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TO31R2-2PR-101

TECHNICALMANUALOPERATION,ORGANIZATIONAL,ANDFIELDMAINTENANCEINSTRUCTIONS

RADIOSETAN/PRC-90ANDRADIOTESTSETAN/PRM-32RADIOTEST

SETTS-20/PRM-32A

SYLVANIAELECTRONICSYSTEMSNEEDHAM,MASSFA8501-04-F-0029FA8501-05-D-0002

BASIC AND ALL CHANGES HAVE BEEN MERGED TO MAKE THIS A COMPLETE PUBLICATION

DISCLOSURENOTICE-Thisinformationisfurnishedupontheconditionthat

itwillnotbereleasedtoanothernationwithoutthe

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specificauthorityoftheDepartmentoftheAirForceoftheUnitedStates,thatitwillbeusedformilitarypurposesonly,thatindividual

orcorporaterightsoriginatingintheinformation,whetherpatentedornot,willbe

respected,thattherecipientwillreportpromptlytotheUnitedStates,anyknown

orsuspectedcompromise,andthattheinformationwillbeprovided

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substantiallythesamedegreeofsecurityaffordeditbytheDepartmentofDefenseoftheUnitedStates.Also,regardlessofanyothermarkingson

thedocument,itwillnotbedowngradedordeclassifiedwithoutwrittenapprovalof

theoriginatingUnitedStatesagency.

DISTRIBUTIONSTATEMENTC-Distributionauthorizedto

U.S.GovernmentAgenciesandtheircontractors(AdministrativeorOperationalUse)

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(15February2006).Otherrequestsforthisdocumentshallbereferredto406SCMS/GUEE,Robins,AFB,GA31098.Questionsconcerningtechnicalcontentshallbe

referredtoAFLCMC/WNUS.

WARNING-Thisdocumentcontainstechnicaldatawhoseexport

isrestrictedbytheArmsExportControlAct(Title22,U.S.C.,Sec2751,

etseq.)ortheExportAdministrationActof1979,as

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amended,Title50,U.S.C.,App.2401,etseq.Violationsoftheseexportlawsaresubjecttoseverecriminalpenalties.Disseminateinaccordancewithprovisions

ofDoDDirective5230.25.

HANDLINGANDDESTRUCTIONNOTICE-Complywithdistribution

statementanddestroybyanymethodthatwillpreventdisclosureofcontentsor

reconstructionofthedocument.

PublishedUnderAuthorityof

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theSecretaryoftheAirForce

15FEBRUARY2006CHANGE4-18JANUARY2014

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TO31R2-2PR-101

INSERTLATESTCHANGEDPAGES.DESTROYSUPERSEDEDPAGES.

LISTOFEFFECTIVEPAGES

NOTETheportionof

thetextaffectedbythechangesisindicatedbyaverticallinein

theoutermarginofthepage.Changestoillustrationsareindicatedbyshaded

orscreenedareas,orbyminiaturepointinghands.

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Datesofissuefororiginalandchangedpagesare:

Original.......0.....15February2006Change.......3.......5August2010Change.......1....15December2006Change.......4......18January2014Change.......2....15December2007

TOTALNUMBEROFPAGESINTHIS

PUBLICATIONIS66CONSISTINGOFTHEFOLLOWING:

Page*ChangePage*Change

Page*ChangeNo.No.No.No.No.No.

Title.....................4A.......................

4i-iii....................0ivBlank...................0v-vii....................0viiiBlank..................

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0ix.......................0xBlank...................01-1......................41-2-1-4..................02-1-2-9..................02-10Blank.................03-1-3-8..................04-1-4-3..................04-4Blank..................04-5......................

04-6Blank..................05-1......................05-2......................45-3-5-4..................06-1......................36-2

-6-10.................07-1-7-8..................07-9-7-10.................27-11.....................07-12Blank.................0

*Zerointhiscolumnindicatesanoriginalpage.

AChange4USAF

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TO31R2-2PR-101

TABLEOFCONTENTS

ChapterPageChapterPage

LISTOFILLUSTRATIONS...........iii4.6THEORYOF

SYSTEMOPERATION...................4-1

4.7CONSTRUCTION............4-1

LIST

OFTABLES..................

iii

4.8TRANSMITTERMICROCIRCUITSA1TR1AND

A1TR2........4-1

INTRODUCTION..................v

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4.9MODULATORAMPLIFIERA1AR1..................4-2SAFETYSUMMARY...............ix4.10BEACONANDMCW.........4-2

4.11AMPLIFIER................4-21INTRODUCTION

..................1-14.12RECEIVERMICROCIRCUITSA1RE1ANDA1RE2........4-2

4.13

RECEIVERAMPLIFIERA1AR2..4-2

1.1PURPOSEANDLIMITATIONS..

