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TM 11-5821-204-12D 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’S AND ORGANIZATIONALMAINTENANCE MANUAL

RADIO SET AN/ARC-44

HEADQUARTERS, DEPARTMENT OF THE ARMY30 NOVEMBER 1960

WARNING

DANGEROUS VOLTAGES EXIST IN THIS EQUIPMENT

DON’T TAKE CHANCES!

DANGEROUS VOLTAGES EXIST IN THE FOLLOWING UNITS:

RECEIVER-TRANSMITTER, RADIO RT–294(*)/ARC-44 300-volt circuits,DYNAMOTOR DY–107(* ) /AR 300-volt circuits.

Do not make contact with exposed wires or connectors. Be safe.Turn all power supplies OFF before making any connections ordisconnections.

Change in force:C2, C3, C4, and C5

TM 11-5821-204-12C 5

CHANGE

No. 5} HEADQUARTERS

DEPARTMENT OF THE ARMYW ASHINGTON , D. C., 10 .May 1.974

Operator’s and Organizational Maintenance ManualRADIO SET AN/ARC-44

TM 11-5821-204-12, 30 November 1960, is changed as follows:

Page 5. Delete paragraphs 2, 2.1, and 2.2 andsubstitute:

2. Indexes of Publications

a. DA Pam 310-4. Refer to the latest issue of DAPam 3104 to determine whether there are neweditions, changes, or additional publications per-taining to the equipment.

b. DA Pam 310-7. Refer to DA Pam 310-7 todetermine whether there are modification workorders (MWO’s) pertaining to the equipment.

2.1. Forms and Records

a. Reports of Maintenance and UnsatisfactoryEquipment. 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 Deficien-ties. Fill out and forward DD Form 6 (Report ofPackaging and Handling Deficiencies) as pre-scribed in AR 700-58/NAVSUP PUB 378/AFR71-4/MC0 P4030.29, and DSAR 4145.8.

c. Discrepancy in Shipment Report (DISREP )(SF 361). Fill out and forward Discrepancy inShipment Report (DISREP) (SF 361) as prescribedin AR 55-38/NAVSUPINST 4610.33/AFM75-18/MCO P461O.19A, and DSAR 4500.15.

2.2. Reporting of Equipment PublicationImprovements

The Reporting of errors, omissions, and recom-mendations for improving this publication by theindividual user is encouraged. Reports should besubmitted on DA Form 2028 (RecommendedChanges to Publications and Blank Forms), andforwarded direct to Commander, US Army Elec-tronics Command, ATTN: AMSEL-MA-C FortMonmouth, NJ 07703.

2.3 Handling, Storage, and Disposal ofRadioactive Material

Follow the procedures for safe handling, storage,and disposal of radioactive material as directed byTB 750-249.

Page 8. Delete paragraph 5 and substitute:

1

5. Items Comprising an Operable Equipment

Page 51. Delete appendix III.

2

PIN : 022912-005

Changes in force: C2, C3, and C4

Change

No. 4}

TM 11-5821-204.12C 4

HEADQUARTERSDEPARTMENT OF THE ARMYWashington, D. C., 26 May 1971

Operator’s and Organizational Maintenance ManualRADIO SET AN/ARC-44

TM 11-5821-204-12,30 November 1960, is changed as follows:

Change “DA Pam 310-4” to “DA Pam 310-7” in thefollowing places: WORK ORDERS, Item column and References

Page 25, paragraph 30.4. Item No. 3 MODIFI- column.

CATION WORK ORDERS. Item column and Add the following Warning Notice to the insideReferences column. Item No. 14 MODIFICATION of the front cover.

RADIATION HAZARD

Co 60

1

Tube types 5829/WA and 5787/WA used in this radio set contain radioactivematerial (See TB 750-249). The tubes present no radiation hazard to personnelunless broken. See qualified medical personnel and contact the RadiologicalProtection Officer if you are exposed to or cut by broken tubes. Follow the firstaid instructions contained in TB 750-249. Use extreme care in replacing thesetubes and follow safe procedures in their handling, storage, and disposal (SeeTB 750-249). A beta-gamma radiac meter AN/PDR-27 (*) or equivalent may beused to measure radiation levels.

Never place radioactive tubes in your pocket.Use extreme care not to break radioactive tubes while handling them.Never remove radioactive tubes from cartons until ready to use them.

Page 5. Delete paragraph 2 and substitute.

2. Forms and Recordsa. Reports of Maintenance and Unsatisfactory

Equipment. Use equipment forms and records inaccordance with instructions in TM 38-750.

b. Report of Packaging and Handling Deficien-ties. Fill out and forward DD Form 6 (Report ofPackaging and Handling Deficiencies) as pre-scribed 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 (DISREP)(SF 361). Fill out and forward Discrepancy inShipment Report (DISREP) (SF 361) as prescribedin AR 55-38 (Army), NAVSUP Pub 459 (Navy),AFM 75-34 (Air Force), and MCO P4610.19(Marine Corps).

d. Report of Equipment Publication Improve-ments. The reporting of errors, omissions, andrecommendations for improving this publicationby the individual user is encouraged. Reportsshould be submitted on DA Form 2028 (Recom-mended Changes to Publications) and forwardeddirect to Commanding General, U.S. Army Elec-tronics Command, ATTN: AMSEL-ME-NMP-EM,Fort Monmouth, N. J. 07703.

Delete paragraph 2.1 and substitute.

2.1 Indexes of Equipment Publicationsa. DA Pam 310-4. Refer to the latest issue of

DA Pam 310-4 to determine whether there are neweditions, changes, or additional publications per-taining to the equipment.

b. DA Pam 310-7. Refer to DA Pam 310-7 todetermine whether there are modification workorders (MWO’s) pertaining to the equipment.

Add paragraph 2.2 after paragraph 2-1.

2.2 Handling, Storage, and Disposal ofRadioactive MaterialFollow the procedures for safe handling, storage,and disposal of radioactive material as directedby TB 750-249.

Page 37. Appendix. Change “TM 38-750 TheArmy Equipment Record Systems and Procedures”to “TM 38-750 The Army Maintenance Manage-ment System (TAMMS). "

Add the following to the appendix.TB 750-249 Instructions for Safe Handling and

Identification of U.S. ArmyElectronics Command ManagedRadioactive Items in the ArmySupply System.

2

TM 11-5821-204-12C 3

TECHNICAL MANUAL

OPERATOR’S AND ORGANIZATIONAL MAINTENANCE MANUALRADIO SET AN/ARC-44

TM 11-5821-204-12 HEADQUARTERS,DEPARTMENT OF THE ARMY

C H A N G E S No. 3 Washington 25, D. C., 15 Febuary 1963

TM 11-5821–204-12, 30 November 1960, is changed as follows:

Note. The parenthetical reference to previous Changes(example: “page 5 of C 2“ ) indicate that pertinent materialwas published in that Changes.

Change ‘(DD Form 781-2” to: “DA Form 2408-13” in the following places:

Page 23, paragraph 24b, last line.Page 25, paragraph 27, lines 6 and 7. Para-

graph 31a, line 12.Page 26’, paragraph 3 la, line 6.

Page 5. Delete paragraph 2 and substitute.

2. Forms and Recordsa. Reports of Maintenance and Unsatisfactory

Equipment. 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 ofDamaged or Improper Shipment) as prescribed inAR 700-58 (Army), NAVSANDA Publication 378(Navy), and AFR 714 (Air Force).

c. Comments on Manual. Forward all commentson this publication direct to: Commanding Officer,U.S. Army Electronics Materiel Support Agency,ATTN: SELMS-MP, Fort Monmouth, N.J. (DAForm 1598 (Record of Comments on Publications),DA Form 2496 (Disposition Form), or letter maybe used.)

Add paragraph 2.1 after paragraph 2.

2.1 Index of PublicationsRefer to the latest issue of DA Pam 310-4 to

determine whether there are new editions, changesor additional publications pertaining to your equip-ment. Department of the Army Pamphlet No.310–4 is a current index of technical manuals,technical bulletins, supply bulletins, lubricationorders, and modification work orders that are avail-able through publications supply channels. Theindex lists the individual parts (-10, -20, -35P, etc. )and the latest changes and revisions of each equip-ment publication.

TAGO 7998-A-February

Page 6, figure 2. Make the following changes:Below “H-101 (*)/U,” add: (NOTE 3).Add the following to the notes:3. H-101 (*)/U IS CONNECTED THROUGH

THE AIRCRAFT JUNCTION BOX TOTHE SB-329/AR.

Page 25, paragraph 28. Make the followingchanges:

Subparagraph b. Delete subparagraph b andsubstitute.

b. Tool Kit TK-115/U.Add subparagraph d after subparagraph c.

d. Tool Kit TK-105/G.Delete paragraph 30 and substitute.

30. Preventive Maintenance

a. Preventive rnaintenance is the systematiccare, inspection, and servicing of equipment tomaintain it in a serviceable condition, preventbreakdowns, and assure maximum operationalcapability. Preventive maintenance is the re-sponsibility of all echelons concerned with the equip-ment and includes the inspection, testing, andrepair or replacement of parts, subassemblies, orunits that inspection and tests indicate wouldprobably fail before the next scheduled periodicservice. Preventive maintenance service and in-spection of Radio Set AN/ARC–44 at the secondechelon level are made at daily (ch. 3), intermediate(par. 30. 1), and periodic (par. 30.4) intervals unlessotherwise directed by the commanding officer.The maintenance services should be scheduledconcurrently with the periodic service schedule ofthe aircraft for all aircraft installations.

b. Maintenance forms anti records to be used andmaintained on this equipment are specified in TM38–750. Paragraph 2 contains additional infor-mation concerning submission of specified forms.

Add paragraphs 30.1 through 30.4 after paragraph30.

1

30.1 Intermediate Maintenance condition must have intermediate maintenance

Perform the maintenance functions indicated inperformed on it. Equipment in limited storage(requires service before operation) does not require

the intermediate maintenance and inspection chart intermediate maintenance. The item numbers in(par, 30.2) at the time intermediate inspections are the chart are not consecutive; they are taken fromscheduled for the aircraft. Equipment maintained the complete periodic maintenance service andin a standby (ready for immediate operation) inspection chart (par. 30.4).

30.2 Intermediate Maintenance Service and Inspection ChartNote. Omit items 12, 15, 16, and 18 if the AN/ARC-44 does not have the auxiliary equiprnents AN/ARA-31 and SA-474/AR.

No.Item

4

5

7

9

11

12

15

16

18

- - - - - - - -- - - - - - - - - -- - - -- - - -- - - - - -- - - - - - - - - - -- - - - -- - - - - Item

FUSES: Check for proper fuses (F101 andFI02) in Dynamotor DY-107(*)/AR.

BRUSHES: Inspect Dynamotor DY-107(*)/ Par 32.AR brushes and brush caps.

CONNECTIONS: Check the connections ofall cables interconnecting the componentsof the equipment, including the headset-microphone and antenna connections.

ANTENNA: Inspect Antenna AT-454(*)/ARC.

S Q U E L C H A D J U S T M E N T : CheckSQUELCH control operation on the fmreceiver-transmitter for proper operation.

AUXILIARY EQUIPMENT: Inspect An-tenna Group AN/ARA-31 and Switch As-sembly SA–474/AR for—

a. Completeness. . . . . . . . . . . . . . . . .

b. Cleanliness- - - - - -- - - - - -

c . P re se rvn t ion . . . . . . . . . . .

MOUNTING: Inspect for seating, stability,and looSe or missing hardware of A N /ARA–31 and SA–474/AR mountings.

CONNECTIONS: Check the connections ofall cables interconnecting the componentsof Antenna Group AN/ARA–3l, SwitchAssembly SA-474/AR, and Radio Set AN/ARC-44.

ANTENNA: Inspect Antenna Element AT-624(”) /AR on the aircraft.

Normal condition or result

There should be two 1/2-ampere, MO-volt, 3AGtype fuses.

Brushes not chipped, broken, or worn to brushwear line.

Connections not loose and connectors properlyfitted into their respective receptacles andclean. Cables not frayed.

Antenna is complete with whip, base, andcoupler. Whip is securely attached to baseand tilted 15°, and base is secured to aircraftsurface. No kinks in whip.

Backgrounrl noise in headset is at a comfortablelevel.

a . E q u i p m e n t m u s t b e c o m p l e t e .

b. Units must be clean and dry inside and out:free of grease, dirt, rust, corrosion, and fungus.

c. Pointed surfaces must be free of bare spots,rust, and corrosion.

All components securely mounted in place. Nonuts, bolts, or other fasteners loose or brokenon mountings.

Connections not loose and connectors properlyfitted into their respective receptacles andclean. Cables not frayed.

The antenna elements are firmly attached to theantenna element connectors and the plasticcoating of the antenna elements is unbroken.

References

Fig. 6.

a. Fig. 2.b. Configuration

manual of appli-cable aircraft.

Par. 12.

Para. 34.

a. TM 11–5985–200- l2

a. TM 11–5985-200-12.

b. Configurationmanual of appli-cable aircraft.

Configurationmanual of appli-cable aircraft.

a. TM 1l-5985-200-12.


30.3 Periodic Maintenance maintenance inspection should be scheduled con-

Periodic maintenance of Radio Set AN/ARC-44 currently with the periodic maintenance service

will be scheduled in accordance with the require- schedule of the aircraft in which the equipment is

mcnts of TM 38–750. The equipment will normally installed to reduce out-of-service time to a minimum.bc part of an aircraft installation. The periodic All deficiencies or shortcomings will be immediately

2 TACO 7998-A

APPENDIX Ill (Superseded)

BASIC ISSUE ITEMS FOR RADIO SET AN/ARC-44

Section 1. INTRODUCTION

1. Scope

This appendix lists items supplied for ini-tial operation. The list includes tools, parts,and material issued as part of the major enditem. The list includes all items authorizedfor basic operator maintenance of the equip-ment. End items of equipment are issued onthe basis of allowances prescribed in equip-ment authorization tables and other documentsthat are a basis for requisitioning.

