N D I X B .Section I.II .

A P P E N D I X C .Section I.

II .I I I .IV.

ParagraphDIRECT SUPPORT MAINTENANCEFunct ioning of EquipmentScop e ---------------------------------------------------------------------------------------------------------------- -- 4-1Antennas ----------------------------------------------------------------------------------------------------------- -- 4-2Direction finder antennas -------------------------------------------------------------------------------- - 4-3Antenna AT-1082/PRC --------------------------------------------------------------------------------------- - 4-4Direct Support Troubleshooting and RepairOrganization of troubleshooting ----------------------------------------------------------------------- -- 4-5Test equipment required --------------------------------------------------------------------------------- -- 4-6Res ist an ce me as u re men t s ---------------------------------------------------------------------------------- -- 4-7Troubleshooting chart ---------------------------------------------------------------------------------------- -- 4-8Rep a ir s -------------------------------------------------------------------------------------------------------------- -- 4-9Removal and replacement of chassis and components ------------------------------------- - 4-10Replacement of loop antenna arms ----------------------------------------------------------------- -- 4-11GENERAL SUPPORT MAINTENANCERepair and AlinementRep a ir ---------------------------------------------------------------------------------------------------------------- -- 5-1Frequency range alinement procedures ------------------------------------------------------------- -- 5-2General Support Testing ProceduresGen er a l -------------------------------------------------------------------------------------------------------------- --- 5-3Tes t equ ipm en t r equ ir ed ------------------------------------------------------------------------------------- -- 5-4Test conditions --------------------------------------------------------------------------------------------------- -- 5-5Physical tests and inspection ------------------------------------------------------------------------------ -- 5-6

Fr equ en cy ra nge t es t ------------------------------------------------------------------------------------------ -- 5-7Sensitivity, attenuation, null, and sense tests ------------------------------------------------------ -- 5-8DEPOT OVERHAUL STANDARDSScope ----------------------------------------------------------------------------------------------------------------- -- 6-1Depot overhaul standards ------------------------------------------------------------------------------ - 6-2SHIPMENT AND LIMITED STORAGE AND DEMOLITION TO PREVENT

ENEMY USEShipment and Limited StorageDisassembly ----------------------------------------------------------------------------------------------------- -- 7-1Repacking for shipment or limited storage --------------------------------------------------- -- 7-2Demolition of Materiel to Prevent Enemy UseAut hori t y for dem olit ion ------------------------------------------------------------------------------------ -- 7-3Met hod s of de st ru cti on ------------------------------------------------------------------------------------- -- 7-4REFERENCES ------------------------------------------------------------------------------------------------------

BASIC ISSUE ITEMS LISTIn t rodu ction -----------------------------------------------------------------------------------------------------------Basic issue items list ------------------------------------------------------------------------------------------------MAINTENANCE ALLOCATIONIn t rodu ction -----------------------------------------------------------------------------------------------------------Maintenance allocation chart -----------------------------------------------------------------------------------Tool and tast equipment requirements ------------------------------------------------------------------Rem arks ----------------------------------------------------------------------------------------------------------------

Page

4-14-14-14-3

4-7

4-74-74-7

4-104-104-10

5-15-1

5-25-25-25-2

FoldoutFoldout

6-16-1

7-17-1

7-171

A-1

B-1B-1

C-1C-3C-4C-5

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CHAPTER 1INTRODUCTION

Section I. GENERAL1-1. Sc ope

a. This manual describes the components of Antenna, Loop AT-784/PRC (fig. 1-1 ), and coversth eir use, opera tor s ma intena nce, organiza-tiona l ma intena nce, and basic fun ctioning. Italso contains the repair functions for thisequipment which are to be accomplished bydirect support, general support (DS and GS) anddepot maintenance.

b. Throughout th is manua l, the term sensewhip antenna refers to the telescoping portion of Antenna AT-1082/PRC and loop refers to theloop antenna in which the telescoping antennais mounted.

1-2. In dexes 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 modification work orders (MWOs) perta ining t o the equipm ent .

1-3. Ma intenance Forms, Records, andReports

a. Reports of Maintenance and Unsatisfac-

tory Equipment. Department of the Army formsand procedures used for equipment mainte-nance will be those prescribed by TM 38-750, TheArmy Maintenance Management System(TAMMS).

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 DLAR 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 4610.33B/ AFR 75-18/MCO P4610.19C and DLAR 4500.15.

1-3.1. Reporting Errors and Recom-mending Improvements

You can help improve this manual. If you findany mistakes or if you know of a way to improvethe procedures, please let us know. Mail yourletter or DA Form 2028 (Recommended Changesto Publications and Blank Forms) direct to:Commander, US Army Communications andElectronics Materiel Readiness Command,

ATTN: DRSEL-ME-MQ, Fort Monmouth, NJ07703.

1-3.2 Re porting Equipment ImprovementRecommendations (EIR)

If your Antenna, Loop AT-784/PRC needsimprovement, let us know. Send us an EIR. You,the u ser, are t he only one who can tell us whatyou dont like about your equ ipmen t. Let usknow why you dont like the design. Tell us whya procedure is hard to perform. Put it on an SF368 (Quality Deficiency Report). Mail it to

Commander, US Army Communications andElectronics Materiel Readiness Command,ATTN: DRSEL-ME-MQ, Fort Monmout h, NJ07703. Well send you a reply.

1-3.3. De struction of Army ElectronicsMateriel

Destruction of Army electronics materiel toprevent enemy use shall be in accordance withTM 750-244-2.

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Figure 1-1.

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Figure 1-2.

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Section Il. DESCRIPTION AND DATA

1-4. Pu rpose and Useu. Purpose. Antenna, Loop AT-784/PRC, when

used in conjunction with Radio Set AN/PRC-25,AN/VRG-12, or their equivalents, comprises ahoming device that enables the operator to findthe direction of a transmitted signal within thefrequency range of 30 to 76 MegaHertz (MHz).

CAUTION

Use the AT-784/PRC for reception only.Do not transmit. Whenever the loop

its extendable sense whip antenna (fig. 1- 2) is

antenna is not in use, keep the AT-TENUATOR switch set to 0.

The u nsh ielded loop an tenn a of Ant enna AT-1082/PRC is used to pick up a homing signal, and

used to determine the direction of the transmit-ted signal. The AT-1082/PRC is not providedwith a n azimuth indicator, since highly accu-rate bearings are not generally required for

homing purposes. A pocket compass can be usedto provide approximate azimuth readings bysighting in the direction of the indicated bear-ing.

1-5. Te chnical CharacteristicsFrequency range . . . . . . . ..30 to 76 MHz covered

in five ban ds.Frequency bands . . . . . . . ..(1) 3040 MHz.

(2) 40-50 MHz.(3) 50-60 MHz.

(4) 60-70 MHz.(5) 70-76 MHz.Fine tuning

range . . . . . . . . . . . . . . . . .. 0-10 MHz covered in1-MHz steps.

Signal at tenua-tion . . . . . . . . . . . . . . . . . . .. 0-46 dB covered in

five step: 0, 10,20, 30, and 40 dB.

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1-6. C omponents of Antenna, Loop AT-784/PRC(Fig. 1- 1)

The components of Antenna, Loop AT-784/PRV,are listed in the following table:

Quant i ty

11

1

1

Item

Antenna AT-1082/PRCBag, Cotton Duck CW-445/PRCCable Assembly, Radio Frequency

CG-3344/PRC (5-ft).Cable Assembly, Radio Frequency

CG-2840A/U (12 ft).

Height(in.)

*7

8

Depth(in.)

Width Unit(in.) weight

(lb)

4 2

6 0.9

Refers to the height with the sense whip antenna retracted and the loop antenna turned down.

1-6.1. ite ms Comprising an Operable Antenna, Loop AT/784/PRC

NSN

5820-00-086-7651

5985-00-889-39215995-00-933-98625985-00-937-16305995-00-933-8961

Quantity

1

1

1

1

1

Nomenclature, part No., and mfr code

NOTEThe part number is followed by the applicable 5-digit Federalsupply code for manufacturers (FSCM) identified in SB 708-42and used to identify manufacturer, distributor, or Governmentagency, etc.

Antenna, Loop AT-784/PRCwhich includes:

Antenna AT-1082/PRC: MIL-A-55138, 80063Cable Assem bly, RF, CG-3344/PRC: SM-D-5088884, 80063Cap, E lectrical, CW-922/GRC: SC-DL-508885, 80063Cable Assem bly RF, CG-2840 A/U: SM-D-508886, 80063

Fig. No.

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1-7. De scr ip t ion of Ant enna AT-1082/PRC(fig . 1-2)

Antenna AT-1082/PRC is a compact, portableunit that is housed in a cast aluminum case. Aloop antenna is mounted on top of the caseand it has an expendable sense whip antennawithin its left side. The case is shaped to beeas i ly hand held land serves to protect the

antenna assembly when it is folded down andto protect i t s panel controls f rom accidenta ldamage by dropping. The grooved rear coverof this case allows access to the componentsand provides a water t ight inclosure . An in-s t r u c t i o n l a b e l t h a t c o n t a i n s c o n d e n s e doperating instructions (fig. 2-3 ) is secured tothe cover. The control sof the AT-1082/PRCinclude a bandswitch, a f ine tuning control ,and an attenuation control switch.