1-1

4.14ANTENNASWITCHINGCARD

1.2

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AN/PRC-90SERIESRADIOSET.1-1

A1A1...................4-2

1.3AN/PRC-90SERIESRADIOSET

4.15CONTROLCIRCUITS.........

4-2

POWERSUPPLY..........1-2

4.16VOICE/MCW243.0...........

4-3

1.4DESCRIPTION..............1-2

4.17MCWBUTTONIMPRESSED

....4-3

1.5TECHNICALCHARACTERIS

TICS

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...................1-34.18BCN-243.0.................4-3

2OPERATION.....................2-15PREPARATIONFORMAINTENANCE...5-1

2.1GENERAL

.................2-15.1GENERAL.................5-1

2.2CONTROLS,INDICATORS,AND5.2

UNPACKING...............5-1FUNCTIONS.............2-15.3VISUAL-MECHANICALINSPEC

2.3OPERATING

INSTRUCTIONS...2-1TION...................5-1

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2.4OPERATINGPROCEDURE.....2-55.4CLEANING................5-1

2.5BATTERYREPLACEMENT.....2-65.5BATTERYINSPECTION.......5-2

2.6

BATTERYLIFE.............2-65.5.1BatteryLife.................5-2

2.7QUICK

OPERATIONALCHECK.2-65.6BATTERYSERVICELIFETEST.5-2

2.8SERVICEAFTERIMMERSION..2-95.6.1BatteryTest

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UsingMultimeteranda130Ohm1WattResister.....5-2

5.7SERVICELIFETEST.........5-2

3TESTEQUIPMENT

ANDSPECIAL

5.7.1RadioBattery...............5-2

TOOLS.......................

3-1

5.8BATTERYTEST(BA-5368/U)...5-3

5.9BATTERYTEST(BA-5123/U)...5-3

3.1

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TESTEQUIPMENTREQUIRED..3-1

5.10INSPECTIONRECORD........5-4

3.2RADIOTESTSETAN/PRM-32..3-1

5.11INSPECTIONRECORD........5-4

3.3RADIOTESTSETTS-24B

......3-3

3.4TESTSETCALIBRATION......3-4

6

ORGANIZATIONALMAINTENANCE...6-1

3.5CALIBRATIONPROCEDURE

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.

.

.3-6

3.6LOCALLYMANUFACTUREDPARTS..................3-76.1GENERAL.................6-1

3.6.1FabricationofPowerSupplyLeads

.3-76.2PERIODICINSPECTION.......6-1

3.7CALIBRATIONFORTS-20A/PRM-6.3

OPERATIONALCHECKS......6-332A....................3-76.4BATTERYCHECK...........6-3

6.5TRANSMITTERANDRECEIVERTESTSET-UP.............6-3

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4THEORYOFOPERATION............4-1

6.6GUARDCHANNELBEACONTRANSMITTERCHECK.....6-3

4.1GENERAL.................4-1

6.7GUARDCHANNELBEACON

4.2IDENTIFICATIONOFTEST

SIDETONECHECK........6-3

POINTS.................4-1

6.8GUARD

CHANNELMCW

4.3MAJORTESTPOINTS........4-1

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TRANSMITTERCHECK.....6-3

4.4SECONDARYTESTPOINTS....4-1

4.5MINORTESTPOINTS........4-1

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TO31R2-2PR-101

TABLEOFCONTENTS-CONTINUED

Chapter

6.9GUARDCHANNELVOICETRANSMITTERCHECK.....

6.10

ALTERNATECHANNELVOICETRANSMITTERCHECK.....

6.11GUARDCHANNELRECEIVERCHECK

.................

6.12ALTERNATECHANNELRECEIVERCHECK...........

6.13EARPHONE

CHECK..........

6.14REMOVALANDREPLACEMENT..................

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6.14.1BatteryRemovalandReplacement.

6.14.2EarphoneRemovalandReplacement...................

6.14.3AntennaRemovalandReplacement...................

7FIELDMAINTENANCE.............

7.1GENERAL.................

7.2

PRELIMINARYCHECKOUT....

7.3INITIALTESTSETUPFORUSEEXTERNALDC

VOLTAGEINPUT....................

7.3.1InitialTestSetUp

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............

7.3.2OPERATIONINSTRUCTIONS...

7.4TROUBLESHOOTING.........

7.5ACCESSTOTESTPOINTS.....

7.6GUARDCHANNELBEACONTRANSMITTER...........

7.7GUARDCHANNELBEACONSIDETONE

...............

7.8GUARDCHANNELMCWTRANSMITTER...........