2. Columnsa. Source, maintenance, and recoverabil i ty

code. Not used.

b. Federal stock number. This column liststhe n-digit Federal stock number.

c. Designation by model. Not used.

d. Description. Nomenclature or the stand-ard item name and brief identifying data foreach item are listed in this column. When req-

uisitioning, enter the nomenclature and de-scription.

e. Unit of issue. The unit of issue is eachunless otherwise indicated and is the supplyterm by which the individual item is countedfor procurement, storage, requisitioning, al-lowances, and issue purposes.

f. Expendability. Nonexpendable items areindicated by NX. Expendable items are notannotated.

g. Quantity authorized. Under “Items com.prising on Operable Equipment,” the columnlists the quantity of items supplied for theinitial operation of the equipment.

h. Illustration. The “Item No.” column liststhe reference designations that appear on thepart in the equipment. These same designa-tions are also used on any illustrations of theequipment. The numbers in the “Figure No. ”column refer to the illustrations where the partis shown.

8

APPENDIX VI (Added)

MAINTENANCE ALLOCATION FOR DYNAMOTOR DY-107/AR; DY-107A/AR


1. General

a. This appendix assigns maintenance func-tions to be performed on Components, assem-blies, and subassemblies by the lowest appro-priate maintenance echelon.

b. Columns in the maintenance allocationchart are as follows:

(1) Component. This column shows onlythe nomenclature or standard itemname. Additional descriptive data isincluded only where clarification isnecessary to identify the component.Components, assemblies, and subas-semblies are listed in top-down order.That is, the assemblies Which are partof a component are listed immediatelybelow that component and the subas-semblies which are part of an assem-bly. Each generation breakdown (corn.ponents, assemblies, or subassemblies)are listed in disassembly order oralphabetical order.

(2) Maintenance function. This columnindicates the various maintenancefunctions allocated to the echelons.

(a)

(b)

(c)

(d)

(e)

( f )

Service. To clean, to preserve, andto replenish lubricants.

Adjust. To regulate periodically toprevent malfunction.

Inspect. To verify serviceabilityand to detect incipient electrical ormechanical failure by scrutiny.Test. To verify serviceability andto detect incipient electrical or me-chanical failure by use of specialequipment such as gages, meters,etc.Replace. To substitute serviceablecomponents, assemblies, or subas-semblies, for unserviceable compo-nents, assemblies, or subassemblies.Repair. To restore an item to serv-iceable condition through correc-

(9)

(h)

(i)

( j )

tion of a specific failure or unserv-iceable condition. This function in-cludes but is not limited to welding,grinding, riveting, straightening,and replacement of parts other thanthe trial and error replacement ofrunning spare type items such asfuses, lamps, or electron tubes.

Align. To adjust two or more com-ponents of an electrical system sothat their functions are properlysynchronized.

Calibrate. To determine, check, orrectify the graduation of an instru-ment, weapon, or weapons system,or components of a weapons system.Overhaul. To restore an item to com-pletely serviceable condition as pre-scribed by serviceability standardsdeveloped and published by heads oftechnical services. This is accom-plished through employment of thetechnique of “Inspect and RepairOnly as Necessary” (IROAN). Max-imum utilization of diagnostic andtest equipment is combined withminimum disassembly of the itemduring the overhaul process.Rebuild. To restore an item to astandard as near as possible to orig.inal or new condition in appearance,performance, and life expectancy.This is accomplished through themaintenance technique of completedisassembly of the item, inspectionof all parts or components, repair orreplacement of worn or unservice-able elements using original manu-facturing tolerances and/or speci-fications and subsequent reassemblyof the item.

(3) Ist, 2d, 3d, 4th, 5th echelon. The sym-bol X indicates the echelon responsiblefor performing that particular main-tenance operation, but does not neces-

10

(4)

(5)

sarily indicate that repair parts willbe stocked at that level. Echelonshigher than the echelon marked by Xare authorized to perform the indi-cated operation.

Tools required. This column indicatescodes assigned to each individual toolequipment, test equipment, and main-tenance equipment referenced. Thegrouping of codes in this column of themaintenance allocation chart indicatesthe tool, test, and maintenance equip-ment required to perform the mainte-nance function.

Remarks. Entries in this column areused to clarify any of the data cited in the pre-ceding column.

c. Columns in the allocation of tools for main-tenance functions are as follows:

(1)

(2)

(3)

Tools required for maintenance func-tions. This column lists tools, test, andmaintenance equipment required toperform the maintenance functions.

Ist, 2d, 3d, 4th, 5th echelon. The dag-ger (~) symbol in these columns indi-cates the echelons normally allocatedthe facility.

Toot code. This column lists the toolcode assigned.

2. Maintenance by Using Organizations

When this equipment is used by signal serv-ices organizations organic to theater headquar-ters or communication zones to provide theatercommunications, those maintenance functionsallocated up to and including fourth echelon areauthorized to the organization operating thisequipment.

11

APPENDIX Vll (Added)

BASIC ISSUE ITEMS LIST FOR DYNAMOTOR DY-107/AR; DY-107A/AR

Section L INTRODUCTION

1. Scope

This appendix lists items supplied for initialoperation. End items of equipment are issuedon the basis of allowances prescribed in equip-ment authorization tables and other documentsthat are a basis for requisitioning.

2. Columns

a. Source, Maintenance and RecoverabilityCode. Not used.

b. Federal Stock Number. This column liststhe n-digit Federal stock number.

c. Designation By Model. Not used .

d. Description. Nomenclature or the standarditem name and brief identifying data for each

item are listed in this column. When requisition-ing, enter the nomenclature and description.

e. Unit of Issue. The unit of issue is each un-less otherwise indicated and is the supply termby which the individual item is counted for pro-curement, storage, requisitioning, allowances,and issue purposes.

f. Expendability. Nonexpendable items areindicated by NX. Expendable items are not an-notated.

g. Quantity Authorized. Under “Items Com-prising an Operable Equipment,” the columnlists the quantity of items supplied for the ini-tial operation of the equipment.

h. Illustration. The “Figure No.” columnlists the figure and reference numbers used foridentification of the items in the illustration.

14

BY ORDER OF THE SECRETARY OF THE AR M Y:

Official:J. C. LAMBERT,

Major General, United States Army,The Adjutant General.

G. H. DECKER,General, United States Army,

Chief of Staff.

Distribution:

Active Army & USAR:

To be distributed in accordance with DA Form 12-31 requirements for Operator and Crew Maintenance

Instructions for all Fixed and Rotor Wing Aircraft.

NG: None.

16U. S. GOVERNMENT PRINTING OFFICE , 1965 0- 769-102 (2770)

8 2 4 - 3 2 6

TM 11-5821-204-12*C2

TECHNICAL MANUAL

Operator’s and Organizational Maintenance ManualRADIO SET AH/ARC-44

TM 11-5821-204–12 HEADQUARTERS,DEPARTMENT OF THE ARMY

CHANGES No. 2 WASHINGTON 25, D. C., 25 May 1962

TM 11–5821–204–12, 30 November 1960, is changed as follows:

Page 5, paragraph 2. (as changed by C 1, Support Agency, ATTN: SIGMS-ML, Fort27 Jun 61) Delete subparagraph d and substi- Monmouth, N. J.tute the following:

Page 37, (as deleted by C 1, 27 Jun 61). De-al. Comments or Suggestions. Any com- lete all reference to TM 11–5965-215-15P.

ments concerning omissions and discrepanciesin appendixes II thru VII will be prepared on Change TM 11-6125–204–12P to read: TMDA Form 2028 and forwarded direct to Com- 11–6125-207-12P, (as changed by C 1, 27manding Officer, U. S. Army Signal Materiel Jun 61).

APPENDIX II (Superseded)

MAINTENANCE A11 OCATION RADIO SET


1. Generala. This appendix assigns maintenance func-

tions to be performed on components, assem-blies, and subassemblies by the lowest appro- (2)priate maintenance echelon.

b. Columns in the maintenance allocationchart are as follows: (a)

(1) Component. This column shows onlythe nomenclature or standard item (b)name. Additional descriptive data isincluded only where clarification isnecessary to identify the component. (c)

Components, assemblies, and subas-semblies are listed in topdown order.That is, the assemblies which are part (d)of a component are listed immediatelybelow that component and the subas-semblies which are part of an assem-bly. Each generation breakdown (com-

AN/ARC-44

ponents, assemblies, or subassemblies)are listed in disassembly order or al-phabetical order.

Maintenance function. This columnindicates the various maintenancefunctions allocated to the echelons.

Service. To clean, to preserve, andto replenish lubricants.

Adjust. To regulate periodically toprevent malfunction.

Inspect. To verify serviceabilityand to detect incipient electrical ormechanical failure by scrutiny.

Test. To verify serviceability andto detect incipient electrical or me-chanical failure by use of specialequipment such as gages, meters,etc.

● These changes supersedes C1, 27 June 1961.

1

(e)

(f)

(9)

(h)

(i)

( j )

Replace. To substitute serviceablecomponents, assemblies, or subas-semblies, for unserviceable compo-nents, assemblies, or subassemblies.

Repair. To restore an item to serv-iceable condition through correctionof a specific failure or unserviceablecondition. This function includesbut is not limited to welding, grind-ing, riveting, straightening, and re-placement of parts other than thetrial and error replacement of run-ning spare type items such as fuses,lamps, or electron tubes.

Align. To adjust two or more com-ponents of an electrical system sothat their functions are properlysynchronized.

Calibrate. To determine, check, orrectify the graduation of an instru-ment, weapon, or weapons system,or components of a weapons system.

Overhaul. To restore an item to com-pletely serviceable condition as pre-scribed by serviceability standardsdeveloped and published by heads oftechnical services. This is accom-plished through employment of thetechnique of “Inspect and RepairOnly as Necessary” (IROAN). Max-imum utilization of diagnostic andtest equipment is combined withminimum disassembly of the itemduring the overhaul process.

Rebuild. To restore an item to astandard as near as possible to orig-inal or new condition in appearance,performance, and life expectancy.This is accomplished through themaintenance technique of completedisassembly of the item, inspectionof all parts or components, repair orreplacement of worn or unservice-able elements using original manu-facturing tolerances and/or specifi-

(3)

(4)

(5)

cations and subsequent reassemblyof the item.

Ist, 2d, 3d, 4th, 5th echelon. The symb-ol X indicates the echelon responsiblefor performing that particular main-tenance operation, but does notnecessarily indicate that repair partswill be stocked at that level. Echelonshigher than the echelon marked by Xare authorized to perform the indi-cated operation.

Tools required. This column indicatescodes assigned to each individual toolequipment, test equipment, and main-tenance equipment referenced. Thegrouping of codes in this column of themaintenance allocation chart indicatesthe tool, test, and maintenance equip-ment required to perform the mainte-nance function.

Remarks. Entries in this column willbe utilized when necessary to clarifyany of the data cited in the precedingcolumn.

c. Columns in the allocation of tools for main-tenance functions chart are as follows:

(1) Tools required for maintenance func-tions. This column lists tools, test, andmaintenance equipment required toperform the maintenance functions.

(2) lst, 2d, 3d, 4th, 5tlt echelon. The dag-ger (t’ ) symbol in these columns indi-cates the echelons normally allocatedthe facility.

(3) Tool code. This column lists the toolcode assigned.

2. Maintenance by Using Organizations

When this equipment is used by signal serv-ices organizations organic to theater headquar-ters or communication zones to provide theatercommunications, those maintenance functionsallocated up to and including fourth echelon areauthorized to the organization operating thisequipment.

2

TECHNICAL M ANUAL}No. 11-5821-204–12

● TM 11-5821-204-12

HEADQUARTERS,DEPARTMENT OF THE ARMY

W A S H I N G T O N 25, D.C. , 90 November 1960

RADIO SET AN/ARC44

C H A P T E R 1 . INTRODUCTION

CHAPTER 2. OPERATING INSTRUCTIONS

Section I. ControlsINT signal distribution panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .FM control panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . .P o w e r s w i t c h e s a n d c o n t r o l s

II. Operating instructionsTypes of operation . . . . . . . . . . . . . . . . . .Starting procedure . . . . . . . . . .I n t e r p h o n e o p e r a t i o nFm liaison set operation .

Paragraph

12

3456789

10111213141516

171819

20212223

Page

55

5788999

13131414151617

192020

21212121

*TM 11-5821-204-12 supersedes the following publications: TM 11-517, 4 December 1956, including Cl, 1July 1957; C2, 22 July 1957, C3, 21 January 1958, and C4, 7 April 1959, as applies to operator’s and organiza-tional maintenance. TM 11-5821-204–12P, 23 July 1959, including Cl, 28 June 1960. TM 11–5821-200-15P, 2 De-cember 1958 as applies to the first echelon portion and the maintenance allocation chart.

1

C H A P T E R 3 ,

C H A P T E R 4 .

C H A P T E R 5 .

Chapter 6 .

A P P E N D I X I .

II.

111.

I v .

v .

PREFLIGHT (DAILY) INSPECTIONGeneral . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Inspections for all flights . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Preflight inspection, power on . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

ORGANIZATIONAL MAINTENANCEScope of organizational maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Tools and test equipment required . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Preventive maintenance techniques . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Preventive maintenance instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Equipment performance checklist . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Maintenance of dynamotor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Removal and replacement of fm liaison set . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Fm receiver-transmitter squelch adjustment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

AUXILIARY EQUIPMENTIntroduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Switch Assembly SA-474/AR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Antenna Group AN/ARA-31 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

DEMOLITION OF MATERIEL TO PREVENT ENEMY USEAuthority for demolition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Methods of destruction .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

REFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

242526

2728293031323334

353637

3839

. . . . . . .

MAINTENANCE ALLOCATION CHART FOR RADIO SETAN/ ARC-44 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

BASIC ISSUE ITEMS LIST FOR RADIO SET AN/ARC-44 . . . . . . . . . . . .

BASIC ISSUE ITEMS LIST FOR ANTENNA AT-454/ARC ..........................

MAINTENANCE ALLOCATION CHART FOR ANTENNAAT-454/ARC. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Page

232323

2525252525292931

323337

3636

37

38

51

55

57

2

reported to a higher echelon using forms and pro- listed in the periodic maintenance inspection chartcedures specified by TM 38-750. Equipment that (par. 30.4) in the sequence listed. Whenever ahas a deficiency that cannot be corrected by second normal condition or result is not observed, takeechelon maintenance should be deadlined in accord- corrective action in accordance with the paragraphance with TM 38–750. Perform all the services listed under references.

30.4 Periodic Maintenance Service and Inspection Chart

Note. Omit items 12 through 19 if the AN/ARC-44 does not have the auxiliary equipments AN/ARA-31 and SA-474/AR.