1-8. De s c r i p t i o n o f A s s o c i a t e d C o m p o n e n t s

T h e m i n o r c o m p o n e n t s o f A n t e n n a , L o o pAT-784/PRC, which are associated with An-tenna AT-1082/PRC, are shown in figure 1-1and are described below:

a . C a b l e A s s e m b l y , R a d i o F r e q u e n c yCG-3344/ PRC (5-Ft). This is a 5-foot cable in-

C 2, TM 11-5985-284-15

eluding Cap, Electrical CW-922/GRC (shieldcap) , for the large antenna post of the as-sociated radio receiver, attached by cord. It isu s e d t o c o n n e c t AT- 1 0 8 2 / P R C t o t h e a s -sociated receiving set.

b . C a b l e A s s e m b l y, R a d i o F r e q u e n c yCG-2840 A/ U (12-Ft). This is a 12-foot cablethat is provided for extending the cable con-

nection of the AT-1082/PRC to a receiving setwhenever required.c. Bag, Cotton Duck CW-445/ PRC. This bag

i s fo r c a r r y i n g a n d s t o r i n g An t e n n aAT-1082/PRC, a shield cap for its output con-nector, and the two associated cables. Mois-ture and fungus resistant cotton duck mater-ial is used for the construction of this bag.

1-9. Ad di t iona l Equipment Requi red

Radio Set AN/PRC-25, AN/VRC-12, or equi-valent , i s not suppl ied wi th Antenna, LoopAT-784/PRC; however, one of similar type isrequired f o r u s e o f t h i s a n t e n n a . F o r example : Radio Set AN/PRC-25, which is amanpack receiver- t ransmit ter, i s capable of r ece iv ing inpu t s igna l s ove r the f r equencyrange of 30 to 76 MHz.

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INSTALLATIO N

CHAPTER 2

AND OPERATION

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INSTRUCTIONS

Sect ion I . SERVICE UPON RECEIPT OF ANTENNA LOOK AT-784/PRC

2-1. U npack ing

a. Packaging Data. When packed for ship-ment , the components compris ing Antenna,Loop AT-784/PRC, are placed in a corrugatedcardboard car ton. A typical shipping car tonand its contents is shown in figure 2-1. Th edimensions of the carton are 10 by 6 by 5inches.

b. Removing Contents . To unpack, proceedas follows: Open the carton, lift out Bag, Cot-ton Duck CW-445/PRC, remove i ts contents ,and check the components (para 2-2 , and para1-6.1).

NOTE

Save the or iginal packing car ton. I tcan be used aga in when the equ ip-m e n t i s r e p a c k e d f o r s t o r a g e o rsh ipment .

2-2. Ch eck ing Unpacked Equ ipmen t

a. Inspect all equipment for damage possi-bly incurred during shipment . I f the equip-ment has been damaged , repor t the damageon DD Form 6 (para 1-3 b).

b. See tha t the equ ipment i s comple te aslisted on the packing slip, or paragraph 1-6.1.Report a l l d iscrepancies in accordance withAR 735-11-2. Shortage of a minor assembly orpart that does not affect proper functioning of the AT-1082/PRC should not prevent use of the equ ipment .

2-3. I n s t a l l a t i on

To install Antenna AT-1082/PRC, follow theprocedures in a through e below.

a. R e m o v e t h e AT- 1 0 8 2 / P R C f r o m t h eCW-445/PRC (carrying bag).

Figure 2-1. Packaging of Antenna, Loop AT-784/ PRC.

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C2, TM 11-5985-284-15

b. P l a c e t h e l o o p a n t e n n a i n t o o p e r a t i n gposition as shown in figure 2-3.

c. Con n e ct c o n n e c t o r J 1 of t h eAT-1082/PRC to the antenna coaxial connec-tor of the radio set with which it is to be usedby the CG-3344/PRC cable. The 12-foot cable( C G - 2 8 4 0 A / U ) m a y b e a d d e d t o t h eCG-3344/PRC to increase the interconnectioncable length, if required.

d . R e m o v e a l l o t h e r a n t e n n a s f r o m t h eradio.

e. T h e sh ield cap a t t a c h e d t o t h eCG-3344/PRC (f ig. 1-1) is provided for usewi th Rece ive r-Transmi t t e r s , Rad io RT-505 / PRC-25 (part of Radio Sets AN/PRC-25 andA N / V R C - 5 3 ) a n d RT- 8 4 1 / P R C - 7 7 ( p a r t o f Rad io Se t AN/PRC-77) . On these rece ive r-transmitters, press the shield cap down as faras it will go over the whip antenna base. Theinside top of the shield cap should contact the

top of the whip antenna base on the radio and

ground it to the radio set chassis. When theradio set whip antenna base is not grounded,it interferes with homing signals.

2-4. S i t ing(fig. 2- 2)

The best performance of Antenna AT-1082/ PRC is obtained when it is used over an unob-structed line-of-sight path with a compatibleradio set. For this reason, the AT-1082/PRCshould be operated away from obstruct ionssuch as large buildings, bridges, steel struc-tures, and hills. These objects will block ordef lect the desired s ignal , thereby makinghoming d i ff i cu l t o r imposs ib le . Also , th i se q u i p m e n t s h o u l d n o t b e o p e r a t e d n e a rhigh-power or telephone lines. The best sitesfor desired directional looping are on hilltopsor over open, f la t terra in . F igure 2-2 il lus-t r a tes typ ica l good and poor loca t ions fo r

AT-1082/PRC operation.

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Figure 2-2. Using AT-1082/PRC in good and bad operating areas.

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Figure 2-3.

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Section Il. ANTENNA CONTROLS

2-5. Co ntrols and Their UsesAll operating controls of Antenna AT-1082/

PRC are listed in paragraph 2-6 and are Shownin figure 2-3. Care should be taken not to forcecontrols since damage to switch contacts mayresult.

2-6. Co ntrols and Antennas

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Control or antenna

Loop antenna - - - - - - -

Func t ion

When extended, receives radio wavesfor transmission through the AT-1082/PRC to the associated receiver.When s i t ua t ed b r o a d s ide t o t het r ans mi t t ed s i gna l , t h e s i gna l i sa t tenuated (nul l condi t ion) ; con-versely, when situated so that theedges of the loop face the trans-mi t ted s ignal , the s ignal i s nota t tenuated .

Control or antenna

Sense whipantenna .

TM 11-5985-284-15

Func t ion

When extended and in conjunct ionwith the loop antenna having theo p p o s i t e e d g e o f t h e l o o p a n -tenna facing the transmitted signal,d e - t e r m i n e s ( s e n s e s ) t h e d i r e c -t i o n f r o m w h i c h t h e s i g n a l i st ransmit ted .

Section Ill. OPERATION UNDER USUAL CONDITIONS

Caution 1: Use the AT-784/PRC for recep-tion only. Do not transmit when the AT-784/ PRC is connected to the radio set; remove allother antennas from t he radio set.

Caution 2: Keep the ATTENUATOR switchto O whenever the AT-1082/PRC is not in use.

2-7. G enerala. Modulated and Unmodulated Carrier. Di-

rection finding of, or homing-in on, a transmittingstation is accomplished by d etecting its mod ulatedor unmodulated carrier. Usually, it is better tohome-in on the unmodulated carrier signal than avoice or test tone; the test tone or v oice is best usedwhen the transmitting signal is somewhat distantfrom the AT-1082/ PRC. When th e transm itting

site is nearby, with the carrier modulated or un-modulated, it is better to follow the carrier indica-tion rather than the modulation feature.

(1) Modu lated carrier. Modulat ion of thetransmitter carrier frequency occurs wh envoice, music, test tone, etc., are trans-mitted.