Page

6-36-46-76-76-76-86-86-86-8

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7-1

7-17-2

7-27-37-47-77-7

7-7

7-7

7-7

Chapter

7.9

7.10

7.11

7.12

7.13

7.14

7.15

7.16

7.17

7.18

7.19

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7.20

7.21

7.22

7.23

7.24

7.25

7.26

Page

GUARDCHANNELVOICE

TRANSMITTER...........7-7ALTERNATECHANNELVOICE

TRANSMITTER...........7-7GUARDCHANNELRECEIVER..7-8ALTERNATECHANNELRE

CEIVER.................7-8EARPHONECIRCUIT.........7-8ANTENNA

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TIPINSPECTION....7-8DELETED.................7-9DELETED.................7-9REMOVALANDREPLACE

MENT..................7-9ELECTRONICSASSEMBLYRE

MOVAL

.................7-9ELECTRONICSASSEMBLYREIN

STALLATION.............7-9MCWANDPUSH

TOTALK

SWITCHREPLACEMENT....7-9VOLCONTROLREPLACE

MENT..................7-9BATTERYCAPREPLACEMENT.7-9PUSHTO

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TALKORMCWBUT

TONREPLACEMENT.......7-10NAVYMODELPUSHTOTALK

ORMCWBUTTONREPLACE

MENT

..................7-10FUNCTIONSWITCHKNOBRE

PLACEMENT.............7-10RETRIEVALLANYARD

RE

PLACEMENT.............7-11

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AN/PRC-90/90-2AntennaWeight....6-82-4StrapAntennaWeightCheck........2-86-4ElectronicsandSwitchAssembly3-1RadioTestSetAN/PRM-32........3-2

Hold-downScrewsandTestPoints.6-103-2AntennaTestAdapter7-1Load

CarriageAssembly..........7-1MX-8802/PRC-90.............3-47-2RFPowerOutputvsDC

Voltage3-3BatterySupplyTestAdapterReadingatRFPower

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T.P.........7-2MX-8829/PRC-90.............3-47-3RFModuleExternalDCPower3-4CalibrationTestSet..............3-6TerminalLocations............7-33-5Load

ResisterBatteryTest.........3-77-4ExternalDCPowerandTestPoint3-6

FabricationofPowerSupplyLeads...3-7TerminalLocations............7-3

3-7CalibrationTestSet-Up...........3-87-5RFPowerOutput

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vs.DCVoltage4-1SchematicandWiringDiagramofReadingatRFPowerTestPoint...7-4AN/PCRC-90................4-5

LISTOFTABLES

TableTitlePageTableTitlePage

1-1CharacteristicsandLeadingParticularsof3-3CalibrationTestEquipmentRequired..

.3-5theAN/PRC-90................1-33-4AlternateCalibrationTest

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Equipment...3-52-1ControlsandIndicators.............2-36-1PeriodicInspectionand/orTest........6-13-1TestEquipmentRequiredforMaintenance

..................3-33-2SpecialToolsforAN/PRC-90Maintenance..................3-3

iii/(iv

blank)

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TO31R2-2PR-101

INTRODUCTION

1GENERAL.

Thispublicationcoversoperation,organizational,andfieldmaintenanceinstructionsforRadioSet

AN/PRC-90,PartNo.01-524860-1,andRadioTestSetAN/PRM-32,PartNo.01-524930-1,manufactured

bySylvaniaElectronicSystemsEasternDivision,Needham,Massachusetts(refertoFigure1

andFigure3-1).RadioTestSetTS-20/PRM-32Aisalso

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included(refertoFigure2).Allessentialinformationneededtoenableoperatingpersonneltousetheradiosettomaximumadvantageduringsearch,location,

andrescueoperationsiscontainedinthispublication.Aircrewmenissuedthisequipment

areurgedtobecomefamiliarwiththefunctionsofallcontrolsbeforeoperating

theradioset.

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TO31R2-2PR-101

Figure1.RadioSetAN/PRC-90

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TO31R2-2PR-101

Figure2.TestSetTS-20/PRM-32A

vii/(viiiblank)

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TO31R2-2PR-101

SAFETYSUMMARY

1GENERALSAFETYINSTRUCTIONS.

Thismanualdescribesphysicalandchemicalprocesseswhichmay

causeinjuryordeathtopersonnel,ordamagetoequipmentifnotproperly

followed.Thissafetysummaryincludesgeneralsafetyprecautionsandinstructionsthatmustbe

understoodandappliedduringoperationandmaintenancetoensurepersonnel

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safetyandprotectionofequipment.Priortoperforminganytask,theWARNINGs,CAUTIONsandNOTEsincludedinthattaskshallbereviewedandunderstood.

2WARNINGS,CAUTIONS,ANDNOTES.

WARNINGsandCAUTIONsare

usedinthismanualtohighlightoperatingormaintenanceprocedures,practices,conditionsor

statementswhichareconsideredessentialtoprotectionofpersonnel(WARNING)

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orequipment(CAUTION).NOTEsareusedinthismanualtohighlightoperatingormaintenanceprocedures,practices,conditionsorstatementswhicharenotessentialto

protectionofpersonnelorequipment.Theheadingsusedandtheirdefinitionsareas

follows:

Highlightsanessentialoperatingormaintenanceprocedure,practice,condition,

statement,etc.,whichifnotstrictlyobserved,couldresultin

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injuryto,ordeathof,personnelorlongtermhealthhazards.