1

2

3

4

5

6

7

8

9

10

11

Procedure

Item

SET: Inspect the equipment for-u. Completeness . . . . . . . . . . . . . . . . . . . . . . . . .b. Proper installation . . . . . . . . . . . . . . . . . . . .

c. Cleanliness . . . . . . . . . . . . . . . . . . . . . . . . .

d. Preservation . . . . . . . . . . . . . . . . . . . . . . . . .

PUBLICATIONS: Check to see that perti-nent publications are available (app. I).

MODIFICATION WORK ORDERS: CheckDA Pam 310-4 to determine if new appli-cable MWO’S have been published.

FUSES: Check for proper fuses (F101 andFI02) in Dynamotor DY-107(*)/AR.

BRUSHES: Inspect dynamotor brushes andbrush caps.

MOUNTING: Inspect for seating, stability,loose or missing hardware of all mountings.

CONNECTIONS: Check the connections ofall cables interconnecting the componentsof the equipment, including the headset-microphone and antenna connections.

KNOBS, DIALS, AND SWITCHES: Checkfor proper mechanical action by setting eachcontrol to each of its possible settings.

ANTENNA: Inspect, Antenna AT-454(*)/ARC.

OPERATIONAL CHECK: Perform completeoperational check of the AN/ARC-44 inaccordancc with paragraph 31.

SQUELCH ADJUSTMEN’I’: Adjust SQUELCH control on the fm rcceiver- transmitter in accordance with paragraph

34.


a. Equipment must be complete. -.. . . . . . . . . . . .b. Installation is in accordance with the manual

covering the aircraft in which the set is in-stalled.

c. Units must be clean and dry inside and out;free of grease ,dirt, rust, corrosion, and fungus.

d. Painted surfaces must be free of bare spots,rust, and corrosion.

a. Operator’s and organizational maintenancemanual must be complete and in usable condi-tion without missing pages.

b. All Changes pertinent to the equipment areon hand (DA Pam 310-4).

ALL URGENT MWO’S have been applied tothe equipment.

ALL ROUTINE MWO’S have been scheduled.There should be two 1/2-ampere, 250-volt, 3AG

type fuses.Brushes not chipped, broken, or worn to brush

wear line.All components securely mounted in place. No

nuts, bolts, or other fasteners loose or brokenon mountings. All bonding straps properlygrounded and units properly safety wired.

Connections not loose and connectom properlyfitted into their respective receptacle andclean. Cables not frayed.

Action is positive without backlash, binding, orscraping.Note: Knobs that require frequent tightening should

have setscrews replaced if they show signs of wear.Antenna is complete with whip, base, and

coupler, Whip is securely attached to baseand tiltcd 15°, and base is secured to aircraftsurface. No kinks in whip.

Equipment operates normally from the pilot andcopilot positions.

Background noise in the headset is adjusted to acomfortable level.

Reference

a. Par. 5.b. Configuration


c. Par. 29.

a. App. I.

b. DA Pam 310-4 forrequirements.

DA Pam 310-4.

Fig, 6.

Par. 32.

Par. 33b.

a. Fig. 2.b. Configuration


Pars, 17-23.

Par, 12.

a. Par. 31.b. Organizational

maintenancemanual of appli-cable aircraft.

Par. 34.

TAGO 7998-A 3

No.

Item

12

13

14

15

16

17

18

l9

Procedure

Item

AUXILIARY EQUIPMENT: Inspect An-tenna Group AN/ARA-31 and Switch As-sembly SA-474/AR for-

a. Completeness ------------------------

b. Proper installation -------------------

c. Cleanliness . . . . . . .. . . . . . . . . . . . .

d. Preservation ------------------------

PUBLICATIONS: Check to see that perti-nent publication for the AN/ARA-31 andSA-474/AR arc available.

MODIFICATION WORK ORDERS: CheckDA Pam 310-4 to determine whether newapplicable MWO's have been publishedcovering the AN/ARA-31 and SA–474/AR.

MOUNTING: Inspect for seating, stability,loose or missing hardware of all mountings.

CONNECTIONS: Check the connections ofall cables interconnecting the componentsof Antenna Group AN/ARA-31, SwitchAssembly SA-474/AR, and Radio Set AN/ARC-44.

SWITCHES: Check the toggle switches onSwitch Assembly SA-474/AR for propermechanical action by setting each switch toeach of its positions.

ANTENNA: Inspect installation of AntennaElement AT-624 (•)/.AR on aircraft.

OPERATIONAL CHECK: Perform completeoperational check of the AN/ARA-31, SA–474/AR, and AN/ARC-44, as a homingfacility in accordancc with paragraph 37b.


a. Equipment must complete------------

b. Installation is in accordance with organiza-tional maintenance manual covering the air-craft in which set is installed.

c. Units must be clean and dry inside and out;free of grease, dirt, rust, corrosion, and fungus.

d. Painted surface must be free of hare spotsj

rust, and corrosion.a. Operator’s and organizational maintenance

manual (TM 11-5985-200-12) must becomplete and in usable condition withoutmiming pages.

b. All Changes pertinent to the equipment are onhand (DA Pam 310-4).

ALL. URGENT MWO’S have been applied tothe equipment.

ALL ROUTINE MWO’S have been scheduled.

.411 components securely mounted in place. Nonuts, bolts, or other fasteners loose or brokenon mountings.

Connections not loose and connectors properlyfitted into their respective receptacles andclean.

Action is

Cables not frayed.

positive, without binding or sticking.

The two Antenna Elements AT-624(*)/AR areproperly installed and complete with Network,Impedance Matching CU-459/AR. Fiber-glass whip of Antenna Element AT-624A/ARis not loose or detached from metal base orconductor.

Equipment operates normally as a homingfacility.

a. TM 11-5985-200-12.


a. App. I, TM 11-598-200-12.

b. DA Pam 310-4for requirements

DA Pam 310-4.

a. TM 11-5985–200-12.


Configurationmanual of appli-cable aircraft.

Par. 36.

a. TM 11-5985-200-12.


Par. 37b.

Page 32, figure 13, caption. Change “SA-464/ Record System and Pro-AR” to: SA-474/AR. cedures.

Page 39, paragraph 35c. After “AN/ARA-31 ,“TM 11–5985-200-12 operator’s and Organiza-

tional Maintenanceadd: and Switch Asscmbly y SA–474/AR. Manual: Antenna Group

Page 37. Add the following to the appendix. AN/ARA-31 and SwitchTM 38-750 The Army Equipment Assembly SA474/AR.

4 TAGO 7998-A

By Order of the Secretary of the Army:

Official:

W. C, WESTMORELAND,General, United States Army,Chief of Staff

VERNE L. BOWERS,Major General, United States Army,The Adjustment General

Distribution:To be distributed in accordance \vith DA Form 12-36, (qty rqr block no. 377) Operator maintenance re-quirements for all Fixed and Rotor Wing aircrafts.

*U.S. GOVERNMENT PRINTING OFFICE : 1992-311-831 (44820)

3

P I N : 022912-004

By Order of the Secretary of the Army:

Official:J. C. LAMBERT,Major General, United States Army,The Adjutant General

EARLE G. WHEELER,General, United States Army,Chief of Sta.ff.

Distribution:To be distributed in accordance with DA Form 12-31 requirements for Operator and Organizational Maintenance Instruc-

tions for All Fixed and Rotor Wing aircraft.

* U.S. GOVERNMENT PRINTING OFFICE: 1992 - 311-831 (43948)

TAGO 7998-A

CHAPTER 1

INTRODUCTION

Section 1. GENERAL

1. Scopea. This manua l desc r ibes Rad io Se t

AN/ARC–44 (fig. 1 ) and covers the operatinginstructions to be used by the aircraft pilot,operator’s preflight inspections, and organiza-tional maintenance procedures to be performedby the organizational repairman or the crewchief.

b. Nomenclature followed by (*) is used toindicate all models of the equipment coveredin this manual. Thus, Receiver-Transmitter,Radio RT–294(*)/ARC–44 represents Re-ceiver-Transmitters, Radio RT-294/ARC-44,RT-294A/ARC–44, and RT-294B/ARC-44.Mounting MT–1267(*)/AR represents Mount-ings MT-1267/AR and MT–1267Al/AR. An-tenna AT–454 (*)/ARC represents AntennasAT-454/ARC and AT–454A/ARC. Base, An-tenna AFL-340(*) ARC represents Base, An-tenna AB–340/ARC and Base , AntennaSupport AB-340A/ARC. Antenna ElementAT–455(*)/ARC represents Antenna Ele-ments AT–455/ARC and AT–455A/ARC. An-tenna Elements AT–624/(*)/AR representsAntenna Elements AT-624/AR and AT-624A/AR. Coupler, Antenna CU–361(*) ARCrepresents Couplers, Antenna CU-361/ARC,CU-361A/ARC, CU-361B/ARC, CU-361C/ARC, and CU--361D/ARC. Headset-Micro-phone H-101 (*)/U represents Headset-Micro-phones H–101/U and H–101A/U. DynamotorDY-107(*)/AR represents Dynamotors DY-107/AR and DY–107A/AR. Keyer KY-

149(’) AR represents Keyers KY-149/AR andKY-149A AR.

2. Forms and Recordsa. Unsatisfactory Equipment Reports. Fill

out and forward DD Form 787–1 (ElectronicFailure Report-Signal Equipment) to theCommanding officer, U. S. Army Signal Mate-riel Support Agency, ATTN: SIGMS-ML, FortMonmouth, N. J., as prescribed in AR 700–39.

b. Report of Damaged or Improper Ship-ment. Fill out and forward DD Form 6 (Re-port of Damaged or improper Shipment), asprescribed in AR 700–58.

c. Maintenance Forms. Prepare DD Form781–2 (Aircraft Flight Report and Mainte-nance Record, Aircraft Inspection and Mainte-nance) in accordance with the instructions onthe form. All preflight and postflight inspec-tions of Radio Set AN ARC-44 will be re-corded on this form.

d. Parts List Form. Forward DA Form2028 (Recommended Changes to DA TechnicalManual Parts Lists or Supply Manuals 7, 8,and 9) direct to the Commanding Officer, U. S.Army Signal Materiel Support Agency, ATTN :SIGMS-ML. Fort Monrnouth, N. J., with anycomments concerning omissions and discrep-ancies in appendixes II through V.

e. Comments on Manuals. Forward all othercomments concerning this publication directlyto the Commanding Officer, U. S. Army SignalMateriel Support Agency, ATTN: SIGMS-PA2d, Fort Monmouth, N. J.

Section Il. DESCRIPTION AND DATA

3. Purpose and Use range of Radio Set AN ARC–44 permits the(fig. 2) pilot or copilot of the aircraft to communicate

a. Radio Set AN/ARC–44 provides the with armored, artillery, and infantry units in

pilot and copilot with two-way communication the field, Radio Set AN/ARC–44 provides thesebetween aircraft and ground stations and air- communication facilities within the frequencycraft to aircraft within the tactical military range of 24 to 51.9 megacycles (me) on 280frequency-modulation channels. The frequency preset channels. The distance range is limited

5

Figure 2. Radio Set AN/ARC-44, functional block diagram.

to distances of approxi-

w i t h A n t e n n a G r o u p

to line of sightmately 50 miles.

up

b . W h e n u s e dAN/ARA-31 (para 37), Radio Set AN/ARC-44 provides the pilot with a homing facilitywhich will allow the pilot to home on any keyedunmodulated signal transmitted within thefrequency range of 24 to 49 mc.

c. Panel, Signal Distribution, Radio SB-329/AR amplifies and controls the routing anddistribution of audio signals applied to or fromHeadset-Microphone H–101 (*) /U from thenavigational sets and other communication setsas well as the Radio Set AN/ARC–44 audio.From Panel, Signal Distribution, Radio SB-329/AR the user may select any one of fivereceivers, singly or in combination, the air-craft interphone channel, or Radio SetAN/ARC-44 frequency modulation (fro) facil-ity or any of two other radio communicationfacilities that may be installed in the aircraft.

Note. TWO separate Panels, Signal Distribution,Radio SB-329/AR are used to provide intercommuni-cation and allow the pilot and copilot to use the elec-tronic facilities of the aircraft at their discretion.

d. Panel, Control SB–327 ARC-44 p r o -

vides for remote control of Receiver-Trans-mitter, Radio RT–294 ( * )/ARC-44. It allowsthe pilot or copilot to turn on Receiver-Trans-mitter, Radio RT–294 ( * ) /ARC-44, select itsfrequency of operation, and adjust the audiovolume level.

e, R e c e i v e r - T r a n s m i t t e r , R a d i o R T –294 ( * ) ,ARC-44 converts the audio generatedby the H-101(*)/U to a radiofrequency (rf)signal and vice versa. It receives and trans-mits on a common antenna, Antenna AT-454 (*)/ ARC, Coupler, Antenna CU-361 ( *) /ARC matches the impedance of Antenna AT-454 ( * ),/ARC to that of Receiver-Transmitter,Radio RT-294 ( * ) /ARC-44.

f. Dynamotor DY–107 ( * ) /AR generatesthe high-voltage, direct-current (de) and 400-cycle-per-second (cps) alternating-current (at)power for operation of Receiver-Transmitter,Radio RT-294 ( * )/ARC–44 and Panel, SignalDistribution, Radio SB–329/AR.

g. Switch Assembly SA-474/AR (para 36),although not part of Radio Set AN/ARC-44, isgenerally supplied with it. The SA-474/AR, orits equivalent, is used to turn on and off thesquelching action of Receiver-Transmitter,

6

Radio RT-294(* )/ARC-44. I f Rad io Se tAN/ARC–44 is used with Antenna GroupAN/ARA–31, Switch Assembly SA–474/AR isalso used to control the application of power toAntenna Group AN/ARA–31.

h. Terminal Box J-562/AR, or its equiv-alent, is used to interconnect the operatingcomponents of Radio Set AN/ARC-44 andprovides for the distribution of primary power,dynamotor power, and interconnection of audiofacilities.

Note. Radio Set AN/ ARC44 is installed in aircraftof which the signal configuration may vary and, there-fore, the components and interconnecting cabling willnot always be the same. For data on the individualaircraft wiring and cabling, reference should be madeto the organizational maintenance manual covering theaircraft.

4. Technical Characteristics of Radio SetA N / A R - 4 4

a. R e c e i v e r - T r a n s m i t t e r , R a d i o R T -2 9 4 ( * ) / A R C - 4 4 a n d

Frequency range . . . . . . . . . .

Number of tubes . . . . . . . . . .Power source . . . . . . . . . . . . . . . .

Power input frombattery to RT-294(*)/ARC-44.