(2) Unmodulated carrier. This action oc-curs when the transmitter is turned on butthe carrier frequency is not mod ulated byvoice, music, test tone, etc. On ampli-tude modulation transmission (am), the

transmitter is detected by the quieting of the noise when tile receiver is turned inthe area of the transmitter frequency.On frequency modulation (fm) trans-mission, the tran smitter is detected by th elessening or stopping of the rushing noise

when the receiver is tuned to the area of tile transmitter frequency.

b. Maximum Signal. The te rms maximumsignal an d maximum are used to define the posi-

tion of the loop antenn a. when it is so oriented th atthe greatest signal response (maximum signal) isheard in the receiver. This occurs when the sensewhip antenna is extended for sensing (d below)At this time, a greater response is obtained on thereceiver when that edge of the loop antenna op-posite the edge in which the sense whip antennais mounted faces the transmitter. When the sensewhip antenna is retracted, signals of equal inten-sity are obtained from either edge of the loopantenna.

c. Null Signal. The terms null position a n

null are used to define tile position in which theloop antenna is oriented when minimum or no sig-nal response is heard on the receiver. This occurswhen either broadside of the loop antenn a is facingthe transmitting station. The two nulls are de-fined properly when the sense whip antenna is re-tracted. The null gives a sharper or more ac-curate indication than the ma ximu m sense position(d below). Consider the loop antenna as an en-larged gun-sighting device; it is necessary to loothrough the hole formed by the loop antenna to-ward the transmitting station. This will be thesame direction as the maximum signal from theedge of the loop antenna (d below). In the pres-ence of a strong signal, the null will be moreclearly defined and quite narrow; the rotation of a few degrees will produce sharp variations inthe received signal. On a weaker signal, the width

2 -

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of th e nu ll may increas e to 30 or 40 O. The centerof the null (or area) is the correct bearing.

d. Sensing. Because there are two nulls, thenu ll indication does not pr ovide sufficient inform a-tion for the operator to determine whether thetransmitting source is in front of, or behind, theloop antenna. To find t he a ctua l direction of th etr ansm itting sour ce, a nu ll is detected, the sense

whip antenna is extended, and the loop antenna ist u r n e d s id ew a ys t o t h e t r a n s m i t t i n g s ig n a l.When the signal is loudest in the receiver, theSIGNAL MAX arrow on the top of the case (fig.2-3) will point in the direction of (sense) thetransmitting signal.

e. Hom ing. Homing is the procedure of detect-ing a transmitting station and approaching it .The general procedure is as follows:

(1)(2)

(3)

(4)

Find the null.Determine the sense and ta ke a bear ingon th e tran smitting stat ion as indicat edby the SIGNAL MAX arrow on the topof th e case (fig. 2-3 ).When the direction of the transmittingstation is determined, the sense whip an-tenna is retracted, the loop antenna isturned broadside to the transmitting sta-tion, and the null indication is detected onthe receiver. If the null is particularlybroad, rota te th e loop antenn a back andforth a few times. Select the center of the n ull , and proceed on a l ine t hroughth e center of the nu ll unt il the tr ansm it-ting station is reached.As the transmitter is approached, succes-sive bearings can be taken with increasedaccuracy because of the narrowing nullarea which results from increased signalstrength.

f. Attenuation.

C a u t i o n : Wh e n e v e r t h e l o op a n t e n n a i s n o ti n u s e , k e e p t h e AT T E N UAT O R s w i t c h a t 0 .

(1)

2- 6

Very strong signals may have a tendencyto obscure th e nu ll and sense indication.In general, such signals will be found

close to the transmitter. If the hea ringsare obscured an d the tra nsmitt er cann otbe seen, advance the ATTENUATORswitch t o position 1, 2, 3, or 4 to r educethe signal strength to the point, wherethe null becomes clear.

(2) Positions 1, 2, 3, and 4 provide increas-ing and marked differences in attenua-tion. The position of least attenuationthat permits sense and bearing determi-nation should be used. operat ion inATTENUATOR position 4 is not nor-mally used except in the immediate vicin-ity of the transmitting station (within

100 to 200 yards depending on the ter-rain). An accurate sense indication willbe difficult, to obtain in this position, butthis condition should not present anyoperating difficulties since the general di-rection of travel has been previouslyestablished and th e null bearing shouldbe sufficient for transmitter location.

2-8. Op era t ion

The operating procedure of Antenna AT-1082/ PRC for homing-in on a modulated or unmodu-

lated carrier is described below. On the receiver,the greatest, signal response (maximum signal)for a modulated carrier is indicated by a loudaudio output ; for an unmodulated carrier, theindication is indicated by maximum receiverquieting.

a. Preliminary.(1) Check to see that the AT-1082/PRC is

(2)

connected to the receiver (para 2- 3).Remove all other antennas from the re-ceiver. Set the ATTENUATOR con-trol to 0.

On the receiver, tune to the operatingfrequency, set the volume control formaximum loudness, and set the squelchcontrol to off when there is such aprovision.

b. Procedure.

(1) Unfold the loop antenna, and set the

(2)

BANDSWITCH and FINE TUNE con-trols to the positions that are closest tothe frequency setting on the receiver.For exam ple, to tune to 45.80 MHz, set

the BANDSWITCH control to 40 andthe FINE TUNE control to 5.

Hold the AT-1082/PRC vertically (fig.2-2), and rotate it clockwise and counter-clockwise for maximum signal indicationon t h e r eceive r. R ea d ju s t t h e F I N E

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fig. 2-2

(3)

(4:

TUNE control for a greater output sig-nal on the receiver. A maximum signalindication will be indicated by a loud (b )audio output on the receiver because of a m odulated carrier or by maximum re-ceiver quieting because of an unmodu-lated carrier.

C a u t i o n : D o n o t u s e t h e F I N ET U N E c o n t r o l s e t t i n g a s a s t a n d a r d i nd e t e r m i n i n g t h e t r a n s m i t t e r f r e -quency.

Adjust the ATTENUATOR control forcomfortable audio output from the re-ceiver. At this point, the AT-1082/PRCloop an tenn a is oriented edgewise to th etransmitting source.To determine the direction of the signalsource, proceed as follows: (5)

(a ) Rota te t he loop an tenn a 90 to obtain

a null indication on the receiver. Theloop antenna is now broadside to the (6)signal source and is indicated by theSIGNAL NULL arrows on the signal

2-9. G enera l

TM 11-5985-284-15

direct ion label on top of the case(fig. 2-3 ).Extend the sense whip antenna. Thisaction will cause a signal output fromth e receiver. Star ting with th e broad-side position ( (a) above), listen for themaximum output signal while rotatingthe loop antenna clockwise and then

counterclockwise from the broadsideposi t ion. Set the AT-1082/PRC tothe position tha t provides the st rongestsignal indication in the receiver. Theloop ant enna is again in line with th etra nsmitt ing signal source, an d th e sig-nal source is in the direction away fromthe sense whip antenna, as indicatedby the SIGNAL MAX arrow on thesignal direction label. (* See below

Retract the sense whip antenna, and,using the loop an tenn a, home-in on the

signal source with the null indication.Adjust the ATTENUATOR control fora comfortable listening level of the re-ceived signal.

Sect ion IV. OPERATION UNDER UNUSUAL CONDITIONS

Operation of Antenna AT-1082/PRC may bedifficult in r egions wh ere extr eme cold, heat , hu-midity and moisture, sand conditions, etc., pre-

vail. In paragraphs 2-10 and 2-11, instructionsar e given on procedur es for m inimizing t he effectof unusual operating conditions.

2-10. Op e r a t i o n i n A r c t i c C l i m a t e s

Subzero temperatures and climatic conditionsassociated with cold weather affect the efficientoperation of this equipment. Instructions andprecautions for AT-1082/PRC operation undersuch adverse conditions are as follows:

a. Handle the equipment carefully.b. Keep the equipment warm and dry.c. Keep frost or ice from accumulating on the

loop frame; such accumulations will prevent theloop from being opened or closed and will preventthe sense whip antenna from being extended orretracted.

d . Moisture will condense on equipment thathas been exposed to the cold and is brought into awarm room; it will continue to do so until roomtempera tu re i s r eached . Th is condi t ion a l so

arises when equipment war ms up during the dayafter exposure during a cold night. When theequipment has reached room temperature dry itthoroughly.

2-11. Op e r a t i o n i n D e s e r t Cl i m a t e s

The ma in problem when operat ing this equip-ment in desert a reas is the large amount of sandor dust and dirt which enters its moving parts.Therefore , Antenna AT-1082/PRC should bestored in dust proof cent ainers when it is n ot in

use. When using this equipment, keep it as freefrom dust and sand as possible. Excessive accu-mulation of sand, dust, or dirt on the loop framewill prevent the sense whip antenna from beingextended or retracted as required.

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Paragraph 3-4 Paragraph 3-5

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CHAPTER 3

OPERATORS AND ORGANIZATIONAL MAINTENANCE INSTRUCTIONS

Section I. OPERATORS MAINTENANCE

3-1. Sc ope of Operators Maintenance

The maint enance duties assigned to the operatorof Antenna, Loop AT-784/PRC, are listed below,together with references to the paragraphs cover-ing the specific maintenance functions. The dutiesassigned do not require t ools or test equipment,but two radio sets (AN/PRC-25, or equivalent)are required for operational checkout: One fortransmitting purpose and one for receiving AT-1082/PRC outputs.

a. Preventive maintenance ( para 3-2 ).

b. Preventive ma intenan ce checks and serviceperiods (para 3-2 ).

c. Daily preventive maintenance checks andservices chart (para 3- 4).

d . Weekly preventive maintenance checks andservices chart ( para 3-5 ).

e. Cleaning ( para 3-6 ).

3-2. Pr eventive Maintenance

Pr eventive maint enan ce is the systemat ic care,servicing, and inspection of equipment to prevent

the occurrence of trouble, to reduce downtime, andto make sure that, Antenna, Loop AT-784/PRC, isin a combat serviceable condition at all times.Because of moisture and fungus growth, t he m ain-tenance of this antenna in tropical climates is moredifficult than under temperate climatic conditions.The high relative humidity causes condensationto form on the equipment; this is especially truewhen temperature of the equipment becomes lowerthan the surrounding air. To minimize this con-dition, keep this type of antenna sheltered and off the ground as much as possible.

a. Systematic Care. The procedures given inparagraphs 3-4 through 3-6 cover routine careand cleaning essential to proper upkeep andoperation of the equipment.

b. Preventive Maintenance Checks and Services.The preventive maintenance checks and serviceschar ts (paras 3-4 an d 3-5) outline fun ctions t o beperformed a t specific int ervals. 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 charts indicatewhat 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 th edefect cannot be remedied by the operator, highercategory maintenance or r epa ir is required.Records and reports of these checks and servicesmust be made in accordance with the requirementsset forth in TM 38-750.