Highlightsanessentialoperatingormaintenanceprocedure,practice,condition,statement,

etc.,whichifnotstrictlyobserved,couldresultindamageto,ordestruction

of,equipmentorlossofmissioneffectiveness.

NOTE

Highlights

anessentialoperatingormaintenanceprocedure,conditionorstatement.

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3SAFETYPRECAUTIONS.

Thefollowingsafetyprecautionsshallbeobservedwhileperformingproceduresinthismanual.

Cleaningcompound

mayaffectskin,eyesandrespiratorytract.Useinawellventilatedarea.

Avoidprolongedbreathingofvapors.Avoideyeandskincontact.Chemicalgogglesand

neoprenegloveswillbeworn.Keepawayfromsparksand

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flames.Ifnecessarytoremovegreaseandoil,wipetheexteriorwithaclothdampened(notwet)withisopropylalcohol(70%)andwipedry.

TheAN/PRC-90seriesRadiousesaLithiumManganeseDioxidebatteryasits

powersource.Donotshortcircuit,crush,puncturemutilate,ordisassemblebatteries.

TheBA-5368/UbatterycontainsLithiumManganesedioxidemixture.Underconditions

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ofabusemisuse,partialdischarge,ordepletion,willproducegases,fireandexplosions,heat,shortcircuit,crushpuncture,mutilate,ordissemble.Ifone

batteryisweak,excessiveheatingmayresultandtheweakbatterymayexplode.

Batteryisapotentialexplosivehazard.Wearfaceshieldorgoggleswhenhandling

battery.Wearrubbergloveswhenhandlingthebatterytoprevent

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skincontamination.BA-5123/UBatterycontainslithium.Ifliquidcontactsskinoreyes,washaffectedareawithwaterandgetimmediatemedicalattention.The

TestSetshallbegroundedtoearthgroundbymeansofbraidedground

straporshieldedgroundcable,willfurtherattenuateradiationbelowthe35dB

minimumattenuationspecifiedfortheungroundedTestSet.Test

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chambershallbegroundedtoearthgroundbymeansofabreadedgroundstraporshieldedcable.Thisstepwillfurtherattenuateradiationbelow

the35dBminimum.DonotusetheBA-5368/Ubatteriestopowertest

set.Lithiumbatterieswillcausefailuresanderroneousindications,whichcouldcauseand

otherwiseserviceableradiotoberejected.Useonlyexternalpower

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shallbeforallradiotests.ix/(xblank)

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TO31R2-2PR-101

CHAPTER1INTRODUCTION

1.1PURPOSEANDLIMITATIONS.RadioSetAN/PRC-90isadual-channel,self-poweredpersonalemergencyrescue

transceiver,usedprincipallyfortwo-wayvoiceorMCW(modulatedcontinuouswave)communicationsbetween

adownedaircrewmanandarescueaircraft.Provisionsareincludedfortransmitting

tone(MCW)andswept-frequencyhomingbeaconsignalstoguiderescue

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efforts.RadioSetAN/PRC-90iscompatiblewithUHFAMradiosandDirectionFinders.RadioSetAN/PRC-90isdesignedtoprovidethefollowingcapabilities:

a.Two-wayvoicecommunicationsoverarangeof60nauticalmilesto

aircraftoperatingat10,000feetaltitudecanbeexpected.b.AnADF(automatic

directionfinder)rangeof50nauticalmilesandatone

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rangeof80nauticalmilestoaircraftoperatingat10,000feetaltitudecanbeexpected.NOTE

Ingeneral,signalrangeincreasesproportionally

withthealtitudeoftherescueaircraft,providedthatline-of-sightisnotobstructed

Degradationcanbeexpectedwhentheradiosetisoperatedinbadweather

orjungleareas.

RadiotestsetAN/PRM-32/TS-20/PRM-32Ais

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aportableself-containedtestsettoperformoperationalcheckoutsimultaneouslyontwoAN/PRC-90radiosets.Testingisdoneinaclosedcircuitmanner;this

preventstestsfrominterferingwithoperationalradiochannels.

1.2AN/PRC-90SERIES

RADIOSET.TheAN/PRC-90seriesradiosetispoweredbyasingleBA-5368/U

LithiumManganeseDioxide(Li/MnO2).TheLi/MnO2battery(s)providereliablepower

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forradiooperationinalltemperatureenvironments.However,exposuretoextremeheatorcoldcancausebatteryfailureorreducedoperationalefficiency.Therefore,scheduled

checksandinspectionsarerequiredtoassureserviceability.TheBA5368/Ubatteryhas

ashelflifeof60months(5years)fromthedateofmanufacture

andaninstalledservice-lifeof36months(3years).Condemn

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andreplacebatteriesthatexceedserviceorshelflife.CondemnedbatteriesmaybeusedfortrainingordisposedofinaccordancewithTO00-25-213WA-

1.