Power input fromDynamotor DY-107(*)/AR toReceiver-Trans-mitter, RadioRT-294(*)/ARC-44 . . . . . . . . . . . . . .

Mounting MT-1268/AR.

280 preset channels, 24.0 to51.9 mc; channel separa-tion, 100 kc.

29.27.5 vdc aircraft electrical

system and DynamotorDY-107(*)/AR.

27.6 vdc, 3 amp.

150 vdc (B+), 85 ma.300 vdc (B+), 125 ma.27 vac at 400 cps.

(1) Tramsmitter .Type of modulation . . . . Fm, using reactance-tube

modulation.Type of signals trans-

mitted . . . . . . . . . . . . . . . . . . . . . . . . . . Voice.Distance range . . . . . . . . . . . . . . 50 miles.l

Power output:RT-294/ARC-44 . . 6 watts, 62 ohms resistive

load.RT-294A / ARC-44. 8 watts, 52 ohms resistive

load.

1 The range will vary conidercbly according to tbe terrain,atmospheric conditions, and the altitude of the aircraft.

RT-294B/ARC-44. 8 watts, 52 ohms resis t ive

Audio preemphasis . . . . . .

Frequency deviation . . . .

Sidetone output level . .

(2) Receiver.Receiver type . . . . . . . . . . . . . . . .

Types of signals thatcan be received . . . . . . . .

Sensitivity . . . . . . . . . . . . . . . . . . . .

Selectivity . . . . . . . . . . . . . . . . . . . . . .

Audio power output . . . .Image rejection . . . . . . . . . .First if. . . . . . . . . . . . . . . . . . . . . . . . . . .

Second if. . . . . . . . . . . . . . . . . . . . . .Audio reemphasis . . . . . . . .

load.With input voltage to pre-

emphas is ne twork con-s t a n t , o u t p u t v o l t a g eincreases linearly (within

tave rate from 1,000 to6,000 cps. The output volt-age does not decrease morethan 4 db at 500 cps normore than 6 db at 250 cpsfrom the measurement at1,000 cps.

+20 kc at 1,000 cps (nom-inal) ; +35 kc (maximum).

10 mw to 40 mw (150 ohmsload).

Double-conversion super-heterodyne.

Fm voice, squelch control,and when used as a hom-ing receiver, keyed unmod-ulated signals.

1 # v for 10-db signal-plus-noise to noise;

10 # v for 40-db signal-plus-noise to noise, using 62ohms signal generator.

Minimum, 75-kc bandwidthat 6 db.

Maximum, 300-kc bandwidthat 60 db.

60 .nw across 160 ohms.60 db minimum.6.55 to 7.45 mc (variable in

0.1-mc steps).2.9876 mc (fixed).With input voltage to deem-

phasis network constant,output voltage decreaseslinearly (within ±2 db) ata 2-db-per-octave ratefrom 1,000 to 6,000 C P S.The output voltage doesnot increase by more than4 db at 600 cps northan 6 db at 250 cpsthe measurement atCps.

b. Panel, Signal Distribution, Radio3 2 9 / A R .

Number of tubes . . . . . . . . . . 5.Power input from dy-

namotor . . . . . . . . . . . . . . . . . . . . . . 150 vdcPower input from bat-

tery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27.5 vdc

(B+) 23 ma.

(filament) 360

morefrom1,000

S B -

ma.

7

Headset amplifier ,out-put . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 200 mw into 8-ohms resistive

load (2.5-volt input).Headset amplifier fre-

quency response . . . . . . +1 to – 3 db from 1,000-cpsreference signal in the 300to 6,000-cps range.

Microphone amplifieroutput . . . . . . . . . . . . . . . . . . . . . . . . 3 volts across 2 ,700 o h m s

( 0.6-mv input).Microphone ampIifier

frequency response . . + 1 to – 3 db from 1,000-cpsreference signal in the 300to 6,000-cps range.

Interphone sidetoneoutput . . . . . . . . . . . . . . . . . . . . . . . . 50 mw.

c. Dynamotor DY–107(*)AR and Mount-ing MT–1267(*)/AR.Power input from bat-

tery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.75 amp maximum at 27.5

Ouantity

112

1

2

111

1

1

1

3

1

vdc.

Power output . . . . . . . . . . . . . . 140 ma at 150 vdc; 125 maat 300 vdc; 27 vac at 400cps.

Average operatingspeed . . . . . . . . . . . . . . . . . . . . . . . . . . 8,000 rpm.

d . An tenna AT-454(* ) /ARC.

Type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Whip ( transmitting and re-ceiving).

Frequency range of op-eration . . . . . . . . . . . . . . . . . . . . . . . . 24.0 to 51.9 mc.

Length (overall) . . . . . . . . 8.2 feet.

Maximum VSWR . . . . . . . . 4 to 1.

5. Components of Radio Set AN/ ARC-44(fig. 1)

The components of Radio Set AN/ARC-44are listed in the following chart:

Receiver-Transmitter, Radio RT-294(*)/ARC-44 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Panel, Control SB-327/ARC-44 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Panel, Signal Distribution, Radio SB-329/AR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Dynamotor DY-107( *)/AR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Headset-Microphone H-101 (*)/U

Antenna AT-454(*)/ARC, consisting of:

Coupler, Antenna CU-361 (*)/ARC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Antenna Element AT-455(*)/ARC. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Base, Antenna AB-340 (*) /ARC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Mounting MT-1268/AR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Mounting MT-1267 (*)/AR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Connector, receptacle, electrical FSN 5935-201-7935

Connector, receptacle, electrical FSN 5935-642–5387

Connector, receptacle, electrical FSN 5935-643-6904

7.24

3.00

2.625

5.37

1.6191.864.36

1.73

1.31

6. Nomenclature and Common NamesTo simplify textual references, common

names are frequently used in place of thecomplete nomenclature. A list of the commonname assignments is given below.

Nomenclature

Radio Set AN/ARC-44 . . . .Receiver-Transmitter, Ra-

dio RT-294 ( ● )/ARC-44Mounting MT-1268/AR . .

Common names

Fm liaison set

Fm receiver-transmitterReceiver-transmitter

mounting

Panel, ControlSB-327/ARC-44

DynamotorDY-l07(*)/AR

Mounting MT-1267(*)/AR

Panel, Signal DistributionRadio SB-329/AR

Terminal Box J-562/AR ..

13.90

6.06

5.30

9.22

3.06

3.18

11.80

9.31

5.13

5.75

5.75

3.40

2.04

5.80

6.00

3.31

14

2.19

1.63

6

0.630.751.50

0.87

0.81

FM control panel

Dynamotor

Dynamotor mounting

INT signal distributionpanel

Terminal box

8

Nomenclature

Antenna AT-454(*)/ARCconsisting of:

Coupler, AntennaCU-361(*)/ARC

Antenna ElementAT-455 (*) / ARC

Base, AntennaAB-340(*)/ARC

Headset-MicrophoneH-101(*)/U

Switch AssemblySA-474/AR

Antenna GroupAN/ARA-31

Connector, Receptacle,Electrical FSN 5935-643-6904



Communication antenna:

Coupler

Whip

Base

Headset-microphone

Switch panel

Antenna group

Receiver-transmitter con-nector

Panel connector

Dynamotor connector

7. Description of Radio Set AN/ARC-44a. The fm liaison set (fig. 1) includes an

fm receiver-transmitter and its mounting, twoINT signal distribution panels, an FM controlpanel, a dynamotor and its mounting, a switchpanel, an antenna system, and a headset-micro-phone. The interconnecting cables and termi-nal box to which all the components areconnected are supplied as part of the aircraftin which the set is installed.

b. The components of the fm liaison set aresecured to mounting surfaces within the air-craft. From the mountings and panel con-nectors, connections are made to the aircraftbattery and components of the fm liaison set.The coaxial-cable connection to the antenna ismade either directly from the front panel ofthe fm receiver-transmitter or through thekeyer if Antenna Group AN/ARA–31 is used.For location of equipment, refer to the applica-ble aircraft signal electronic configurationtechnical manual.

8. Description of Receiver-Transmitter,Radio RT-294(*)/ARC-44

(fig. 3)

a. The fm receiver-transmitter is a sepa-

rately housed unit containing the receiver andtransmitter circuits of the fm liaison set. Ahandle is attached to the unit to provide con-venient handling. Behind the handle is ahinged door that covers carrier test switchS807 and test jack J809. SQUELCH andHOMING controls are externally accessible andare located above the handle on the left sideof the front panel. These two controls areprotected by a sliding panel that can be man-ually raised by moving the slide buttonadjacent to the controls.

b. The outlet for the fm receiver-transmit-ter exhaust fan is located at the rear of theunit on the rear cover, When installed, the fmreceiver-transmitter is secured in place on itsmount. The receiver-transmitter connector(Federal stock No. 5935-643-6904 (fig. 1)), isfastened to the rear of the MT-1268 / AR.Mating plug P815 on the rear of the fmreceiver-transmitter (fig. 3) is attached to thereceiver-transmitter connector when the fmreceiver-transmitter is placed on the MT–1268/AR.

c. The fm receiver-transmitter (fig. 3) isheld in place on the MT–1268/AR by two guidepins and two mounting screws. The groundstraps provide an electrical connection betweenthe mounting shelf and the bottom plate of theMT–1268/AR. This assures a good groundconnection in an installation. The vibrationisolators (shock mounts) on the MT–1268/ARprotect the fm receiver-transmitter from vi-bration and shock.

9. Description of Panel, ControlSB-327/ARC-44

(fig. 4)

a. The FM control panel is a separatelyhoused unit containing a VOL control, a REM-LOCAL selector switch, an ON-OFF switch,and concentrically mounted frequency selectorswitches (ring and knob), combined with aFREQ indicator window. An escutchen platecovers the frequency selector ring and knoband provides the viewing window for the fre-quency selected. It is held in place by twoescutchen mounting screws. The outer ring ofthe frequency selector switch rotates to show,one at a time, the whole numbers from 24through 51 in the top of the FREQ window.The center frequency selector switch (knob)

9

Figure 3. Reciever-Transmitter, Radio RT-294(*)/ARC-44 and Mounting MT-1268/AR.

10

Figure 4. Panel, Control SB-327 / ARC-44.

by four Dzus (quick-disconnect) fasteners at The spring lock fasteners on the panel connec-the corners of the front panel. The cover istor (fig. 1) secure the panel connector (Federalheld in place by a spring lock cover fastener. stock No. 5935–642–5387 ) to springlock recep-All external connections are made to the reartacles on the rear of the FM control panelof the FM control panel through jack J201. (fig. 4).

11

10. Description of Panel, Signal Distribution,Radio SB-329/AR

(fig. 5)

a. The INT signal distribution panel is aseparately housed unit which has five receiverselection switches, marked RECEIVERS 1, 2,3, MB, and NAV, and a TRANS selectorswitch. The TRANS selector switch is a four-position switch marked INT, 1, 2, and 3. Theseappear one at a time in the window above theTRANS selector switch. The position numberscorrespond to the numbers on the RECEIVERSswitches. An escutchen plate, mounted on thefront panel, provides a viewing window forthe TRANS selector switch.

b. Panel lights edge-light the clear plasticpanel so that the numerals light up red andare clearly visible and well-contrasted againsta dark background, All electrical wiring ismade through J301 located at the rear of theINT signal distribution panel.

c. The INT signal distribution panel isflush mounted by four quick-disconnect fasten-ers on the sides of the front panel. The springlock receptacles mate with the spring lockfasteners on the panel connector (Federalstock No. 5935–642–5387 (fig. 1 ) ) that securethe panel connector to the rear of the INTsignal distribution panel (fig. 5). The top andbottom covers are secured to the INT signaldistribution panel by mounting screws.

11. Description of DynamotorDY-107(*)/AR

a. The dynamotor (fig. 6) consists of adynamotor subassembly mounted on an electri-cal equipment chassis. The chassis containsthe various line filter components, fuses, anda voltage booster relay. Two output circuitfuses are readily accessible at the front of thechassis. Three pairs of dynamotor brushes aremounted at accessible positions on the dyna-

Figure 6. Dynamotor DY-107(*)/AR

Figure 7. Mounting MT-1267(*)/AR.

motor subassembly (three on each side). Thecontrol and power connections to the dynamo-tor are made at the rear of the unit at P101.Two mounting screws at the front of the elec-trical equipment chassis secure the dynamotorto its mounting.

b. Mounting MT-1267(*)/AR (fig. 7) se-cures the dynamotor in place in an installation.The dynamotor slides onto the mount guidedby the guide rail and is secured into place onthe mounting shelf by the guide pins. Thedynamotor is held in place by fastening themounting screws (a above) so that they lockinto the mounting screw inserts. The cableclamp on the dynamotor mounting preventsthe dynamotor power cable from pulling loose.

12. Description of Antenna AT454(*)/ARC(fig. 8)

The communication antenna consists of awhip, a base, and a coupler. The coupler iscon netted to the base by a coaxial cable. Thetapered whip is approximately 71/2 feet long.The whip screws into the antenna base and issecured by a setscrew and whip tightening nut.The base mounts the whip in a rigid positionand in such a manner that the whip is tilted15”. An insulating plate electrically separatesthe base from the aircraft mounting surface,and a gasket provides a watertight seal be-

14

tween the base and the mounting surface ofthe aircraft. A coaxial connector is mountedon the flat bottom portion of the base. Theantenna coupler has a removable plate foraccess to the internal components.

13. Description of Headset-MicrophoneH-101(*)/U

(fig. 9)

The headset-microphone provides for hand-free low-noise communication. The earphonesof the headset-microphone are provided withneoprene-covered padded cushions, designedfor the left and right ear, which are markedR (right) and L (left) on the rear outer sur-face of the cushions. The nylon earcap coverholds the cushion in place. A polyethylenemoisture barrier and black nylon guard areprovided over the microphone to protect it frommoisture and physical damage. The micro-phone with nylon guard is mounted on a swivelso that it may be placed directly in front ofthe lips when transmitting and moved asidewhen not in use. A nylon headband cover pro-tects the user’s hair from the headband. Theposition of the microphone with respect to thelips is adjusted with the swivel bracket adjust-ing screw. The headset-microphone plugs intothe communication system with Telephone PlugU-93 U or U-93A U.

F i g u r e 8 . A n t e n n a A T - 4 5 4 ( * ) / A R C .