3-3. Pr eventive Maintenance Checks and

Service Periods

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3-4. Da ily Preventive

Sequence

10

11

3 - 2

Item to be inspected

AT-1082/PRC, sensewhip antenna.

AT-1082/PRC, loopantenna .

AT-1082/PRC, con-

trols.

Ca bles . . . . . . . . . . . . .

Connections . . . .

Controls . . . . . . .

Antenna parts . . . . . . .

CG3344/PRC (5-ft) . . .

CG-2840A/U (12-ft) . . . .

AT-1082/PRC

AT-1082/PRC. con-trols and antennas.

Maintenance Checks and Services Chart

Procedure

Inspect for bends and distortion - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

Check to see that loop antenna, opens to operating position with-out, binding.

Observe effect on signal during operating procedures . . . . . . . . . . .

a .b.

Inspect for damaged connectors. . . . . . . . . . . . . . . . . . . . . . . . . . .Check for tight connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

All antenna and cable connect ions should be f inger t ight . Check and t ighten when necessary.

Check to see that the mechanical action of each control is smoothand free of external or internal binding.

a .

b.

c.

d.a.

b.c.

a.

b.c.

a.

b.

c.

Check to see that the loop antenna can be easily placed into itsoperating position and that it locks in its detented position.

Check to see that the sense whip antenna can be extended i tsfull height (12 inches) and remain there.

Check to see that the sense whip antenna and loop antenna maybe returned, respectively, to their nonactive positions

Check to see that the shield cap is attached to the CG-3344/PRC.Connect the cable to the radio receiver and the AT-1082/PRC;

if applicable, attach the shield cap to the radio antenna con-nector.

Check th e connections for tigh tn ess - - - - - - - - - - - - - - - - - - - - - - - -Check the shield cap for snug fit on the antenna connector of the

radio and for connection to the CG3344/PRC.Connect the CG-2840A/U between the CG-3344/PRC and the

radio receiver.Check the connections for tightness - - - - - - - - - - - - - - - - - - - - - - - - - - - -Continue to the operational checks - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

Make all transmission and reception arrangements with a dis-tant radio transmitter before connecting the AT-1082/PRCto the rece ivcr. Note the d i rec t ion of the t ransmi t te r.Arrange with the distant transmitt ing station to turn on i tstransmitter long enough to make the AT-1082/PRC tests.

T O start the test , set the transmit and receive frequency to 30MHz. If the tactical situation will not permit this arrange-ment, use the assigned operating frequency.

C a u t i o n : Do not transmit from the radio set connected to theAT-1082/PRC; damage to the equipment may result.On the receive radio set, make the following adjustments:

(1) Set the volume control for maximum signal output.(2) set the squelch control, if provided, to off.

a.

b.

Set ATTENUATOR to 0; BANDSWITCH to 30 (or to position

corresponding to assigned operating frequency); and FINETUNE to 0 (or to position corresponding to assigned operatingfrequency);

Set the loop antenna in operating posit ion and extend the sensewhip antenna.

References

Sequence num -

bers 5 through20 below.

a. None.b. Sequence

numbers 7and 8below.

Para 2-3.

Fig. 2-3 , para2-6.

a . Fig. 2-3.

b. Same as aabove.

c. Same as aabove.

d. Fig. 1-1.a . Para 2-3 , fig.

1-1.

b. None.c. Same as a

above.a . Fig. 1-1.

b. None.c. Sequence

numbers 11through 20

below.

Para 2-6 an d

sequence No.10 above.

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1 2

1 3

1 4

1 5

1 6

1 7

1 8

19

2 0


AT-108 2/ PRC - - - - - -

AT-1082/ PRC,ATTENUATORcontrol.

AT-108 2/ PRC, FINETUNE control.

AT-1082/ PRC,BANDSWITCHcontrol.

AT-1082/PRC, nullposition.

AT-1082/PRC,BANDSWITCH a ndFINE TUNE con-trols (45 MHz).

AT-1082/PRC,B AN DSWIT CH andFINE TUNE con-trols (55 MHz).

AT-1082/PRC,B AN DSWIT CH a ndFINE TUNE con-trols (6.5 MHz).

AT-1082/PRC,B A N D S W I T C Ha n d F I N E T U N Econtrols (75 MHz).

Procedure

a.

b.

c.a.

b.

a.

b.

a.

b.

a.

b.

a .

h.

c.

a.b.

c.

a.

b.

c.

a.

b.

c.

Position the loop antenna so that the SIGNAL MAX arrow onthe signal direction label is toward the transmitting station.Note the level of the received signal.

Rotate the loop antenna 180. The received signal should belower.

Set the loop antenna in the original position (a above).

Turn ATTENUATOR control to positions 1, 2, 3, and 4. Ateach position, signal level should be lower.

Set the ATTENUATOR control for a comfortable listening levelon receiver.

Rotate the FINE TUNE control to each of its other positions.Received signal level should be lower as contr ol is moved a wayfrom the original setting.

Reset the FINE TUNE control to original position.Rotate the BANDSWITCH control to each of its other posi-

tions; no signal is received on the receiver in the other positions.Reset to the original position.Retract the sense whip antenna.

Rotate the loop antenna 90; it is now broadside to the trans-

mitting station. The received signal level should lessen orthe signal should disappear.

Note. If the tactical situation permits use of other frequencies, use the pro-cedures given in sequence numbers 17 through 20 below, to test the operation of the AT-1082/PRC in 40-, 50-, 60-, and 70-MHz bands, and disconnect the AT-1082/PRC from the radio receiver. Communicate with the distant radio stationand arrange for it to transmit using 45, 55, 65, and 75 MHz, in turn, while makingthe tasts given in sequence numbers 17 through 20 below which are associated witheach frequency.

Set BANDSWITCH to 40 and FINE TUNE to 5,Tune receiver to 45 MHz.Repeat procedures given in sequence lumbers 14 through 16

above.Set BANDSWITCH to 50 and FINE TUNE to 5.Tune receiver to 55 MH Z .Repeat procedures given in sequence numbers 14 through 16

above.Set BANDSWITCH to 60 and FINE TUNE to 5.Tune receiver to 65 MHz.

References

Fig. 2-3 , para2-7d.

Repeat procedures given in sequence numbers 14 through 16above.

Set BANDSWITCH to 70 and FINE TUNE to 5.Tune receiver to 7.5 MHz.Repeat procedures given in sequence numbcrs 14 through 16

above.

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3-5. We ekly Preventive Maintenance Checks this chart lists the illustrations, paragraphs, or

and Services Chart manuals that contain detailed repair or replace-

The preventive m aintenance checks and servicesment instructions to be followed while performing

of Antenna AT-1082/ PRC that are listed belowthe procedure.

are r eq uir ed w eek ly. Th e References column of

SequenceN o.

1


Completeness

Procedure

Inspect for completeness of a. Publications (check to S ee that they are complete, serviceable,

an d current).b. Components . . . . . . . . . . . . . .

Clean the AT-1082/PRC, extended sense whip antenna, cables,and CW-445/PRC.

Inspect cables for cuts, broken insulation and looseness of con-nectors on cable.

Check for connection to CG-3344/PRC . . . . . . .

3-6. C leaningInspect the exterior surfaces of Antenna, Loop

AT-784/ PRC, includ ing the exterior of its sensewhip antenna. All exterior surfaces should beclean an d free of dirt, grease, and fun gus.

a. Remove dust and loose dirt with a clean, softcloth.

Warning: Prolonged breathing of cleaningcompound is dangerous; make certain that ade-quate ventilation is provided. Cleaning com-pound is flammable; do not use near a flame.

References

a. DA Pam 310-4.

b. Fig. 1-1 ,app. B.

Para 3-6.

Fig. 1-1

Avoid contact with the skin; wash off any thatspills on your hands.

b. Remove grease, fungus, rust, and ground-indirt from the surfaces using a cloth dampened(not wet) with cleaning compound (FSN 7930-395-9542).

c. Remove dust or dirt from the connector witha brush.

d. Clean the control knobs: use a soft, cleancloth. If dirt is difficult to remove, dampen thecloth with water; mild soap may be used for moreeffective cleaning.

Section Il. ORGANIZATIONAL MAINTENANCE

3-7. Sc ope of Organizational MaintenanceThis section contains instructions covering orga-

nizational maintenance of Antenna AT-1082/ PRC. The duties of an organizational repairmanare limited to the responsibilities listed below inaddition to those performed by the operator (para3-2 through 3-6).

a. Monthly preventive maintenance (para 3- 8).b. Monthly preventive maintenance checks and

services (para 3- 9).c. Touchup painting (para 3-1 0).d. Replacement of parts (para 3-1 1).