1.2.1TheAN/PRC-90seriesradiosetcanbepoweredby

asingleBA-5368/U,NSN6135-01-455-7947,(Li/MnO2)battery;hereafterreferredtoasBA-5368/U.NOTE

Whenthebatteryadapter,NSN:5940-01-4846261,P/N

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1794AS0988,isinstalledontheradiotheradiolengthisextendedbyapproximately2inches.Duetothelimitedsurvivalkitspaceinthe

T-6aircraft,thebatteryadapterapplicationisnotauthorizedforradiosplacedin

thisaircraft.ReferenceTO14S-1-131,OperationalandMaintenanceInstructionforSurvivalVest

Assembly,fortheappropriatesurvivalvestpockettoaccommodateradio

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withbatteryadapterinstalled.1.2.1.1BA-5123/U,NSN:6135-01-351-1131,(I.E.approvedcommerciallyavailableCR-123A-Type3VDCphotocellnon-rechargeableLi/MnO2battery),Duracell(P/NDl123A),Eveready(P/N

El123AP),Panasonic(P/NCR123A),Kodak(P/NK123/A),Varta(P/NVl123),Maxwell(P/NCR123),

andSanyo(P/NCR123A)batteriesconformingtoAmericanNationalStandardsInstitute(ANSI)c18.3m

1999,standardparts1&2,areauthorizedforuseasapowersource

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whenthebatteryadapterisusedinplaceoftheBA-5368/U.Batteriesnon-compliantwithANSIc18.3m1999,standardparts1&2,arenotauthorizedforuse.NOTE

AZTSMulti-BatteryTester,NSN6625-01-4949163,PINMBT-Mil,orequivalentwillbe

usedtotesttheBA-5123/UBatteries.TheMBT-MilTesterdisplayscapacitymeasurementsin

incrementsof10%,20%,40%,60%,80%and100%Range.

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1.2.2TheAN/PRC-90seriesradiosetwithabatteryadapter,P/N1794AS0988,NSN5940-01-484-6261,installedcanbepoweredby4BA-5123/U,NSN

6135-01-351-1131,approvedcommerciallyavailable123A-type3VDCphotocellnon-rechargeableLi/MnO2batteries;hereafterreferred

toasBA-5123/U.The4BA-5123/Ubatteriesmustbematchedsetsfromthe

samemanufacturerandwiththesamedatecodes.Thematching

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ensuresthatallBA-5123/Ubatteriesareatthesameapproximatestateofcharge;thus,minimizingthepossibilityofvoltagereversalduringusage.Theuseable

operatinglifeoftheBA-5123/Upowersupplyoptionisapproximately2/3longerthan

thatofaBA-5368/Uwhennewbatteriesareinstalled.TheBA-5123/Uisconsidered

tohaveamaximumshelflifeof120months(10

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years)Change41-1

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TO31R2-2PR-101

fromdateofmanufacture.TheBA-5123/Uservice-lifeis72months(6years),aslongas80%ofitsinitial

capacityisretained.Batteriesfallingbelow80%capacitymaybeusedfortraining.

NOTE

PriortooperatingtheAN/PRC-90seriesradio,

theuser/operatorshallbethoroughlyfamiliarwiththeinformationcontained

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inTO31R22PRC90-1,TO33D7-71-42-1fortheTS-24BRadioTestSet,andmanufacturerscommercialmanual,1002-003S-102,fortheRadioCommunicationsTestSetRCTS

-003.ALSpersonnelusetheTS-24BRadioTestSetstoconducttesting

ontheAN/PRC-90SeriesRadioSet.1.2.3Operationalradiotestingwillbeaccomplished

usingtheTS-24Btestset.Thistestsetshallbe

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operatedusinganexternalDCpowersupplytoprovidepowerforboththeRFandDCmodules.TO33D7-71-42-1containsinformationontheTS-24B

radiotestset.SeeChapters2,4,and5foradditionalinformationon

testing.1.2.4ForBA-5368/UandBA-5123/Ubatteryservice-lifetesting,refertoChapter5.

Typicaldischargecharacteristicsdescribingvoltage(WithTemperatureVariations)profilesfor

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ofthecase.TheBA-5368/Ubatteryshallbeinsertedintoradiobatterywell(+)positiveendfirst.ThepositiveendoftheBA-5368/Ubattery

islabeledwithbothanarrowinsertthisendand+polaritysign.

Theflangepreventspolarityreversal,whichwilldamagetheelectroniccircuitsdueto

improperinstallation.Ifinstalledcorrectly,approximately1/2-inchofthebattery

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isvisibleandthebatterywillspringbackwhenfingerpressureisapplied.NOTE

ReferenceTO14S-1-131,OperationalandMaintenanceInstructionfor

SurvivalVestAssembly,fortheappropriatesurvivalvestpockettoaccommodateradiowith

batteryadapterinstalled.