14. Description of(fig. 1)

Connectors plastic dielectric connectors. The base of theconnectors is corrosive-resistant aluminum.The panel connectors are equipped with spring

a. Reciever-Transmitter Connector.. The re-ceiver-transmitter connector is a female,34-contact, 5-ampere, arc-resistant, plastic di-electric connector. it has two mounting studsof the friction-locking type. The connector isenvironment resistant.

b. Panel Connectors. The panel connectorsare female, 34-contact, 5-ampere, arc-resistant,

lock fasteners, two on each connector. Thesesecure the panel connectors to the unit \vithwhich they are used.

c. Dynamotor Connetors. The dynamotorconnector is a female, 20-contact, 5-ampere,arc-resistant, plastic dielectric connector. Ithas an aluminum, corrosive-resistant base andis of the friction-locking type.

15

Figure 9. Headset-Microphone H-101(*)/U.

15. Additional Equipment RequiredThe following items are not supplied as part

of the fm liaison set but are required for oper-ation. The items are supplied as part of theaircraft in which the fm liaison set is installed.

a. Switch Assembly SA-474/AR (fig. 13)or equivalent is used with Antenna GroupAN/ARA-31.

‘b. Terminal Box J–562/AR (fig. 10) orequivalent is required for interconnecting thecomponents of the fm liaison set.

c. The following cord and cable assembliesare required for interconnection or operationof the indicated components:

(1)

(2)

Electrical Cord Assembly CX-2555/Uwith a separately installed transmit-receive switch, or Electrical CordAssembly CX–2556/U with a trans-mit-receive switch, as part of the cableassembly.

Cables from the HOME switch on theswitch panel to Keyer KY–149 (* ) /ARand the terminal box if AntennaGroup AN/ARA–31 is installed.

(3) Cable RG-58C/U for connection be-tween the fm receiver-transmitter andKeyer KY–149 ( * ) /AR, coupler andKeyer KY–149/AR, and homing an-tennas and Keyer KY-149(*) /AR ifAntenna Group AN/ARA-31 is in-stalled.

d. When Antenna Group AN/ARA-31 isnot part of the installation, a separate squelchswitch is required. A single-pole, double-throwswitch mounted on the aircraft instrumentcontrol panel may be used for this purpose.

e. A source of power capable of supplying+27.5 volts dc at 10 amperes and providedwith a means of switching the power on andoff is required to operate the fm liaison set.This power is supplied by the aircraft in whichthe equipment is installed.

f. Circuit breakers (push-to-reset type) arerequired to protect the aircraft electrical sys-tem from overload.

g. Interconnecting cabling is required tointerconnect the operating components of theAN/ARC-44 within the aircraft. For the per-tinent details concerning this cabling, refer

16

to the applicable aircraft organizational main-tenance manual.

16. Differences in Modelsa. Receiver-Transmitter, Radio RT-294 (*)/

ARC-44. The external appearances of Re-ceiver-Transmitter, Radio RT-294/ARC-44,RT–294A/ARC–44, and RT–294B/ARC-44 areidentical. Operational procedures and organi-zational maintenance described in this manuaIapply equally to all models unless otherwisenoted.

b. Antenna AT-454(*)/ARC. The modifiedAntenna AT-454A/ARC consists of Base, An-tenna Support AB-340A/ARC, Antenna Ele-

ment AT-455A/ARC, and Coupler, AntennaCU-361A/ARC. Couple rs , Antenna CU-361 B/ARC, CU-361C/ARC, and CU-361D/ARC may also be used with Antenna AT-454A/ARC. Differences in models of thesecomponents are given below.

(1) Base, Antenna AB-340(*)/ARC.

(2) Antenna Element AT-455(*)/ARC.

AT-43S/ARC I AT-455A\ARC

Reuires a l-inch wrenchto unscrew the elementfrom the base. Threadedferrule is 1 % i n c h e slong.

Requires a 5/8-inch wrenchto unscrew the elementf rom the base . Baseof element is tapered.Threaded ferrule base is3 1/2 inches long.

L

Figure 10. Terminal Box J–562/ AR.

(3) Coupler , Antenna CU-361(*)/ARC.Couplers, Antenna CU-361/ARC,CU-361A/ARC, CU-361B/ARC, CU-361C/ARC, and CU-361D/ARC aresimilar in appearance and vary only incertain mechanical details of mount-ing electrical component. Differ-ences, where significant, and theinterchangeability of models are givenin the chart below:

Does not have pro-visions for safetywiring.

Has provisions forsafety wiring.

One-way inter-changeable withCU-361/ARC.


Two-way inter-changeable withCU-361A/ARC.


Interchangeable withCU-361/ARC,CU-361A/ARC,andCU-361B/ARC.


One-way interchange-able with all modelsof the coupler. Thismodel is capableof withstandinggreater vibration asencountered in heli-copters.

17

(’. D y n a m o t o r D Y - 1 0 7 ( * ) / A R . T h e e x -ternal differences between Dynamotors DY-107/AR and DY–107A/AR are given in thechart below.

DY-107/AR DY-107A/AR

Output voltage end cover Output voltage end coverhas four elongated cir- has two rows of holescular slots for ventila- on the outer circumfer-tion ports. ence to provide addi-

tional ventilation forcooling of dynamotor.

150 V.D.C. and 300 V.D.C. 150 V.D.C. and 300 V.D.C.fuses marked or rated fuses marked or ratedcm chassis as .5 A M P on chassis as 1/2 AMPfuses. fuses.

d. Headset-Microphone H-101(*)/U. Differ-ences between Headset-Microphones H-101/Uand H–101A/U are listed below.

H-101/U H-101A/U

Headset cord terminated Headset cord terminatedwith Plug, Telephone with Plug, TelephoneU-93/U. U-93A/U.

H-101/U H-101A/U

Microphone operating andrest (up) position pre-determined by detentstops; position of detentstops determined by set-ting of swivel bracketadjusting screw.

Microphone cord termi-nated in junction boxon headband.

Headband not readily hungon hook.

One adjustment of swivelbracket thumb nut per-mits microphone to beplaced in any position.

Microphone cord providedwith a quick-disconnectplug on headband.

Headband provided withstowing grommet to per-mit hanging on hook.

e. Mounting MT-1267(*)/AR. M o u n t i n gMT-1267A/AR differs from Mounting MT-1267/AR only in the position and length of theguide rail (fig. 7). On the MT-1267A/AR,the guide rail is located closer to the rear of themounting, and the lip of the guide rail hasbeen cut back approximately one-half inch.This decreases the distance required to slidethe dynamotor forward before it can be re-leased from the mounting.

18

CHAPTER 2

OPERATING INSTRUCTIONS

Section 1.

17. INT Signal Distribution Panel( f ig . 11)

Two INT signal distribution panels areusually installed in an aircraft: one for thepilot and the other for the copilot. The twopanels are identical and provide the pilot andcopilot with identical facilities. The operatingcontrols and their functions are listed in thechart below.

Control

RECEIVERS, re-ceiver selectionswitches.

Function

Selects receiver, the output ofwhich will be applied to headsets.

l—In the up position, the switchconnects the output of the f mliaison set to the headset-micro-phone associated with the INTsignal distribution panel. In thedown position, it disconnects thefm liaison set receiver outputfrom the headset-microphone.(See note 1.)

2-In the up position, the switchconnects the output of a secondreceiver to the headset-micro-phone associated with the INTsignal distribution panel. In thedown position, it disconnects thesecond rcceiver from the head-set-microphone. (See note 1.)

3-in the up position, the switchconnects the output of a thirdreceiver to the headset-micro-phone associated with the INTsignal distribution panel. In thedown position, it disconnects thethird receiver from the headsetmicrophone. (See note 1.)

MB-In the up position, the switchconnects the audio output of themarker beacon receiver to theheadset-microphone associatedwith the INT signal distributionpanel. In the down position, itdisconnects the marker beaconreceiver from the headset-micro-phones.

NAV—In the up position, theswitch connects the audio outputof the navigational receiver o rautomatic direction finder re-ceiver to the headset-microphone

CONTROLS

Figure 11. INT Signal distribution panel, front view

Control

TRANS selectorswitch. (Seenote 1.)

Headset VOLcontrol.

associated with the INT signaldistribution panel. (See note 2.)

Selects fm liaison set, receiver-transmitter number 2, receiver-transmitter number 3, orinterphone facility.

INT position—Connects the INTsignal distribution panels to-gether for interphone operation.At the same time, the operatorwill hear his own transmissionas a sidetone signal in his head-set-microphone. The other crew-member will hear the interphonemessage regardless of the posi-tion of his INT signal distri-bution panel TRANS selectorswitch.

1, 2, and 3 positions—Selects thereceiver-transmitter to be usedto receive or transmit, regardlessof the positions of the RE-CEIVERS 1, 2, or 3 switches.

Adjusts the volume level of theaudio applied to the headset-microphone associated with theINT signal distribution panel.(See note 2.)

Notes .

1. The number selections of the TRANS selector switch corre-spond to the numbers of the RECEIVERS switchen. For thismanual, it is assumed that the function of each position of theTRANS switch is as indicated below.

TRANS selector switch:Position 1 : FM transmitterPosition 2 : Transmitter number 2Position 3 : Transmitter number 3

2. The receiver VOL control has no effect on the audio level o fthe navigational receivers. Their level is adjusted by the controlpanel associated with that equipment.

1 9

Figure 12. FM control panel, front view.

18. FM Control Panel(fig. 12)

The FM control panel provides for remotecontrol of the fm liaison set. The followingchart lists the controls on the FM control paneland their functions.

Control

Power ON-OFFswitch.

REM-LOCALswitch.

1/10 and wholemegacycleFREQ selectorswitches.

Receiver VOLcontrol.

2 0

Function

In the ON position, applies powerto the fm receiver-transmitter.In the OFF position, removespower from the fm receiver-transmitter.

Must always be in LOCAL position.Used only when two or more FMcontrol panels are used.

Selects the receiving and transmit-ting frequency of the fm re-ceiver-transmitter.

Outside knurled ring ( whole-mega-cycle FREQ selector), selectsfirst two numbers of receiverand transmitter operating fre-quencies.

Inside knob (l/l0-megacycle FREQselector), selects third numberof transmitter and receiver op-erating frequencies.

Provides volume control for thefm receiver-transmitter receiveraudio. Turn clockwise to increasethe audio output.

19. Power Switches and ControlsThe following controls, although not part of

the fm liaison set, are directly related to theoperation of the equipment. These controls arenot supplied as part of the fm liaison set butare supplied as part of the aircraft in whichtn. set is installed:

Control

Master power on-off switch.

FM push-pull cir-cuit breaker.

Microphoneswitch.

Lights control . . . .

Squelch switch-..

Homing switch-..

Function

When actuated (in), applies powerto the dynamotor and INT sig-nal distribution panels. Alsomakes power available for useby the fm liaison set.

When in the on position, power ismade available to the fm push-pull circuit breaker.

Normally a two-position switch.In one position, it energizes thetransmitter; in the other posi-tion, it deenergizes the trans-mitter,

Varies the brilliance of the panellamps on the control panels.

Permits squelching of the fm liai-son set.

Activates the homing circuits inthe fm receiver-transmitter andpermits homing operation; deac-tivates the transmitting facility.

• Installed as part of the airframe only when Switch Assembly

SA-474/AR is not included in the aircraft.

Section Il.

20. Types of Operation

OPERATING INSTRUCTIONS

b. Starting.

a. The fm liaison set is operated remotelyfrom the aircraft cockpit through the use ofthe FM control panel and the INT signal dis-tribution panel. Depending on the setting ofthe various controls, the fm liaison set can beoperated as an fm receiver-transmitter, an fmhoming receiver, or as an interphone system.

b. The RECEIVERS 2, 3, NAV, and MBswitches on the INT signal distribution panelare used to connect additional receiversthrough the INT signal distribution panels.For the application of these switches, refer tothe applicable aircraft electronic communica-tion configuration manual that covers the otherfacilities that are used with the AN/ARC-44.

c. To operate the equipment for any partic-ular type of operation, perform the following:

(1) Starting procedure (para 21).(2) Procedure for interphone operation

(para 22).(3) Procedure for fm liaison set operation

(para 23).(4) Procedure for fm homing (para 37b).(5) Stopping procedure (para 23c).

21. Starting Procedurea. Preliminary. Set the various controls as

follows :

Control Position

Master power on-off switch . . . . . . . . . . off .Fm push-pull circuit breakerª . . . . . . off .Squelch switchb . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . off.Homing switchb . . . . . . . . . . . . . . . . . . . . . Communication

position.RECEIVERS switches (fig. 11) . . . . All in down (off)

positions.Headset and receiver VOL controls Full counter-

(figs. 11 and 12). clockwise.TRANS selector switch (fig. 11) . . . . INT.Power ON-OFF switch (fig. 12) . . . . OFF.REM-LOCAL switch (fig. 12) . . . . . . . . LOCAL.1/10 and whole megacycle FREQ Rotate for

selector switches (fig. 12). desiredfrequency.

HOME, SQUEL, and SPARE All switches inswitches c (fig. 13). the off (down)

position.

a. Part of aircraft power circuitry.b. Used only when Switch Assembly SA-4’74/AR is not installed

in the aircraft.c Normally installed in aircraft when Antenna Group AN/

ARA-31 is used with the fm liaison set.

(1)

(2)

(3)

(4)

(5)

Place the aircraft master power on-off switch to its on position.Actuate the aircraft fm push-pull cir-cuit breaker.Set the squelch switch to off (down)position.Set the homing switch to the com-munication position.Allow the INT signal distributionpanel to warm up for approximately3 minutes.

(6) Follow the procedures in paragraphs22 and 23 for the desired type ofoperation.

22. Interphone Operationa. From either the pilot or copilot posi-

tions, press the microphone switch.

b. Speak into the microphone; sidetone willbe heard in the pilot and copilot headsets.

c. Adjust the INT signal distribution panelheadset VOL controls for comfortable audioin the headset.

Note. It is not necessary for both INT signal distri-bution panels to be at INT. Sidetone and interphonecommunication will be heard at the other positionwhenever the operator place his switch in the INTposition.

23. Fm Liaison Set OperationNote. Refer to paragraph 21b for starting procedure.

a. Reception.

(1)

(2)

(3)

On the operator’s INT signal distri-bution panel (fig. 11), place the RE-CEIVERS 1 switch at up.Turn the VOL control on the INTsignal distribution panel fully clock-wise for maximum volume.On the FM control panel (fig. 12),place the power switch at ON. Allowapproximately 2 minutes for warmup.Cycling (automatic frequency selec-tion ) may take place in the fm re-ceiver-transmitter. This will beindicated by a 400-cycle-per-secondsignal heard in the headsets. Thetone lasts approximately 6 seconds,

21

(4)

(5)

(6)

(7)

(8)

Be sure that the REM-LOCAL switchis at LOCAL.