3-8. M onthly Preventive Maintenance

Perform the maintenance functions indicated in

the monthly preventive maintenance checks andservices chart (para 3- 9) once each month. Amonth is defined as approximately 30 calendardays of 8-hour-per-day operation. If the equip-ment is operated 16 hours a day, the monthlypreventive maintenance checks and services shouldbe performed at 15-day intervals. Adjustments of the maintenance interval must be made to compen-s a t e f o r a n y unusual operat ing conditions.

Equipment maintained in a standby (ready forimmediate op erat ion ) con dition m u s t h a v emonthly preventive maintenance checks and serv-ices performed on it. Equipment in limited stor-age (requires service before operation) does notrequire monthly preventive maintenance.

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3-9. Mo nthly Preventive Maintenance Checks and Services Chart

1

2

345


AT-1082/PRC, ex-terior surfaces.

Cover assemblygasket.

Screws - - - - - - - - - - - - - - - -Sense whip antenna - - - -CW-445/PRC . . . . . . .

Procedure References

Repaint if necessary - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - P a r a 3 - 1 0 .

a. Pu t sm all am ount of silicone grea se on its su rface - - - - - - - - - - - a . Fig. 2-3 ,para 3-11

b. Replace lf necessary - - - - - - - - - - - - - - - - - - - - - - - - - - - - - b. Para 3-11 a .

Tighten screws h olding kn obs of cont rols an d cover a ssembly - - - - - - -Replace if it does not retract fully, is bent, or comes free - - - - - - - - - - Para 3-11 b.Inspect for tears, mildew, fraying, and attachment to strap - - - - - - - - Fig. 1-1.

3-10. To uchup Paintinga. When th e finish on t he case has been badly

scarred or damaged, rust and corrosion can beprevented by touching up the bared surfaces. UseNo. 000 sandpaper to clean t he sur face down t o thebare metal and to obtain a smooth finish.

Caution: Do not use steel wool. Minute par-

ticles may enter the case and cause harmfulinternal shorting or grounding of the circuit.b. When a touchup job is necesary, apply paint

with a small brush. Remove rust from the caseby cleaning corroded metal with cleaning com-pound. In severe cases, it may be necessary to usecleaning compound to soften the rust , and sand-paper to complete the preparation for painting.Paint used will be authorized and consistent withexisting regulations (TB SIG 364).

3-11. Re placement of Parts

(fig. 2- 3)For parts replacement, prepare a clean, flat work

surface for the unit. Thoroughly wipe off dirt,grease etc., particularly if found between thecover and the case. Use an airhose, if necessary.

a. Cover and/ or Cover Assem bly Gasket. Toreplace the cover and/or the cover assembly gas-ket, proceed as instructed below. (For lubrica-tion only, omit the procedures given in (2) and(3) below:)

(1) Loosen the six captive screws that holdthe cover assembly, and remove the cover

assem bly from t he case.(2) Pull the gasket from the cover.

Caution: Do not stretch the gasketby pulling it from one point to anotherduring its installation.

(3)

(4)

(5)

Lay the new gasket over its t rack on t hecover and press it into place.With the fingers, spread a thin coating of s il icone grease on the sur face o f thegasket.Place th e cover on th e case, ma king sur ethat the gasket is seated properly, andtighten the cover down with its six cap-tive screws.

b. Sense Whip Antenna. TO replace a whip an-tenna in the loop antenna assembly, proceed asfollows:

(1)

(2)

(3)

Set t he loop an tenn a (3, f ig. 4-6) , in operating posit ion.Hold the loop antenna and loosen thewhip antenna assembly nut (22) with ahexagonal wrench. Completely unscrewthe nut, and remove the telescoping whipantenna (21 ).

Apply a thin layer of silicone grease tothe threads on the assembly nut of thesense whip antenna to be mounted. P a rtially place the assembly into position onthe loop antenna. Extend the sense whipantenna from its assembly, and screwthe a ssembly nut in place by band; then,tighten the nu t wi th the hexagona lwrench.

c. Control Knobs. Use the following procedurefor replacement of the 13 BANDSWITCH, FINE

TUNE,(1)

(2)

and the ATTENUATOR control knobs.Note the position of the control knob(for example : BANDSWITCH se t to

30).Remove the screw that, holds the controlknob in position.

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(3) Lift and remove the control knob from (5) Mount th e new cont rol knob on t he sh aftthe associated shaft. so tha t it is set in th e same position as t he

(4) Clean the shaft and the case surface from knob which was removed ((1) above).which the control knob was removed. (6) Hold the control knob in position, and

tighten down its r etaining screw.

3 - 6

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Figure 4-2.

4-4.

fig. 4-4

4-3

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4-4

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Figure 4-3.4-4

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Fig

e44

45

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of resistors R1 through R9 on subassembly A3.The amount of attenuation is selected by AT-TENUATOR switch A3S1 in four steps. Eachof the first three steps provides approximately 10decibels (db) of attenuation, and the fourth stepprovides aproximately 6 db of attenuation. The() position of switch A3S1 couples a tap of L1directly to RF output connector J1. This antenna

has an output impedance of approximately 50ohms.e. As shown in C, figure 4-1, the pattern of a

simple loop passes two identical nulls and twoidentical ma ximum points, 180 apar t. The pa t-term leaves 180 uncertainty as to the direction of the t ransmit ter regardless of which technique(maximum pjoints or nulls) is used to find the di-rection. Since the transmitter may be either infront of or behind the loop, another element is usedto eliminate one direction. The sense of the bear-ing can be determined by introducing a small volt-

age derived upon ra ising the vertical sense whipan tenna . This sense whip antenna is a simplevertical whip antenna, 12 inches long, whose outputis mixed with that of the loop. The sense whipantenna current, caused by electric field activity,combines with the loop circuit current in trans-former L1. The vector addition of these currentsproduces the desired cardiod response (pattern D,fig. 4-1 ).

f. Superimposing the circular sense pattern overth e loop pat tern (since th ey occur at the sam e in-stant) provides the loop plus sense cardiod patternin D, figure 4-1. In D , figure 4-3, the vectors showthe loop aimed at the transmitting station. Thedott ed arr ow represents t he current in any direc-tion, while the arrow composed of triangles repre-sents the current flow within the loop (as shown inC, fig. 4-2 ) with the loop aimed at the station.Since both of these currents circulate in the same

direction, th ey add together an d provide a mar kedincrease in outpu t signal t o point t he way to thest at ion . In E , figure 4-3 , the vectors show the loopaimed away from the transmitting station. Thedotted arrow is the same current, while the arrowcomposed of triangles is the loop output current(as shown in D, fig. 4-2 ) with the loop away fromthe s ta t ion. Since these current components op-

pose each other, very little output is obtained, prov-ing this is not th e tru e direction t o the sta tion. Bysimilarly summ ing up the circular sense pat ternand the figure 8 loop pattern in all directions, thecar diod pat tern is obtained.

g. While the sensing definitely points the direc-tion t o th e tra nsmit ter, th e broadness of the lobemakes it difficult to spot the bearing sharplyenough. Using the null to sha rpen th e bearing andfollowing the null to the station (para 2-7 e) ares t a n da r d di re ct i on fi nd in g p r a ct ice s. I f t h eoperator loses his bearings and has difficulty in re-

locating the genera l direction of the tr ansm itter,th e sense operat ion should be repeated.h . The sensing current must be equal to, or

slightly less than, the net loop current. If thesense current is too small, a pattern consisting of one large lobe, one sm all lobe, an d t wo nulls lesstha n 180 apa rt is produced. If the sense currentis too high, it will mask the loop characteristicsand produce a pattern with an indistinct maximumand minimum.

i. For proper operation of Antenna AT-1082/ PRC, the signal outpu t (applied to the ]imiter of

a receiver) should be of such an amp] itude as toappear on the slope of the limiter curve. To ac-complish this, the step attenuator circuitry of AT-1082/PRC, which consists of a ladder-type pi-net-work of resistors, may be used as required (dabove) . Ti le amount of a t tenuat ion dependsupon the position of the ATTENUATOR switch(fig. 4-4 ).

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4-5.

4-6.

4-7.

4-8.

para 4-8

figure 4-5

para 3-4 b

paragraph 3

paragraph 4-8

TM 11-5527

T M 11 - 5 9 8 5 - 2 8 4 - 1 5

Sect ion I l . DIRECT SUPPORT T ROUBLESHOOTING A ND REPAIR

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4-8

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Item

1

2

3

4

5

Indication

No output signal suppliedto associated receiver.

No output during 30-MHzoperation.

No output during 40-MHz operation.

No output during 50-,60-, or 70-MHz opera-tion.

Rotation of FINE TUNEcontrol C1 causes noisein receiver.

Probable t rouble

a. S hort cd or open coaxial cable - - - - - - - - -

b. Defective ATTENU ATOR switch .

c. Defective attenuation pi-network cir-cuit.

Defectivc BANDSWITCH switch (A2S1).

a. Defective switch A2S1 - - - - - - - - - - -

b. Inductor A2L4 open or A2C4 shorted . . .

Defec t ive inductor and/or capaci tor onassembly A2 : L3 or C3 for 50-MHzoperation, L2 or C2 for 60-MHz opera-tion, L1 or C1 for 70-MHz operation.