Thebatteryadapter,NSN5940-01-484-6261,P/N1794AS0988,allows

theAN/PRC-90seriesradiosettouse4BA-5123/Ubatteries

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asapowersource.Wheninstalled,the

adapterextendsthelengthoftheradiobyapproximately2inches.Thecombineduseof

thisadapterand4BA-5123/Ubatterieswillprovideadownedcrewmemberwith

aradiowhichcontainsbatterieswithanoperationalusagelife(i.e.,16to

18hours)approximately2/3overthatofthecurrentBA-5368/U

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battery.

1.4DESCRIPTION.Ingeneral,signalrangeincreasesproportionallywiththealtitudeofthesearchaircraft,providedthatline-of-sightisnotobstructed.

Degradationcanbeexpectedwhentheradiosetisoperatedinbadweather

orjungleareas.

Theoperatorcanselectthreemodesofoperation

ontheguardchanneltoaidinsearch,location,and

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rescueoperations;

a.Thebeaconmodeofoperationtransmitsavariablefrequencywhichsweepsfrom1000to300Hzandthenreturns

instantaneouslytothe1000-Hzfrequencyandrepentsthecycle.Thisoccursata

rateof2to3timespersecond.Theswept-tonesignalisreadily

distinguishablefromothersignalsornoise,andisusedfor

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homingpurposesbythepilotorradiooperatorofanADF-equippedaircraftwhenconductingsearchoperations.TheMCWandbeaconmodesextendthe

one-waycommunicationrangeoftheAN/PRC-90beyondtherangeattainableinthevoice

mode.b.Thevoicemodepermitstwo-wayvoicecommunicationswithanotherAN/PRC-90or

withcompatibleairbornecommunicationsequipment.c.TheMCWmodetransmits

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a1000-HztonewhentheoperatordepressestheMCWbutton.ThismodeisintendedprimarilyforMorseCodecommunicationsincovertsituationswhenused

inconjunctionwiththeearphone.MCWmayalsobeusedforgeneralpurpose

signaling.Onlythetwo-wayvoicecommunicationmodeisavailablewhenoperatingonthe

282.8-MHzalternatechannel.Thevoiceoperatingrangeisthesame

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asfortheguardchannel.Theguardchannelisadistresscallingfrequencyusedtolocatedownedair-crewmen.Oncethemenarelocated,the

alternatechannelmaybeusedforfurthercommunicationsothattheguardchannel

isleftopenforotherdistressoperations.

RadioSetAN/PRC-90has

fouroperatingcontrols:

PUSHTOTALKbutton

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VOLcontrol4-positionfunctionswitchMCWbuttonThecontrolsarcconvenientlylocatedtopermitoperationwitheitherhand.

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TherearepresentlytwotypesofantennasusedontheAN/PRC-90radioset.Oneisafullyflexiblequarter-wave

lengthrubbercoveredwhip;theotherisacombinationflexibleandtelescopichalf-wave

lengthpartiallyrubbercoveredwhip.OnceTimeComplianceTO12R2-2PRC90501iscompliedwith,

thehalf-waveantennaismandatoryforAirForceuse.

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NOTE

Nooperationaltestshallbemadewiththeantennainthestowedposition.

Aminiatureearphoneisprovided

withtheradioset.Theearphone,whichisstoredinacaseon

thecarryingstrap,isintendedtopermitquietoperationoftheradioset.

TheAN/PRC-90isenclosedinaruggedwater-tight

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aluminumcasewhichprotectsinternalcircuits.Theradiosetwilloperatesatisfactorilyafterimmersioninwatertodepthsof50feet.

A

threadedcapatthebottomoftheradiosecuresthebatteryandexternally

sealsthebatterycompartment.Sincethiscompartmentissealedfromtherestof

theradioset,thebatterycanbechangedunderadverse

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weatherconditionswithoutexposinganyelectroniccircuits.

1.5TECHNICALCHARACTERISTICS.Table1-1givescharacteristicsandleadingparticularstoaidinunderstandingthe

capabilitiesandlimitationsoftheAN/PRC-90.