Note. In a two FM control panel installa-tion, the FM control panel not selected forLOCAL operation will automatically switchto REM when the power ON-OFF switch isset to ON. The FM control panel in theREM position will lose frequency control andfrequency selection.Select the required frequency withthe 1/10 and whole megacycle FREQselector switches. Set the whole-megacycle FREQ selector switch(outer perimeter knob of the FREQcontrol) until the number appearingcorresponds to the whole-megacyclenumber of the operating frequency.Set the inner 1/10 megacycle FREQselector switch to the exact 1/10 meg-acycle.Turn the receiver VOL control on theFM control panel for maximum vol-ume, and reduce the volume to asuitable listening level, if necessary,with the headset VOL control on theINT signal distribution panel (fig.11).To eliminate background noise whenno signal is being received, place thesquelch switch (fig. 13) to the on(squelched) position.If the incoming signal is too weak,the reception can be improved byplacing the squelch switch to the un-squelched (off) position to enable thereception of weak signals. Normally,the switch is on.

b. Transmission.(1)

(2)

(3)

(4)

(5)

Operate the fm liaison set for recep-tion as indicated in a above.Check to be sure that the fm homingswitch, if installed, is in the com-munication position.

Note. Refer to paragraph 37b for homingoperation.On the INT signal distribution panel(fig. 11) of the operator desiring totransmit, turn the TRANS selectorswitch so that 1 appears in the win-dow just above the switch.

Note. With the TRANS selector switch inthe 1 position, interphone operation is over-ridden during transmission.Transmit by depressing the micro-phone switch to the communicationposition. Keep it depressed whilespeaking.Release the microphone switch to re-ceive the return transmission.

c. Stopping.(1) Set the power switch on the FM con-

trol panel (fig. 12) to OFF.(2) On the INT signal distribution panel

(fig. 11), place the RECEIVERS 1switch to its down (off) position andthe TRANS selector switch in theINT position.

(3) If the entire communication facilityis to be shut down completely, proceedas follows:

(a) Set the master power on-off switchto its off position.

(b) Pul l t he fm push-pu l l c i r cu i tbreaker out.

22

CHAPTER 3

PREFLIGHT (DAILY) INSPECTION

24. Generala. The operator’s inspections listed in para-

graph 25 and 26 below supplement the inspec-tion procedures in the pilot’s preflight check-list. The operator’s inspections consist ofchecking the fm liaison set for flight prepared-ness by performing a visual inspection (para25b) to discover defects and an operationalcheck (para 26) to verify serviceability. Theinspections listed should be accomplished priorto the first flight of the day, as called for bylocal standard operating procedure, or as indi-cated in the flight manual covering the air-craft in which this equipment is installed.

b. The pilot or copilot should report anymalfunction or failures noted in flight and anydiscrepancy noted in the preflight inspectionon DD Form 781–2.

25. Inspections for l ll Flightsa. Exterior Inspection. While making the

exterior walkaround inspection of the aircraft,check the communication antenna and the fmhoming antennas (if installed) for crackedinsulators, broken elements, loose mounting,damaged insulation, and frayed cabling.

b. Interior Inspection. The interior inspec-tion indicated below is to be performed on adaily basis and in accordance with the “OnEntering the Airplane” checklist contained inthe applicable Pilot’s Flight Handbook. Thisinspection ((1) through (4) below) is an ex-tension of the tests given in the handbook.

(1)

(2)

(3)

(4)

Visually inspect the fm liaison set forcompleteness, evidence of damage,and security of mounting and safetywiring.Check all control panels for loose orbinding knobs.Check shock mounts for cracks, cor-rosion, loose attaching bolts or rivets,deterioration of rubber, and loose ormissing bonding.Check operational controls for looseor missing knobs and for proper oper-ation. Insure that all controls and

switches are in the positions indicatedin paragraph 21a.

26. Preflight Inspection, Power Ona. General. The following preflight tests

should be made during engine warmup as anextension of the “Ground Tests” in the appli-cable Pilot’s Flight Handbook. The pilot or co-pilot should perform the tests (b through dbelow) in the order given. While performingthese tests, check for the following:

(1)

(2)

(3)(4)(5)

(6)(7)

Clarity of sidetine (c(27) and d (6 )below) .Clarity of received signal (c(2) andd(6) below).Ease of tuning (d(3) and (6) below).Accuracy of tuning (d(3) and (6)).Operation of controls, smooth with noerratic indication of binding ( b , cand d below).Clarity of transmission (d(3) below).Performance of homing facility, ifinstalled (d(9) below).

b. Preliminary.(1) Place the aircraft master power on-

off switch to its on position.(2) Actuate the aircraft fm push-pull cir-

cuit breaker.c. Interphone.

(1)

(2)

(3)

(4)

Place the TRANS selector switch(fig. 11) on both INT signal distribu-tion panels to the INT position.Press the microphone switch to theinterphone position and speak intothe microphone. Sidetone should beheard in the headset-microphone. Thetest communication should also beheard at the other position.Adjust the volume control of eachINT signal distribution panel to acomfortable level.Repeat the procedure in (2) abovefrom the copilot’s position. The testcommunication should now be heardat the pilot’s position.

d. Fm Liaison Set.(1) On the FM control panel, (fig. 12),

23

(2)

(3)

(4)

(5)

(6)

place the power ON-OFF switch tothe ON position.On the pilot’s INT signal distributionpanel, (fig. 11), place the RE-CEIVERS 1 switch to the on (up)position.Turn the FM control panel frequencyselector switches to a known fm sta-tion transmission.

Note. A 400-cycle tone will be heard inthe headsets when changing channels.On the INT signal distribution panel,turn the headset VOL control formaximum volume and use the receiverVOL control on the FM control panelto regulate the audio output. Read-just the INT signal distribution panelheadset VOL control, if necessary.On the pilot’s INT signal distribu-tion panel, place the RECEIVERS 1switch in the off (down) position, andplace the TRANS selector switch inthe 1 position.On the FM control panel, tune to alocal fm station, and establish com-munication. While communicatingwith the station, check operation ofthe squelch circuit by operating thesquelch switch back and forth. Whenno signal is being received and thesquelch switch is placed in the onposition, background noise will not

(7)

(8)

(9)

be heard; in the off position, back-ground noise is heard.Repeat the instruction in (6) abovefor several different frequencies. ifpossible.Repeat (2) through (6) above fromthe copilot’s position.

Note. If Antenna Group AN/ARA–31 isnot installed, omit (9) (a) through (c)below.To test the fm homing facility, pro-ceed as follows:

(a) Place the homing switch (para 19)at the homing position.

(b) A steady tone, U (..-) or D (-..),should be heard in the headset-microphones, depending on the lo-cation of the aircraft with respectto the transmitting station. (Re-fer to figure 15. )

(c) Return the homing switch ( (a)above ) to the off position.

(10) To shut down the fm liaison set, pro-ceed as follows:

(a) Place the FM control panel powerswitch to its OFF position.

(b) Place the INT signal distributionpanel TRANS selector switch tothe INT position.

(c) Pull the aircraft fm push-pull cir-cuit breaker out.

(d) Set the aircraft master power on-off switch to its off position.

24

CHAPTER 4

ORGANIZATIONAL MAINTENANCE

27. Scope of Organizational MaintenanceOrganizational maintenance of the fm liaison

set, as performed by the organizational repair-man or crew chief, consists of preventivemaintenance, including mechanical and electri-cal checks and cleaning. Report all deficiencies,malfunctions, or abnormal conditions on DDForm 781-2 (para 2c). For the interval andmore specific details for performing preventivemaintenance on this equipment, refer to theapplicable aircraft organizational maintenancemanual. Paragraphs 29 through 32 providegeneral organizational maintenance proceduresthat should be used when performing preven-tive maintenance on this equipment. Removaland replacement instructions are provided inparagraph 33; adjustments to be made whenthe equipment is reinstalled in the aircraftafter repairs or after the scheduled periodicpullout checks are given in paragraph 34.

28. Tools, Materials, and Test EquipmentRequired

The only tools, materials and test equipmentrequired for performing organizational main-tenance are as follows:

a. Mult imete r AN/URM-105 (TM 11-6625–203-12).

b. Tool Equipment TE–41.c. Cleaning Compound, Federal stock No.

7930–395-9542.

29. Preventive Maintenance Techniquesa. Use No. 000 sandpaper to remove rust

and corrosion.b. Use a clean, dry, lint-free cloth or a dry

brush for cleaning. If necessary, wipe anyparts, including electrical contacts by using acloth moistened with cleaning compound; thenwipe the cleaned parts dry with a clean drycloth.

Caution: Cleaning compound is flammableand its fumes are toxic. Do not use near aflame; provide adequate ventilation.

30. Preventive Maintenance Instructionsa. Check for completeness and general con-

dition of the fm receiver-transmitter, FMcontrol panel, INT signal distribution panel,dynamotor, communication antenna, andmountings. Make sure no knobs, screws, orlamps are missing. Check both fuses in thedynamotor to see that they are 0.5 ampere andin good condition.

b. Remove dirt and moisture from thecases, component panels, antenna, mountings,air intake screen, wiring, cables, and connec-tors. Disconnect the plugs and jacks, cleantheir contacts, and reconnect them.

c. Inspect all metal surfaces on the cases,component panels, mountings, antenna, andconnectors for rust and corrosion. Remove therust and corrosion by using fine sandpaper.

d. Inspect the wiring, cords, cables, andshock mounts for cuts, kinks, breaks, fraying,and signs of excessive strain. Check all bond-ing straps and safety wire to assure that eachcomponent is properly grounded and properlysafety wired.

e. Check all controls and accessible items(switches, knobs, connectors, pilot lights, fuse-holders, screws, nuts, and bolts) to make surethat they are properly tightened. Tighten anyitem that is loose.

f. Inspect all controls for easy operation.g. Check for normal operation of the fm

liaison set (para 31) from the pilot positionand the copilot position.

31. Equipment Performance Checklista. General. The equipment performance

checklist is used to systematically check theperformance of the fm liaison set. All correc-tive measures which the organizational repair-man can perform are given in the Correctivemeasures column. When using the checklist toverify serviceability of the equipment, start atthe beginning and follow each step in sequence.Successful completion of the checklist indicatesthat the equipment is operating in a satisfac-tory manner. When using the performancechecklist, first determine from DD Form 781–2the cause or symptom of failure, Get firsthandinformation from the pilot or copilot on how

25

the equipment was operating just before fail-ure. Perform the preparatory proceduresgiven in c below before beginning. If troubleis found and the corrective measures indicateddo not correct the cause, troubleshooting is re-quired by a higher echelon. On DD Form 781-2note the symptoms, how the equipment per-formed, and what corrective measures weretaken.

1). Auxiliary Power. Before attempting tooperate the fm liaison set, be sure that an ex-ternal power supply is connected to the air-—

PREPARATORY

—Step—

1

2

3

4

5

6

7

8

9

—

Unit

Both FM controlpanels (fig. 12).Note. If aircraft

uses one FM controlpanel apply subse-quent procedure ap-proriate to one FMcontrol panel.

Both INT signaldistributionpanels (fig. 11).

Switch panel (fig.13) or equiv-alent.

craft. The receptacle for connecting the exter-nal power supply is normally on the left sideof the fuselage; refer to the applicable aircrafttechnical manual for exact location, When theexternal power source is connected to the air-craft, the aircraft battery is isolated from theaircraft electrical system.

Warning: When an external power supplyis connected, the aircraft electrical system isenergized regardless of the position of theaircraft battery switch.

c. Equipment Performance Checklist.

Set power switch to OFF.

Rotate receiver VOL con-trol fully counterclock-wise.

Set REM-LOCAL switchto LOCAL position onone panel.Note. If l ircraft uses only one

FM control panel, leave REM-LOCAL switch in LOCAL throughout checklist and ignorefurther reference to it.Rotate frequency selector

switches until desiredfrequency appears inFREQ window.

Set all RECEIVERSswitches to their off(down) positions.

Rotate TRANS selectorswitch to INT.

Rotate headset VOL con-trol fully counterclock-wise.

Set FM HOME switch orequivalent to off posi-tion and, FM SQUELCHswitch or equivalent tooff position.Note. If Aircraft does not con.

tain the switch panel, squelchswitch squelch control) for theFM laision set is mounted sep-arately. Refer to applicable con-figuration manua1 for itslocation

Corrective measures

26

PERFoRMANcE

Step—

10

11

12

13

14

Unit

Aircraft mainpower switchand appropriatecircuit break-ers. Refer to babove for appli-cation of auxil-iary power.

Either INT signaldistributionpanel (fig. 11).(Select eitheroperating posi-tion in the air-craft. )

Other INT signaldistributionpanel (fig. 11)(other operat-ing position inthe aircraft).

Turn on main powerswitch and appropriatecircuit breakers. Allowsufficient warmup time.

Press microphone switchfrom selected operatingposition and speak intomicrophone. Listen onthis position’s headsetand adjust headset VOLcontrol to comfortableaudio level.

Press microphone switchfrom this operating po-sition and speak intomicrophone. Listen onthis position’s headsetand adjust headset VOLcontrol to comfortableaudio level.

From either operating po-sition, press microphoneswitch and speak intomicrophone while listen-ing to headset in otheroperating position.

From other operating po-sition, repeat step 13above:

Normal indication

Characters, numerals,and panel lights oncontrol panel and dis-tribution panels glow.

Dynamotor rotates.

Fan motor in fm re-ceiver-transmitteroperates.

Sidetone heard in head-set.

Sidetone heard in head-set.

Audio heard in headset.

Same as step 13.

Corrective measures

Replace lamps.

Check to see if aircraftpower is available at mainpower switch and circuitbreakers.

Check for 27.5 volts dc atdynamotor terminals H, L,and J on P101 (fig. 6). Ifno voltage is present, checkwiring leading to termi-nals. If voltage is present,replace dynamotor (para33i and j).

Check 27-volt ac supply fromdynamotor at terminals Vand X on P815 (fig. 3).Note. Fan in fm receiver-trans-

mitter should exhaust air from rearof unit for proper air circulation.If fan draws in air at rear ofunit, replace fm receiver-transmit-ter (para 33c and d).