Capaci tor C1 p la tes bent ( rub agains teach other), or shaft bearing is noisy.

Procedure

a . Make r e s i s t auce check o f c a b l e ; i f shorted, replace cable .

b. Clean and check continuity of switchA3S1 ; if defective, replace asseblyA3 .

Note. Assembly A3 includes switch and resis-tors (fig. 4-4 ).

c . C h e c k r e s i s t o r s R 1 t h r o u g h R 9 o nassembly A3 ; if any resistor is defec-tive, replace assembly

Clean an d ma ke continuity check of A2S1if switch is defective, replace assembly

A 2 .Note. Assembly A2 includes switch and circui t

components (fig. 4-4 ).

a . Check continuity of A2S1; if defective,replace assembly A2 .

b. Make res is tance check of A2 L4 andA2C4. If defective, replace assembly

Make resistance check of associated in-d u c t o r a n d c a p a c i t o r. I f d e f e c t i v e ,replace assembly A2 .

R e p a i r b e n t p l a t e s . I f c a p a c i t o r i sdefective, higher category repair is re-qu i r ed . (A l inemen t o f c i r cu i t i s r e -quired if C1 is replaced.)

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Figure 4-5. Antenna AT-1082/PRC (assembly A1), interior view.

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4-9. R epairsMost of the parts in Antenna AT-1082/PRC can

be reached easily without special procedures. Therepair du ties of a direct support m aint enan ce re-pairman are limited to the repair procedures listedbelow.

a. Removal and replacement of A1 chassis andcomponents (para 4-1 0) .

b. Removal and replacement of loop antennaarms (para 4-1 1).

Caution: Be careful when handling inductorsand rotor assemblies. Do not bend these parts.

4-10. Re moval and Replacement of Chassis

and Componentsa. Removal (figs. 4-5 and 4-6).

(1 )

(2)

(3)

(4)

(5)(6)

Remove the six captive cover screws hold-ing the cover to the case.Loosen the three retaining screws on thethree knobs; remove the knobs.Unsolder the wire from connector J1 tothe ATTENUATOR switch.Remove the three hex nuts holding thecontrol shafts in position.Lift t he chassis up and out of the case.For the removal of switch assembly A1S1or A2S1, capacitor C1, or connector J1,

unsolder the connections, unscrew the as-sociated shaft nut, and lift the releaseditem up from the chassis.

b. R eplacement.(1) Mount connector J1 to the case, and solder

(6)

(7)

4-10

its ground connection.Mount the switch assembly (A1S1 and/orA2S1) and capacitor C1 on the chassis,and screw on the associated shaft nut.Place the chassis back in the case, andtighten the three hex nuts on the controlshafts of A1S1, A2S1, and C1. Then,attach the switch knobs.Install the six mounting screws for hold-ing tile chassis to th e case.

Solder the connections of the replaceditems, and solder in capacitors C2 and C3,if required.Solder the wire from ATTENUATORswitch A2S1 connector to J1.Place the cover on the case, making surethat the rubber gasket is seated properly,

and tighten t he cover down with t he sixcaptive screws.

4-11. Re placement of Loop Antenna ArmsTo replace loop antenna arms, follow the pro-

cedures outlined in a and b below. For item num-bers given in a a n d b below, refer to figure 4-6.

a. Removal. For removal of the loop antenna

left side only (antenna coaxial arm assembly, item4), omit the procedures in (5) below. All proce-dures listed are required for removal of both loopantenna sides (items 3 and 4). Item 3 (antennaarm assembly) is the loop antenna right side.

(1)

(2)

(3)

(4)

(5)

(6)

(7 )

If possible, set t he loop an tenn a into itsoperating position.Unscrew the six cover screws, and re-move the cover (1) from the case (2).On the side of the loop antenna to beremoved, antenna arm assembly (3) and/ or ant enna coaxial arm assembly (4), pull

th e E-ring (5) from it s mount ing.Uns crew th e coupling cap (6), an d slidei t to the sense whip antenna as far aspossible.For removal of ant enna coaxial arm as-sembly (4), remove the leaf springs (7an d 8) tha t ar e mount ed on th e case.Unsolder the tinned copper wire (9)from the contact plug (10). When heat-ing cont act plug (10), hold th e solderingiron there and push the top portion of th e ant enna arm assembly (3 or 4) to be

removed while having an assistant repair-man press the contact point of that assem-bly from the case (2).

Caution: Once the tinned copperwire (9) has been removed from thecontact plug (10), remove the solder-ing iron. This will prevent damage toeither antenna arm assembly side (3or 4) of the loop antenna.

After the desired antenna arm assembly(3 or 4) has been dismounted, remove

O-rings (11) and spring washer (12) asrequired. If ant enna coaxial arm a ssem-bly (4) has been dismounted, remove thenut from the contact plug (10), lock-washer (13), cent act plug (10), capbearing (14), and coupling cap (6), asrequired.

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b. Replacement. For replacement of the an-tenna arm assembly (3) only, omit the proceduresgiven in a(1), (4), and (8) below. All proceduresare required for the replacement of a completeloop antenna.

(1)

(2)

(3)

(4)

For antenna coaxial arm assembly (4)replacement, apply glyptal compound (orequivalent ) to the threads of the contact

plug (10), screw the contact plug (10)in place on ant enna coaxial arm assembly(4), slide on the coupling cap (6), insertthe cap bearing (14) over the contact plug(10) into the coupling cap (6), place thelockwasher (13) on the contact plug (10),and screw on the nut for the contact plug(10).For antenna arm assembly (3 or 4) re-

placement, apply a layer of silicone greaseto the arm assembly surface which willmeet t he spring washer (12). Mount the

spring washer (12) with the O-rings (11).Set the case (2), with its cover (1) re-moved, in place for loop an ten na mount -ing. (If either antenna arm assembly(3 or 4) has not been removed, raise thatassembly to i t s opera t ing pos it ion . )Cover the replaced O-rings (11) with athin layer of silicone grease, and set theant enna arm assembly (3 or 4) in its oper-ating position for mounting.Insert the antenna arm assembly of one

(5)

(6)

(7)

(8)

(9)

TM 11-5985-284-15

loop antenna side (3 or 4) into its mount-ing hole on proper side of the case (2).Insert t he base of that arm assembly (3or 4) slightly into its associated mountinghole on t he case (2), and check t he a line-ment of the contact plug (10) with thetinned copper wire (9) which is containedin ant enna arm assembly (3).

With the tinned copper wire (9) and thecent act plug (10) in alinement, press theantenna arm assembly (3 or 4) that isbeing mounted, into the case (2).Solder the tinned copper wire (9) andthe contact plug (10). Slide the cou-pling cap (6) into position, and screw itto the other antenna arm assembly (4).For the antenna coaxial arm assembly(4), inser t E-ring (5) in pla ce on th e bot-tom of its antenna arm assembly. Placeleaf springs (8) and (7) in position, and

secure them to the case (2).For the antenna arm assembly (3), insertE-ring (5) in place on the bottom of itsant enna arm a ssembly.

(10) Turn the case (2) over, and check to besure t hat the loop ant enna can be lockedin its detented position and easily placedin its operating position.

(11) Place the cover (1) on the case (2),making sure that the rubber gasket isseated properly, and tighten the coverdown with the six captive screws.

(1

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F i g ur e

4 - 6 .A

n t e n n aA T -1

0 8 2

/ P R

C ( a

s s e m b l y

A 1 ) , l o c a t i o n o f r e m

o v a b l e p ar t s .

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para 5-2 para 5-7para 5-7

TM 11-5985-284-15

CHAPTER 5

GENERAL SUPPORT MAINTENANCE

Sect ion I . REPAIR AND ALINEMENT

5-1. R epai r

a. Maintenance of Antenna. AT-1082/PRC atgeneral support level consists of replacing com-ponents on assemblies A2 and A3, performing thefrequency range alinem ent (pa ra 5-2), and per-forming the general support testing procedures(paras 5-3 through 5-8).

b. BANDSWITCH assembly A2 and ATTEN-UATOR switch assem bly A3 each contain ing itsswitch an d component s (figs. 4- 4 an d 4-5), can bereplaced or the assembly components can be re-placed. Refer t o para graph 4-10 for r emoval andreplacement procedures for the switch assemblies.To replace defective components on either switchasem bly, unsolder th e defective component s an d

5-2. Fr equency Range Al inemen t P rocedures

a. General. The frequency range alinementprocedur es given in b below ar e perform ed whencomponents of BANDSWITCH assembly(figs. 4-4 and 4-5) are replaced and when theperformance standard given in the frequencyrange tes ts (para 5-7 ) is not within limits. The30- and 39-MHz test frequencies are used as thetest frequencies; other frequencies used in the op-era tion of th e AT-1082/PRC sh ould pa ss t hr oughsatisfactorily.

b. Procedure.

(1) Perform the operations given in stepNo. 1, paragraph 5-7.

(2) When th e procedur es given in step No. 1,paragraph 5- 7 are completed, set the AT-1082/PRC controls as follows:

(a) ATTENUATOR: 0.(b) F I N E T U N E : 0 .(c) BANDSWITCH :30.

install their replacements..(1) After an inductor or capacitor on BAND-

SWITCH assembly A2 has been replaced,perform the alinement procedures givenin paragraph 5- 2 and th en th e perform-an ce procedure given in t he char t belowassociated with the replaced component.