Table1-1.CharacteristicsandLeading

ParticularsoftheAN/PRC-90

a.GeneralWeight18ozwithoutbattery,

24ozwithbatteryExternaldimensions6.0x3.1x

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1.4in(HxWxD)Antennaheight1/4wave,12in.1/2wave,241/2in.Volume26.0cuin.Channelsavailable

tooperator2,fixedfrequency(seeChannelfrequenciesunderb.,below)Operatingtemp,

rangewithoutbattery-30to+50COperatingtemp,rangewithbattery0

to+50CStoragetemperaturewithoutbattery-60to+60

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CHumidity98%Operatingaltitude10,000ftNOTEBeacontransmitteroperatesto40,000feetabovesealevel.Storagealtitude40,000ftSubmersibledepthin

water50ftmaxfor5min2ftmaxfor24hr

b.TransmitterTypicalcommunicationranges(ground-to-air,idealline-of-sightwithaircraftat10,000-ftaltitude)

Voicemode60NMiBeaconmode80NMi

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MCWmode80NMiAutomaticDirectionFinderrange50NMiRFPoweroutput:Voicemode100mwaverage(400mwpeak-envelopepower

min)MCWandbeaconmodes125mwaverage(500mwpeak-envelopepowermin)

Voicepercentmodulation80%minfor115dbsoundpressureatmicrophone(ref

to0.0002dyn/sqcm)Voicedistortion15%maxfor80%

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modulationVoiceaudiobandwidth500-3000Hz+1,-3dbrefto1000HzTypeofvoicemodulationAMGuardchannelfrequency243.0MHz(Voice,

MCW,andBeacon)

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Table1-1.CharacteristicsandLeadingParticularsoftheAN/PRC-90-Continued

Alternatechannelfrequency282.8MHz(Voiceonly)

Frequencystability 0.005%AntennaOmniDirectionalverticallypolarized,half-wave(nominal)orquarterwave

(nominal).Functionswitch4-positionmagneticswitchwithnomechanicallinkageextendingthroughthe

caseEarphoneswitchMagnetonearphoneswitchesspeakeroffand

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earphoneon;nomechanicallinkagesthroughthecase.Earphonemaybeconnectedeitherway(nopolarity).VolumecontrolVariesaudiolevelofreceivedsignals

intheearphoneorspeaker;doesnotvarytransmittedsignallevelortransmitter

sidetonelevel.Reliability800hrMean-time-between-failuresPowersupply+12VDCLithiumManganese

DioxideBA-5368/UInputCurrentDrain40mamaxreceive,(No

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inputsignal)transmitvoice,(Nomodulation)70mamaxtransmittingbeaconorMCWBeaconmodulationwaveshapeRectangularBeaconmodulationdutycycle25 5%

Beaconupper-pulsefrequency1000 200HzBeaconlower-pulsefrequency300 60HzBeacon

sweeprate2-3HzpersecondFrequencysweepdirectionDownMCWmodulationwaveshapeRectangular

MCWmodulationdutycycle25 5%MCWpulsefrequency1000

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200Hzc.ReceiverTypeofCircuitSuperheterodyneSensitivityAtleast10hardvwith30%modulationfor6dbsignal-plusnoise-to-noise[(S+

N)/N]ratioNOTEOnehardmicrovoltisdefinedasthatRFsignalat

theinputofareceiverwhenthereceiverisconnectedthrougha50-ohm

6-dbattenuatortoasignalgeneratorwithitsoutputset

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at1microvolt.Thus10hardmicrovoltsistheRFsignalattheinputofthereceiverwhenconnectedthrougha50-ohm6-dbattenuator

toasignalgeneratorsetfor10microvoltsoutput.SelectivityLessthan-6

dbat 50kHz,Greaterthan-60dbat 10MHzAudiooutput

Atleast6voltsppacross4000ohmsfor30%

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modulationat1kHzfor50to10,000hardvappliedtoinput.Audiofrequency:Response500-3000Hz+2,-5db

refto1000HzDistortion15%maxfor100hardvwith-1

kHz30%modulationwith6voltsppoutputinto4000ohms

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Table2-1.

2.3OPERATINGINSTRUCTIONS.OperationofRadioSetAN/PRC-90isprohibitedexceptduringrescueoperations,emergencyground-to-groundcommunications,orundercontrolled

test/trainingconditions.Falsedistresssignalscanconfuseanddelayrescueoperations.

OperationoftheAN/PRC-90isquitesimple,andisaccomplishedbyfollowingthe

proceduregivenontheoperatinginstructionplate(Figure2-1,15)

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ontheradio-setrearcover.

However,additionalinformationbeyondthescopeoftheinstructionplateispresentedhere,andusersareurged

toreadtheseinstructionsaswellastheprecedingChapterofthismanual

toincreasetheiroverallknowledgeoftheequipment.

TheAN/PRC-90is

normallyoperatedasahand-heldtwo-wayradiowhenoperated

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inthevoicemode.Inthismode,holdtheradiosetineitherhandandoperatethefunctionswitchandPUSHTOTALKswitch

controls.Whentransmittingvoice,holditagainstyourcheekbonesothattheTALK

microphoneisnearyourmouthandtheLISTENspeakerisnearyourear.

TheAN/PRC-90maybeheldclosetoyourearwith

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theVOLcontroladjustedforlowvolume,oritmaybeheldfurtherawaywiththeVOLcontrolturneduptowardMAX.Byusing

theearphone,theradiomaybeheldupto24inchesfromyour

earwhilelistening.