Check fuse F101 in dy -namotor and replace ifdefective (fig. 6). Checkheadset-microphone by sub-stitution. Replace INT sig-nal distribution panel (para336g and h). Check overallcabling between headset-microphone and INT signaldistribution panel. Checkmicrophone switch and as-sociated circuitry.

Check headset-microphone bysubstitution. Replace INTsignal distribution panel(para 33g and h). Checkoverall cabling betweenheadset-microphone andINT signal distributionpanel. Check microphoneswitch and associated cir-cuitry.

First replace one INT signaldistribution panel (para33g and h). If audio is notheard in headset, then re-place other INT signaldistribution panel. Checkcabling between distribu-tion panels.

Same as step 13.

27

PERFoRMANcE

15

16

17

18

19

Unit

Both INT signaldistributionpanels (fig. 11).

Either FM controlpanel (fig. 12)( select eitheroperating posi-tion correspond-ing to the FMcontrol panels).

Other FM controlpanel (fig. 12).

Note. If aircraft hasonly one FM controlpanel installed, pro-ceed to step 19 below.

Switch panel (fig.13).

Note. If l ircraft doesnot have the homingfacility Installed. pro-ceed to step 21 below.

Rotate TRANS selectorswitch to position 1 andRECEIVERS 1 switchto on (up) position.Note. It is assumed that fm

receiver-transmitter is wired to1 positions of INT signal distri-bution panels ; however, checkaircraft frequency card to besure.

Set REM-LOCAL switchto LOCAL. Rotate fre-quency selector switchesto frequency of localfm ground station. SetON-OFF switch to ONposition. Allow sufficientwarmup time. Adjustreceiver VOL control tocomfortable audio level.

From the operating posi-tion selected in step 16above, press the micro-phone switch, speak intothe microphone and es-tablish fm communica-tions.

Same as step 16 above.

Set homing switch to(up) position, Select fmstation, preferably onewith a known relativebearing.

Characters, numerals,and panel lights glow.

400-cps cycling toneheard in headsetwhile fm receiver-transmitter is cyclingto frequency selected:

Noise or fm communi-cations heard inheadset.

Reliable fm communi-cations established.

Same as step 16 above.

Keyer motor starts run-ning. A coded D (- . .)or U (.. -) 400-cpssignal or a continu-ous 400-cps signal isheard in headset, de-

Corrective measures

Check cable connection toFM control panel, Replacedefective lamps.

If 400-cps cycling tone lastslonger than 10 seconds,turn ON-OFF switch toOFF. Check cable connec-tions to fm receiver-trans-mitter and FM controlpanel. Replace fm receiver-transmitter (para 33c andd).

Check cable connections be-tween INT signal distribu-tion panel, FM controlpanel, and fm receiver-transmitter. Replace FMcontrol panel (para 33eand f). Replace fm receiver-transmitter (para 33c andd). Check overall wiringbetween these units.

No transmission: Check fuseF102 in dynamotor and re-place if defective. If sec-ond fuse blows, replace fmreceiver-transmitter (para33c and d). Check cableconnections for fm controlpanel, INT signal distri-bution panel, and fm re-ceiver-transmitter. ReplaceFM control panel (para 33eand f). Check overall wir-ing between these units.

No reception: same as step16 above.

Check cable connections toFM control panel. ReplaceFM control panel (para 33eand f). Check overall wir-ing to FM control panel.

If no 400-cps tone signal isheard, replace fm receiver-transmitter (para 33c andd). Replace the switchassembly. If no homingsignal is heard, check for

2 8

PERFoRMANcE

—

sToP

—

Step—

20

—

21

22

—

Unit

Both FM controlpanels (fig. 12).

Aircraft mainpower switchand appropriatecircuit breakers.

Set homing switch to offposition. Set squelch toon position and then tooff position.

Set power ON-OFF switchto OFF position.

Turn off main powerswitch and appropriatecircuit breakers.

Normal indication

pending on aircraftheading.

Considerable decreasein receiver noisewhen squelch is setto on position.Abrupt increase inreceiver noise whenset to off position.

Character, numerals,and panel lights ceaseto glow.

Dynamotor stops oper-ating and INT signaldistribution panelsare turned off.(Fan motor stops.)

Corrective measures

fm communications by set-ting homing switch to offposition. If fm communi-cations is present, checkhoming antenna system;replace Keyer KY-149/AR.

Check FM SQUEL switchand switch assembly andconnections to fm receiver-transmitter. Check squelchadjustment on fm receiver-transmitter (para 34).

Check power ON-OFF switchand if defective, replaceFM control panel (para33e and f).

Check for defective powerswitch and circuit breakers.

32. Maintenance of Dynamotor holder and observe the condition of

a. General Organizational maintenance ofthe dynamotor consists of inspection, replace-ment of fuses, brushes, brush caps, and re-placement of the dynamotor when it becomesdefective. Instructions for the inspection andreplacement of dynamotor brushes and brushcaps are given in a below. Instructions for theremoval and replacement of the dynamotor aregiven in paragraphs 33i and j.

b. Inspection, Removal, and Replacementof Brushes and Brush Caps (fig. 6).

Note. When removing the dynamotor brushes, ob-serve the markings and relative position of each brushwith respect to its holder. Each brush is marked withits polarity on one side and with a brush wear line onthe other. Replace each brush in the same positionand in the same brush holder from which it was re-moved. The polarity mark should always face up whenthe brush is in its holder. Proper replacement ofbrushes results in smoother operation of the dynamotor,

(1)

(2)

Unscrew the brush cap from its re-spective holder assembly and observethe brush spring tension. If the brushspring tension is weak, replace thebrush assembly with a new one.Remove the brush assembly from its

33.

(3)

the brush. If the brush is chipped,broken, or worn to brush wear line,replace it with a new brush assembly.Before replacing the brush caps afterinspection and replacement of brushes,note the condition of each cap. Re-place the cap with a new one if it isnicked, broken, or damaged.

Removal and Replacement of Fmliaison Set

a. General. This paragraph contains gen-eral removal and replacement procedures of allthe components of the fm liaison set authorizedto be replaced in the aircraft at the organiza-tional maintenance level. When it has beendetermined by troubleshooting that a majorcomponent is malfunctioning or inoperative,replace it with a serviceable unit. Since instal-lations of this equipment may vary in differentaircraft, it may be necessary to refer to theappropriate aircraft or configuration technicalmanuals to accomplish removal and replace-ment of these components.

b. Safety Wiring. When the components

29

are reinstalled, be sure that holddown bolts,mounting nuts, and appropriate plugs and con-nectors are properly safety wired.

c. Removal of Fm Receiver- Transmitter(fig. 3).

(1)

(2)

(3)

(4)

Disconnect antenna cable from plugP803A on the front of the fm re-ceiver-transmitter.Cut and remove the safety wire fromthe mounting screws.Unscrew both mounting screws fromtheir mounting blocks at the front ofthe fm receiver-transmitter; turn bothscrews simultaneously and at thesame rate.Slide the fm receiver-transmitter for-ward and upward and remove it fromthe receiver-transmitter mounting.

d. Replacement of Fm Receiver- Transmitter(fig. 3).

(1)

(2)

(3)

(4)

Carefully place the fm receiver-trans-mitter on the receiver-transmittermounting.Slide the fm receiver-transmitter tothe rear of the shock mount until theguide pins mate and plug P815 andreceptacle J815 properly engage.Screw in the mounting screws andsecure the fm receiver-transmitter tothe shock mount. Safety-wire the twomounting screws.Connect the antenna cable to plugP803A on the front of the fm re-ceiver-transmitter.

e. Removal of FM Control Panel (fig. 5).(1)

(2)

(3)

(4)

Unscrew the four Dzus fasteners thatmount the FM control panel.Withdraw the FM control panel farenough to reach the spring lock fas-teners that secure the panel connectorto the rear of the panel.Unscrew the spring lock fastenersand disconnect the panel connectorfrom receptacle J201.Remove the FM control panel.

f. Replacement of FM Control Panel (fig. 4).(1)

(2)

30

Connect the panel connector to re-ceptacle J201 and tighten the springlock fasteners that secure the con-nector to the rear of the FM controlpanel.Set the FM control panel in place and

tighten the four Dzus fasteners thatmount the panel.

g. Removal of INT Signal DistributionPanels (fig. 5). Each panel is removed in thesame manner as follows:

(1)

(2)

(3)

(4)

Unscrew the four Dzus fasteners thatmount the INT signal distributionpanel.Withdraw the INT signal distributionpanel far enough to reach the springlock fasteners that secure the panelconnector to the rear of the INTsignal distribution panel.Unscrew the spring lock fasteners anddisconnect the panel connector fromreceptacle J301.Remove the INT signal distributionpanel.

h. Replacement of INT Signal DistributionPanel (fig. 5).

(1)

(2)

Connect the panel connector to recep-tacle J301 and tighten the spring lockfasteners that secure the connector tothe rear of the INT signal distributionpanel.Set the INT signal distribution panelin place and tighten the four Dzusfasteners that mount the INT signaldistribution panel.

i. Removal of Dynamotor (fig. 6 and 7).(1)

(2)(3)

(4)

Cut and remove the safety wire fromthe mounting screws.Unscrew the mounting screws.Slide the dynamotor forward to dis-connect the connectors and guidepins at the rear of the dynamotormounting.Slide the dynamotor forward and outof the guide rail to remove it fromthe mounting.

j. Replacement of Dynamotor (fig. 6 and 7).(1) Carefully place the dynamotor on its

(2)

(3)

k. Removal of Communication Antenna(fig. 8).

mount by sliding it to the rear untilthe connectors and guide pins prop-erly engage.Screw in the mounting screws to se-cure the dynamotor to the mounting,Safety-wire the mounting screws toprevent them from loosening.

(1) Disconnect the coaxial connector fromthe base.

(2) On the base, loosen the ¼-inch Allensetscrew and the 1-inch whip tighten-ing nut (5/8-inch on A models).

(3) Unscrew and remove the communica-tion whip.

(4) Remove the six screws that hold thebase and gasket to the aircraft.

(5) Remove the base and the gasket.l. Replacement of Communication Antenna

(fig. 8).(1) Replace the gasket and base and se-

cure them to the aircraft with thesix screws.

(2) Screw the whip in the base andtighten the ¼-inch Allen setscrew andthe l-inch tightening nut (5/8-inch onA models).

(3) Connect the coaxial connector to thebase.

34. FM Receiver-Transmitter SquelchAdjustment

The SQUELCH control for the fm receiver-transmitter is located above the handle on theleft side of the front panel (fig. 3). The con-trol is behind a sliding panel that can bemanually raised by moving the slide buttonadjacent to the SQUELCH control . TheSQUELCH control is adjusted as follows:

a. Place the fm receiver-transmitter in thereceive condition (para 23) with no signalinput by disconnecting the antenna cable fromplug P803A.

b. Set the squelch switch on the switchpanel (fig. 13) to its off position.

Note. When the squelch switch is in its on position,the receiver squelch circuits are used. When it is in theoff position, an external bias voltage is applied to thereceiver, disabling the receiver internal squelch circuits.

c. Adjust the background noise in the head-sets to a comfortable level; use the headsetVOL control on the INT signal distributionpanel (fig. 11) or the receiver VOL control onthe FM control panel (fig. 12).

d. Rotate SQUELCH control (fig. 3) onthe fm receiver-transmitter to its maximumcounterclockwise position.

e. Set the squelch switch on the switchpanel (fig. 13) to its on position.

f. Rotate the SQUELCH control clockwiseto the position where the background noise justcuts out. Do not rotate the control beyond thispoint.

g. Check the squelch setting on severalother frequencies. If all frequencies selectedare not fully squelched, turn the SQUELCHcontrol slightly more clockwise.

h. Remove power from the fm liaison setand reconnect the antenna cable to plug P803A.

31

CHAPTER 5

AUXILIARY EQUIPMENT

35. Introduction homing and for squelch control of the fm re-

a. Antenna Group AN/ARA-31 and Switch ceiver-transmitter.

Assembly SA-474/AR are used as auxiliary b. The description and operation of SA-equipment to extend the operational use of the 474/AR and Antenna Group AN/ARA-3l arefm liaison set. This equipment respectively covered in paragraphs 36 and 37. Removal andprovides the fm liaison set with homing op- replacement instructions for Switch Assemblyeration and remote switching operation for SA–474/AR are also included in paragraph 36c.

Figure 13. Switch Assembly SA-464/AR.

32

c. Complete description, operation, and or-ganizational maintenance for Antenna GroupAN/ARA-31 are covered in a separate Department of the Army publication.

36. Switch Assembly SA-474/AR(fig. 13)

a. Description. The switch panel is a sep-arately housed unit containing five front panelswitches. All five switches are wired to re-ceptacle J1801 on the rear of the switch panel.All switch functions are indicated on the frontpanel. Only two of these switches function aspart of the fm liaison set; the other three aredesignated as spares. Two panel lights edge-light the front panel The switch panel is flushmounted by means of four Dzus fasteners lo-cated on the sides of the panel mounting plate.Two panel mounting screws secure the plasticpanel to the panel mounting plate. All externalconnections are made through receptacle J1801on the rear of the switch panel.

b. Control Function. The following chartlists the switch panel controls and indicatestheir functions.

Control Function

FM HOMEtoggle switch.

FM SQUELtoggle switch.

In the on position, this switch ener-gizes the homing circuits, discon-nects the communication antenna,connects the homing antennasthrough Keyer KY-149(•)/AR(para 37a(2) to the fm receiver-transmitter input, and disablesthe microphone switch. In the offposition, homing operation is dis-abled, and the fm liaison setreturns to normal receiving oper-ation.

In the off position, receiver outputis unsquelched. In the on position,squelch circuits operate.

Not used with the fm liaison set,

tronic equipment installed in the

Note. Refer to paragraph 37b for homing operation.c. Replacement and Removal of Switch

Panel (fig. 13).(1) Removal.

(a) Unscrew the four Dzus fastenersthat mount the switch panel.

(b) Withdraw the switch panel farenough to reach the spring lock

(c)

(d)

fasteners that secure the panel con-nector to the rear of the switchpanel.Unscrew the spring lock fastenersand disconnect panel connectorP1801 from receptacle J1801.Remove the switch panel,

(2) Replacement.(a)

(b)

Connect panel connector P1801 toreceptacle J1801 and tighten thespring lock fasteners that securethe panel connector to the rearswitch panel.Set the switch panel in place andtighten the four Dzus fasteners thatmount the switch panel.