A2 C o m p o n e n t Perform ance proced ure

Adjust the slug in coil L1 (fig. 4- 5) toobtain a reading of 30 MHz on frequencyMeter AN/URM-80.Readjust Signal Generator AN/USM-44 for an output frequency of 39 MHz.Set FINE TUNE control C1 on the AT-1082/PRC t o 9.Adjust capacitor C3 to obtain a readingof 39 MHz on the AN/URM-80.Repeat the procedures in (3) above: re-adjust L1 if necessary.Repeat the procedures in (4), (5), and(6) above; readjust C3 if necessary.Turn off the power, and disconnect the

(3)

(4)

(5)

(6)

(7)

(8)

(9)

L1 , C1 (70 MHz)_ Para 5-7 , step No. 5.L2 , C2 (60 MHz) - Para 5-7 , step No. 4.L3 , C3 (50 MHz) - Para 5-7 , step No. 3.L4 , C4 (40 MHz)- Para 5-7 , step No. 2.

Afte r a res i s to r on ATTENUATOR(2 )switch assembly has been replaced,perform the testing procedures given inst ep 2, o f paragraph 5-8 c through h.

c. When capacitor C1 (FINE TUNE control),

C2, or C3 (figs. 4-4 and 4-5) is replaced, perform equipment . (See p a r a 5 -1a(1); otherthe alinement procedures given in para graph 5-2.

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Section Il. GENERAL SUPPORT TESTING PROCEDURES

5-3. G enera l pod, 50 inches in h eight, with a nonmet allic disk a. Testing procedures a re pr epared for u se by

Electronics Field Maintenance Shops and Elec-tronic Service Organizations responsible for gen-eral support maintenance of electronics equipmentto determine the acceptability of repaired elec-

tronics equipment. These procedures set forthspecific requirements that repaired electronicsequipment must meet before it is ret urn ed to theusing organizat ion. The testing pr ocedures mayalso be used as a guide for the testing of equip-ment that has been repaired at direct support leveli f the p roper too l s and tes t equ ipment a reavailable.

b. Comply with the instructions preceding eachchart before proceeding to the chart. Performeach test in sequence. Do not vary the sequence.

For each step, perform all th e actions r equiredin the Test equipm ent control setting a n d Equip-m ent un der test control settings columns; then per-form each specific test procedure and verify itagainst its performance standard.

5-4. Te s t Equipment Requi redAll test equipment required to perform the test-

ing procedures given in this section are listed inthe following chart and are authorized underTA 11-17, and TA 11-100(11-17).

a. Test Equ ipment.

Nomenclature

Signal Generator A N / U S M -44 .

Mult imet er, ME -26A/U - - - - - -

Frequency Meter AN/ URM-80.

Resistor, carbon 47-ohm,1/2-watt.

Radio Interference Measur-ing Set, AN/URM-85.

Fede ra l s t ock

6625-669-0241

6625-360-2493

6625-649-4286

- - - -- - - -

6625-776-0595

Techn i ca l manua l

TM 11-6625-508-10.

TM 11-6625-200-12.

TM 11-5095.

- - - - - - - - - - -

TM 11-6625-351-12.

b. Other Equipm ent Required. To conduct thefrequency range test, construct a nonmetallic tri-

sitting on top. This disk should be calibrated in1 markings from 0 to 360 and be attached toa wooden handle (minimum of 36 inches long)which will be used to rotate the disk. The testantenna should then be mounted on top of the disk

with provisions made for cable entry and a degreepointer. The pointer should be alined so thatwhen t he disk is rotat ed, the point er will line upwith the degree markings on the disk.

5-5. Te s t C o n d i t i o n s(fig. 5-1)

a. All test s sh all be condu cted in a n open fieldwhich is free from all reflective objects.

b. Place Signal Generator AN/USM-44 on theground with a 34-inch vertical antenna connecteddirectly to the coaxial RF OUTPUT connector

and terminated into a 47-ohm carbon resistor.c. The signal genera tor should be placed on itsback to enable the entire length of the antenna toextend (34 inches ) above the signal generator topsurface.

d . Set the output-of the signal generator to 0.5volt with no modulation at each test frequency.

e. Place Frequency Meter AN/URM-80 on ata ble in a position a s close as possible to the t estan tenna .

f. Place Antenna AT-1082/PRC on a tripod50 inches high a nd cent ered over a 25-foot point

of an imaginary line drawn between the signalgenerator a nd t he AT-1082/PRC un der test ,

g. Connect the CG-3344/PRC 5-foot coaxialcable between the AT-1082/PRC and the fre-quency meter.

h . A power source of 110 to 120 volts, alternat-ing current ( ac), 60 Hertz (Hz) is required to pro-vide operating voltages for test equipment listedin paragraph 5-4.

5-6. Ph ys ica l Tes t s and Inspec t iona. Test Equipment and Material. None.b. Test Connections and Conditions. Remove

cover from case.

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c. Procedure.

1

2

Testequipment

settings

N/A___

N/A___

Equipment undertest control

settings

Controls maybe in anyposition.

Controls maybe in anyposition.

Test procedure

a . I n s p e c t a l l c o n t r o l s a n d m e c h a n i c a lassemblies for loose or missing screws.

b. Inspect coaxial connector for loosenessor damage.

a . R o t a t e B A N D S W I T C H , AT T E N U -ATOR, and FINE TUNE controls.

Note. FINE TUNE control will rotate through360.

b. Check to see that loop antenna extendsand folds down and that detent mech-anism locks antenna loop in place.

TM 11-5985-284-15

Performance standard

a. Screws, bol ts , and nuts wi l l be t ight ;none missing.

b. No looseness or damage evident.

a . Con t ro l s w i l l r o t a t e f r e e l y w i t h o u tbinding or excessive looseness.

b. Loop antenna moves freely, withoutexcessive bin ding.

5 - 3

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Fig

e51

5 - 4

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Fig

e52

56

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5

f

p

T M 1 1 - 5

9 8 5 - 2

8 4 - 1

5

C h ange4

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C h an

g e

5

5 - 1

5

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6

C h

an

g e 5

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C h an

g e 5

5 - 1 7

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8

C h

an

g e

5

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C h

an

g e 5

5 - 1

9 / ( 5 - 2

0

b l ank

)

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CHAPTER 6

DEPOT OVERHAUL STANDARDS

6-1. Sc opeThe depot overhaul standards for Antenna,

Loop AT-784/PRC, are designed to measure theperformance capability of repaired equipment.Equipment that meets the minimum standardsstated in the tests will furnish satisfactory opera-tion, equivalent to that of new equipment.

6-2.To

Depot Overhaulperform the tests

Standardsfor the depot overhaul

standards of Antenna, Loop AT784/PRC, useprocedures for the general support testing pro-cedures given in paragraphs 53 through 5-8.The tools and test equipment required for the pro-cedures are given in paragraph 5-4 . If the FINETUNE control is consistently beyond position 2during the frequency range tests (para 5- 7)adjust coil L1 and capacitor C3 using the pro-cedures in paragraph 5-2. After the adjustment,repeat the frequency range tests ( para 5-7 ).

6-

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CHAPTER 7

SHIPMENT AND LIMITED STORAGE AND DEMOLITION TOPREVENT ENEMY USE

Section I. SHIPMENT AND LIMITED STORAGE

7-1. Di sassembly 7-2. Re packing for Shipment or LimitedStorage

If Antenna AT-1082/PRC is connected to a To repack for quick shipment or limited stor-radio set, disconnect and remove its cable, retract age, place the AT1082/PRC and its connectingthe sense whip antenna, and turn down the loop. cables into Bag, Cotton Duck CW-445/PRC.

Section Il. DEMOLITION OF MATERIEL TO PREVENT ENEMY USE

7-3. Au thority for DemolitionDemolition of the equipment will be accom-

plished only upon the order of the commander.The destruction procedures outlined in paragraph7-4 will be used to prevent further use of theequipment.

7-4. Met hods of DestructionUse any of the following methods to destroy the

equipment.a. Smash. Smash the antenna (loop and sense

whip), switches, and case; use sledges, axes, hand-axes, hammers, or crowbars.

b. Cut. Cut the output cables; use axes, hand-axes, knives, or machetes.

Warning: Be extremely careful with explo-sives and incendiary devices. Use these itemsonly when the need is urgent.

c. Burn. Burn cords, cables, and technicalmanuals; use gasoline, kerosene, oil, flame throw-ers, or incendiary grenades.

d. Explode. If explosives are necessary, usefirearms, grenades, or TNT.

e. Dispose. Bury or scatter the destroyed partsin slit trenches or foxholes, or throw them intostreams.

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TM 115985-284-1

APPENDIX AREFERENCES

DA Pam 310-4

DA Pam 310-7TB 43-0118

TM 11-5095TM 11-5820-398-12

TM 11-5985-284-24P

TM 11-6625-200-15

TM 11-6625-351-12

TM 11-6625-366-15

TM 11-6625-508-10

TM 38-750TM 750-244-2

Index ofTechnical Manuals, Technical Bulletins, Supply Manuals(Types 7, 8, and 9), Supply Bulletins and Lubrication Orders.