37. Antenna Group AN/ARA41a. Description (fig. 14).

(1)

(2)

(3)

Antenna Group AN/ARA-31 consistsof Keyer KY-149(*)/AR, MountingMT-1620/AR, two Networks, Imped-ance Matching CU-459/AR, and fourAntenna Elements AT-624(*)/AR.T w o A n t e n n a E l e m e n t s A T -624 (*) /AR and one Network, Im-pedance Matching CU-459/AR makeup a homing antenna. There are twoidentical homing antennas: one forthe left side of the aircraft, and onefor the right side.Keyer KY-149(•)/AR is a separatelyhoused unit mounted on MountingMT–1620/AR which is a flat mount-ing base. The keyer is enclosed by asliding cover which is held in place bya single spring lock fastener on therear of the cover. The front panel ofthe keyer contains four coaxial con-nectors and a two-pin connector for a28-volt power input. The keyer issecured to the mounting by twomounting screws located at the f rentof the unit.Network, Impedance Matching CU-459/AR has a bullet-shaped, blacknylon shell. Two antenna connectorsare mounted on the outer surface ofthe bullet, one on each side. All thecomponents within the bullet housingare permanently sealed to preventchanges in impedance characteristics

33

Figure 14. Antenna Group AN/ARA–31.

which might be caused by a shiftingof the components’ positions.

b. Operation. Place the fm liaison set inoperation as instructed in paragraphs 21through

(1)

(2)

(3)

23.Set the FM HOME toggle switch onthe switch panel to its on position(fig. 13).Rotate the frequency selector switcheson the FM control panel to the de-sired operating frequency. The codedD and U signals or steady 400-cpson-course tone should be present inthe operator’s’ headset-microphone (orboth operators’ headset-microphonesin a two-position installation).Three types of signals that are heardwhen using the homing facility aregiven below. Each signal has a spe-cific meaning to the pilot. Figure 15gives an illustrative example of hom-ing signal use.

Signal Meaning

A keyed 400-cps The transmitting station to whichtone with the I am tuned is on the left (port-code character side ) of the course that I amD — “dah-dit- heading. I must turn to the leftdit" predomi- until my headset-microphone sig-nant. nal changes to a steady 400-cps

tone.

A keyed 400-cps The transmitting station to whichtone with the I am tuned is on the right (star-code character board side) of the course that IU _ "dit-dit- am heading. I must turn to thedab” predomi- right until my headset-phonenant. signal changes to a steady 400-

cps tone.

A steady 400-cps I am heading directly toward thetonea. transmitting station to which I

am tuned.

* it is possible that, when a steady 400-cps tone is heard, theaircraft is heading directly l way from the station. By flying tothe right or left of the on-course heading, the l rror may be cor-rected by following the directions for reception of D and U signals.

(4) Turn off the equipment as instructedin the stopping procedure (para 23c).

34

Figure 15. Identifying homing signals.

35

CHAPTER 6

DEMOLITION OF MATERIEL TO PREVENT ENEMY USE

38. Authority for DemolitionDemolition of the equipment will be accom-

plished only upon the order of the commander.The destruction procedures outlined in para-graph 39 will be used to prevent further useof the equipment.

39. Methods of DestructionUse any of the following methods to destroy

the equipment.a. Smash. Smash the controls, tubes, coils,

switches, capacitors, and transformers; usesledges, axes, handaxes, hammers, or crowbars.

b. Cut. Cut the output and power cord andslash the rf shield; use axes, handaxes, ormachetes.

c. Burn. Burn cords and technical man-uals; use gasoline, kerosene, oil flamethrowers,or incendiary grenades.

d. Bend. Bend panels and cases.

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

f. Dispose. Bury or scatter the destroyedparts in slit trenches, foxholes, or throw theminto streams.

36

APPENDIX I

REFERENCES

TM 11-5965-215-15P Repair Parts and Special Tools List and Maintenance Allocation Chart:Headset-Microphones H-101/U and H-10/A/U.

TM 11–6125-204-12P Operator’s and Organizational Maintenance Repair Parts and SpecialTools List and Maintenance Allocation Chart: DynamotorDY-107/AR, DY-107A/AR.

TM 11-6626-203-12 Operation and Organizational Maintenance: Multimeter AN/URM-105,including Multimeter ME-77/U.

37

APPENDIX II

MAINTENANCE ALLOCATION CHART FOR RADIO SET AN/ARC-44


tions and repair operations to be performed bythe lowest appropriate maintenance echelon.


(1)

(2)

Part or component. This columnshows only the nomenclature or stand-ard name. Additional descriptive dataare included only where clarificationis necessary to identify the part.Components and parts comprising amajor end item are listed alphabeti-cally. Assemblies and subassembliesare in alphabetical sequence with theircomponents listed alphabetically im-mediately below the assembly listing.Maintenance function. This columnindicates the various maintenancefunctions allocated to the echeloncapable of performing the operations.

(a)

(b)

(c)

(d)

(e)

( f)

(9)

Service. To clean, to preserve, andto replenish fuel and lubricants.Adjust. To regulate periodically toprevent malfunction.Inspect. To verify serviceabilityand to detect incipient electrical ormechanical failure by scrutiny.Test. To verify serviceability andto detect incipient electrical or me-chanical failure by use of specialequipment such as gages, meters,etc.Replace. To substitute serviceableassemblies, subassemblies, and partsfor unserviceable components.Repair. To restore an item to serv-iceable condition through correctionof a specific failure or unserviceablecondition. This function includesbut is not limited to, inspecting,cleaning, preserving, adjusting, re-placing, welding, grinding, riveting,and straightening,Align, To adjust two or more com-ponents of an electrical system so

(h)

(i)

that their functions are properlysynchronized.Calibrate. To determine, check, orrectify the graduation of an instru-ment, weapon, or weapons system,or components of a weapons system.Rebuild. To restore an item to astandard as near as possible tooriginal or new condition in ap-pearance, performance, and lifeexpectancy. This is accomplishedthrough the maintenance techniqueof complete disassembly of the item,inspection of all parts or compo-nents, repair or replacement ofworn or unserviceable elementsusing original manufacturing tol-erances and/or specifications, andsubsequent reassembly of the item,1st, 2d, 3d, 4th, 5th echelon. T h e(3)

symbol X indicates the echelon re-

(4)

(5)

sponsible for performing that particu-lar maintenance operation, but doesnot necessarily indicate that repairparts will be stocked at that level.Echelons higher than the echelonmarked by X are authorized to per-form the indicated operation.Tools required. This column indicatescodes assigned to each individual toolequipment, test equipment, and main-tenance equipment referenced. Thegrouping of codes in this column ofthe chart indicate the tool, test, andmaintenance equipment required toperform the maintenance function.Remarks. Entries in this column willbe utilized when necessary to clarifyany of the data cited in the precedingcolumns.

c. Columns in the section allocation of toolsfor maintenance functions are as follows:

( 1 ) Tools required for maintenance func-tions. This column lists tools, test,and maintenance equipment requiredto perform the maintenance functions.

(2) 1st, 2d, 3d, 4th, 5th echelon. A dagger

3 8

(†) indicates the echelons allocatedthe facility.

(3) Tool code. This column lists the toolcode assigned.

(4) Remarks. Entries in this column areused to clarify data in the othercolumns.

2. Maintenance by Using OrganizationsWhen this equipment is used by signal serv-

ice organizations organic to theater headquar-

ters or communication zones to provide theatercommunications, those maintenance functionsallocated up to and including fourth echelonare authorized to the organization operatingthis equipment.

3. Mounting HardwareThe basic entries of the maintenance alloca-

tion chart do not include mounting hardwaresuch as screws, nuts, bolts, washers, brackets,and clamps.

3 9

APPENDIX III

BASIC ISSUE ITEMS LIST FOR RADIO SET AN/ARC-44


1. Scopea. This appendix lists items supplied for

initial operation and for running spares. Thelist includes tools, accessories, parts, and ma-terial issued as part of the major end item.End items of equipment are issued on the basisof allowance prescribed in equipment authori-zation tables and other documents that are abasis for requisitioning.

b. The columns are as follows:(1)

(2)

(3)(4)

Source, maintenance, and recoverabil-ity code. Not used.Federal stock number. This columnlists the n-digit Federal stock num-ber.Designation by model. Not used.Description. Nomenclature or thestandard item name and brief identi-fying data for each item are listed inthis column. When requisitioning,enter the nomenclature and descrip-tion on the requisition.

(5)

(6)

(7)

(8)

Unit of issue. The unit of issue is thesupply term by which the individualitem is counted for procurement, stor-age, requisitioning, allowances, andissue purposes.Expendabilitv. Expendable items areindicated by the letter X; nonexpend-able items are indicated by NX.Quantity authorized. Under “ItemsComprising an Operable Equipment”,the column lists the quantity of itemssupplied for the initial operation ofthe equipment.Illustrations. The “Item No.” columnlists the reference designations thatappear on the part in the equipment.These same designations are also usedon any illustrations of the equipment.

2. StockageNo parts authorized for stockage at first

echelon.

51

Section II.

52

APPENDIX IV

BASIC ISSUE ITEMS LIST FOR ANTENNA AT-454/ARC


1. Scopea. This appendix lists items supplied for

initial operation and for running spares. Thelist includes tools, accessories, parts, and ma.terial issued as part of the major end item.End items of equipment are issued on thebasis of allowances prescribed in equipmentauthorization tables and other documents thatare a basis for requisiting.

b. The columns are as follows:(1). Source, maintenance, and recoverabil

ity code. Not used.(2) Federal stock number. This column

lists the 1l-digit Federal stock num-ber.

(3) Designation by model. Not used.(4) Designation. Nomenclature or the

standard item name and brief identi-fying data for each item are listed inthis column. When requisitioning,enter the nomenclature and descrip-tion on the requisition.

(5) Unit of issue. The unit of issue is thesupply term by which the individual

item is counted for procurement, stor-age, requisitioning, allowances, andissue purposes,

(6) Expendability. Expandable items areindicated by the letter X; nonexpen-able items are indicated by NX.

(7) Quantity authorized. Under “Items(’comprising an Operable Equipment”,the column lists the quantity of itemssupplied for the initial operation ofthe equipment. Under “RunningSpares and Accessory I tems.” the quantities listed are those issued ini-t ia l ly with the equipment as spareparts. No parts are authorized to bekept on hand by the operator formaintenance of the equipment.

(8) Illustrations. Not used.

2. Critical ItemsA zero slash (ø) in the "Description" column

indicates items that are expected to fail duringthe f irst year, or i tems that wil l make theequipment inoperative if they fail.

55

APPENDIX V

MAINTENANCE ALLOCATION CHART FOR ANTENNA AT-454/ARC


tions and repair operations to be performedby the lowest appropriate maintenance echelon.


(1)

(2)

Part or component. This columnshows only the nomenclature orstandard item name. Additional de-scriptive data are included only whereclarification is necessary to identifythe part. Components and parts com-prising a major end item are listedalphabetically.

Maintenance function. This columnindicates the various maintenancefunctions allocated to the echeloncapable of performing the operation.

(a)

(b)

(c)

(d)

(e)

( f)

Service. To clean, to preserve, andto replenish fuel and lubricants.

Inspect. To verify serviceabilityand to detect incipient electrical ormechanical failure by scrutiny.

Test. To verify serviceability andto detect incipient electrical or me-chanical failure by use of specialequipment such as gages, meters,etc.

Replace. To substitute serviceableassemblies, subassemblies, and partsfor unserviceable components.

Repair. To restore an item to aserviceable condition through cor-rection of a specific failure orunserviceable condition. This func-tion includes but is not limited toinspecting, preserving, adjusting,replacing, welding, grinding, rivet-ing, and straightening.

Rebuild. To restore to a conditioncomparable to new by disassemb-ling the item to determine the con-dition of its component parts and

(3)

(4)

(5)

reassembling it using serviceable,rebuilt, or new assemblies, subas-semblies, and parts.

1st, 2d, 3d, 4th, 5th echelon. T h esymbol X indicates the echelon re-sponsible for performing that particu-lar maintenance operation, but doesnot necessarily indicate that repairparts will be stocked at that level.Echelons higher than the echelonmarked by X are authorized to per-form the indicated operation.

Tools required. This column indicatescodes assigned each individual toolequipment, test equipment, and main-tenance equipment referenced. Thegrouping of codes in this column ofthe chart indicate the tool, test, andmaintenance equipment required toperform the maintenance function.

Remarks. Entries in this column willbe utilized when necessary to clarifyany of the data cited in the precedingcolumns.

c. Columns in the section allocation of toolsfor maintenance function are as follows:

(1)

(2)

(3)

(4)

Tools required for maintenance func-tions. This column lists tools, test,and maintenance equipment requiredto perform the maintenance func-tions.

1st, 2d, 3d, 4th, 5th echelon. A dagger(t) indicates the echelons allocatedthe facility.

Tool code. This column lists the toolcode assigned.

Remarks. Entries in this column areused to clarify data in the other col-umns.

2. Maintenance by Using OrganizationsWhen this equipment is used by signal serv-

ice organizations organic to theater headquar-

57

ters or communication zones to provide theater 3. Mounting Hardwarecommunications, those maintenance functions The basic entries of the maintenance alloca-allocated up to and including fourth echelon tion chart do not include mounting hardwareare authorized to the organization operating such as screws, nuts, bolts, washers. brackets,this equipment. and clamps.

58

By Order of Wilber M. Brucker, Secretary of the Army:

Official:R. V. LEE,

Major General, United States Army,The Adjutant General

G. H. DECKER,General, United States Army,

Chief of Staff.

Distribution:

Active Army:

To be distributed in accordance with DA Form 12-7 requirements for TM 11 series (Unclas) plusthe following:

USASA (2) 11-67CNGB (1) 11-98Def Atomic Spt Agcy (6) 11-117USARADCOM (2) 11–155USARADCOM Rgn (2) 11-600 AA-AEMDW (1) 11-557Seventh US Army (2) 11-587EUSA (2) 11-592Units org under fol .TOE: (2 each) 11-597

1-26 29-561-27 39-5111-7 39-6111-16 5711-54

NC: State AG (3) Units same as Active Army except allowance is one copy to each unit.USAR: None.For explanation of abbreviations used, see AR 320-50.

* U. S. GOVERNMENT PRINTING OFFICE : 1991 0 - 281-486 (42532)

62

PIN: 022912-003

PIN : 0 2 2 9 1 2 - 0 0 0

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