US Army Index of Modification Work Orders.Field Instructions for Painting and Preserving Electronic Com-

mand Equipment Including Camouflage Pattern Painting ofElectrical Equipment Shelters.

Frequency Meter AN/URM-80.Operator and Organizational Maintenance Manual Including Re-

pair Parts and Special Tool Lists: Radio Set AN/PRC-25 (Includ-ing Receiver-Transmitter, Radio RT505/PRC25).

Organizational, Direct Support, and General Support Mainte-nance Repair Parts and Special Tools Lists (Including DepotMaintenance Repair Parts and Special Tools): Antenna, LoopAT-784/PRC.

Operators, Organizational, DS, GS, and Depot Maintenance Man-ual: Multimeters ME-26A/U, ME26B/U, ME-26C/U, and ME 26D/U.

Operator and Organizational Maintenance Manual: Radio Inter-ference Measuring Set AN/URM-85.

Operators, Organizational, DS, GS, and Depot Maintenance Man-ual: Multimeter TS352B/U.

Operators Manual: Signal Generators AN/USM44 and AN/ USM44A.

The Army Maintenance Management Systems (TAMMS).Procedures for Destruction of Electronics Materiel to Prevent

Enemy Use (Electronics Command).

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C 2, TM 11-5985-284-15

APPENDIX B

BASIC ISSUE ITEMS LIST

Section I. INTRODUCTION

B- 1. ScopeThis appendix lists only basic issue items re-quired by the crew/operator for installation,operation, and maintenance of Antenna,Loop AT-784/PRC.

B-2. GeneralThe basic issue items list (Section II is a list,

in alphabetical sequence, of items which arefurnished with, and which must be turned inwith the end item.

B-3. Explanation of ColumnsThe following provides an explanation of col-umns found in the tabular listings:

a. Illustration. This column is divided asfollows:

(1) Figure Number. Indicates the figurenumber of the illustration in which the itemis shown.

(2) Item Number. Not applicable.b. Federal Stock Number. Indicates theFederal stock number assigned to the itemand will be used for requisitioning purposes.

c. Part Number. Indicates the primarynumber used by the manufacturer (indi-

vidual, company, firm, corporation, or Gov-ernment activity), which controls the designand characteristics of the item by means of itsengineering drawings, specifications stand-ards, and inspection requirements, to identifyan item or range of items.

d. Federal Supply Code for Manufacturer (FSCM). The FSCM is a 5-digit numeric codeused to identify the manufacturer, dis-tributor, or Government agency, etc., and isidentified in SB 708-42.

e. Description. Indicates the Federal itemname and a minimum description required toidentify the item.

f. Unit of Measure (U/M). Indicates thestandard of basic quantity of the listed itemas used in performing the actual mainte-nance function. This measure is expressed bya two-character alphabetical abbreviation,(e.g., ea, in., pr, etc.). When the unit of meas-ure differs from the unit of issue, the lowest

unit of issue that will satisfy the requiredunits of measure will be requisitioned.g. Quantity Furnished with Equipment

(Basic Issue Items Only). Indicates the quan-tity of the basic issue item furnished with theequipment.

Section Il. BASIC ISSUE ITEMS LIST

(1) (2) (3) (4)I l lus t ra t ion

(5) (6) (7)

Federal(A) (B) Stock Part

Uni tDescription

QT Y

I T E M Number Number FSCMo f

NO.Usable Mess

on Code EQUIP

1 - 1 5 9 8 5 - 9 7 3 - 0 7 7 3 S C - D L - 5 0 8 8 1 9 8 0 0 6 3 B A G , C A N V A S C W - 4 4 5 / P R C E A 1

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APPENDIX CMAINTENANCE ALLOCATION

Section I. INTRODUCTIONC-1. GeneralThis appendix provides a summary of themaintenance operations for AT784/PRC. Itauthorizes categories of maintenance forspecific maintenance functions on repairableitems and components and the tools andequipment required to perform each function.This appendix may be used as an aid in plan-ning maintenance operations.

C2. Maintenance FunctionMaintenance functions will be limited to anddefined as follows:

a. Inspect. To determine the serviceabilityof an item by comparing its physical, mechan-ical, and/or electrical characteristics with es-tablished standards through examination.

b. Test. To verify serviceability and to de-tect incipient failure by measuring themechanical or electrical characteristics of anitem and comparing those characteristicswith prescribed standards.

c. Service. Operations required periodicallyto keep an item in proper operating condition,i.e., to clean (decontaminate), to preserve, todrain, to paint, or to replenish fuel, lubri-cants, hydraulic fluids, or compressed airsupplies.

d. Adjust. To maintain, within prescribedlimits, by bringing into proper or exact posi-tion, or by setting the operating characteris-tics to the specified parameters.

e. Align. To adjust specified elements of anitem to bring about optimum or desired per-formance.

f. Calibrate. To determine and cause cor-rections to be made or to be adjusted on in-struments or test measuring and diagnosticequipment used in precision measurement.Consists of comparisons of two instruments,one of which is a certified standard of knownaccuracy, to detect and adjust any discrep-

ancy in the accuracy of the instrument beingcompared.

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 serv-iceable like type part, subassembly, ormodule (component or assembly) for an un-

serviceable counterpart.i. Repair. The application of maintenanceservices (inspect, test, service, adjust, align,calibrate, replace) or other maintenance ac-tions (welding, grinding, riveting, straighten-ing, facing, remachining, or resurfacing) torestore serviceability to an item by correctingspecific damage, fault, malfunction, or failurein a part, subassembly, module (component orassembly), end item, or system.

j. Overhaul. That maintenance effort(service/action) necessary to restore an itemto a completely serviceable/operational condi-tion as prescribed by maintenance standards(i.e., DMWR) in appropriate technical publica-tions. Overhaul is normally the highest de-gree of maintenance performed by the Army.Overhaul does not normally return an item tolike new condition.

k. Rebuild. Consists of those services/ actions necessary for the restoration of un-serviceable equipment to a like new conditionin accordance with original manufacturingstandards. Rebuild is the highest degree ofmateriel maintenance applied to Army

equipment. The rebuild operation includesthe act of returning to zero those age meas-urements (hours, miles, etc. ) considered inclassifying Army equipments/components.

C3. Column Entriesa. Column 1, Group Number. Column 1 lists

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group numbers, the purpose of which is toidentify components, assemblies, subas-semblies, and modules with the next higherassembly.

b. Column 2, Component/Assembly. Column2 contains the noun names of components,assemblies, subassemblies, and modules forwhich maintenance is authorized.

c. Column 3, Maintenance Functions. Col-umn 3 lists the functions to be performed onthe item listed in column 2. When items arelisted without maintenance functions, it issolely for purpose of having the group num-bers in the MAC and RPSTL coincide.

d. Column 4, Maintenance Category. Col- umn 4 specifies, by the listing of a worktime figure in the appropriate subcolumn(s),the lowest level of maintenance authorized toperform the function listed in column 3. Thisfigure represents the active time required toperform that maintenance function at the in-dicated category of maintenance. If thenumber or complexity of the tasks within thelisted maintenance function vary at differentmaintenance categories, appropriate worktime figures will be shown for each category.The number of task-hours specified by thework time figure represents the averagetime required to restore an item (assembly,subassembly, component, module, end item orsystem) to a serviceable condition under typi-cal field operating conditions. This time in-cludes preparation time, troubleshootingtime, and quality assurance/quality controltime in addition to the time required to per-form the specific tasks identified for themaintenance functions authorized in themaintenance allocation chart. Subcolumns ofcolumn 4 are as follows:

C-Operator/CrewO-OrganizationalFDirect SupportHGeneral SupportD-Depot

e. Column 5, Tools and Equipment. Column5 specifies by code, those common tool sets(not individual tools) and special tools, test,and support equipment required to performthe designated function.

f. Column 6, Remarks. Column 6 containsan alphabetic code which leads to the remarkin section IV, Remarks, which is pertinent to

the item opposite the particular code.

C-4. Tool and Test Equipment Requirements(Sect. Ill)

a. Tool or Test Equipment Reference Code.The numbers in this column coincide with thenumbers used in the tools and equipment col-umn of the MAC. The numbers indicate theapplicable tool or test equipment for themaintenance functions.

b. Maintenance Category. The codes in thiscolulmn indicate the maintenance category al-located the tool or test equipment.

c. Nomenclature. This column lists thenoun name and nomenclature of the tooIs andtest equipment required to perform themaintenance functions.

d. Natioal/NATO Stock Number. This col-umn lists the National /NATO stock numberof the specific tool or test equipment.

e. Tool Number. This column lists the man-ufacturers part number of the tool followed

by the Federal Supply Code for manufactur-ers (5-digit) in parentheses.

C-5. Remarks (Sect. IV)

a. Reference Code. This code refers to theappropriate item in section II, column 6.

b. Remarks. This column provides the re-quired explanatory information necessary toclarify items appearing in section II.

(Next printed page is C-3)

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