ObservethefollowingprecautionswhenoperatingtheAN/

PRC-90:

a.Sinceitisaline-of-sightcommunications

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Figure2-1.RadioSetAN/PRC-90ControlsandIndicators

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LegendforFigure2-1

1.EarphoneCase2.BatteryCap3.TALKMicrophone4.VOLControl5.

LISTENSpeaker6.EARPHONEJACK7.MCWButton8.PUSHTOTALKButton

9.FunctionSwitchPositionIndicatorandArrowButton10.FunctionSwitchKnob11.

AntennaRetainingLoop11A.Half-waveantennaretainingband12.Earphone

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Connector13.Earphone14.Antenna15.InstructionPlate16.RearCover17.RearCoverHoldingScrews18.Batteryb.Holdtheradiosetso

thattheantennaisessentiallyverticalwhentransmitting(Figure2-2).Thishelpsto

assuremaximumtransmittingrange.NOTE

All5telescopingsectionsofhalf-wave

antennamustbefullyextendedforproperoperation.Abend

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intheantennaofupto20isacceptableandwillnothamperradiotransmission.

c.Conservebatterypowerbysettingfunction

switchtoOFFwhenradiosetisnotinuse.d.Althoughthe

AN/PRC-90circuitsareoperableoveratemperaturerangeof-30to-54C,

thebatterypowersupplyisonlyoperableovera0

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to+20Ctemperaturerange.Operatingatlowtemperaturesreducesbatterylife.MakecertainthattheselectorswitchisnotinadvertentlyleftinBCN243.0

(swept-tone)position.Thetransmitteriskeyedautomaticallywhentheswitchisinthis

position.

e.Whentheradiosetisnotissueditwill

notbestoredwiththebatteryinstalled.Table2-1.Controls

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andIndicators

ControlorIndicatorLocation(Figure2-1)ControlPositionFunctionFunctionswitch9,10OFFVOICE/MCW243.0BCN243.0VOICE282.8

NOTEThebutton,(Figure2-1,9)mustbedepressedtoplacefunctionswitch

intheVOICE282.8position.Completelyremovespowerfromradioset.Turnson

theguardchannelreceivertotheemergencyfrequencyof243.0

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MHz.AlsoenablesvoiceandMCWguardchanneltransmissionwhicharekeyedbythePUSHTOTALKorMCWbuttons.Turnson243.0MHz

guardchanneltransmitter,andtransmitsabeacontone.Sweptaudiotoneiscontinuously

transmittedforrescueaircrafttohomeon.Turnsonalternatechanneltoreceive

on282.8MHz.Alsoenablesvoicetransmissiononauxilliarychannel

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whenPUSHTOTALKbuttonisdepressed.

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Table2-1.ControlsandIndicators-Continued

ControlorIndicatorLocation(Figure2-1)ControlPositionFunctionPUSHTO

TALKbutton8DepressedReleasedTurnsreceiveroffandturnstransmitteronwhen

functionswitchisineitherVOICEMCW243.0orVOICE282.8position.Best

voicetransmissionsareobtainedwhenspokendirectlyintothetalk

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microphone.Turnsofftransmitterandturnsonreceiver;receivedsignalisheardwithearclosetoLISTENspeakerorearphone.MCWbutton7Depressed

ReleasedThisbuttonisatelegraphkey;itenablestheoperatortotransmit

codewhenthenormaltransmittinglevelofhisvoicemayrevealhisposition.

MCWisonlyobtainablewhenthefunctionswitchisin

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theVOICE/MCW243.0position.Causesradiosettotransmitacontinuoustone,receiveroff.Turnstransmitteroff,receiveron.VOLcontrol4Fullyup

MAXFullydownThiscontrolsthevolumeofthesoundfromtheLISTEN

speakerorearphone.Itcontrolsreceivedsignals,notsidetone.LoudestsoundQuietestsound,

butradiosetisnotturnedoff.NOTEVolumecontrol

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doesnotaffecttransmittedpoweroutput.LISTENspeaker5SoundofreceivedsignalisheardbyplacingearclosetoLISTENspeaker.Soundof

MCWorbeacontransmittermayalsobeheard.TheLISTENspeakerisshut

offwhentheearphoneisconnected.TALKmicrophone3Picksupthevoice

beingtransmittedwhenPUSHTOTALKbuttonisdepressedand

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functionswitchissettoeitherVOICE/MCW243.0orVOICE282.8.Earphonejack6EarphoneconnectedNOTEConnectormaybejoinedtojackin

eitheroftwopolarities.EarphonedisconnectedCausessoundtobeheardinearphone.

Amagnetintheearphoneconnector(Figure2-1,12)shutsofftheLISTEN

speaker.SoundisheardthroughLISTENspeaker.Batterycap2

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Holdsbatteryinplace.(Figure2-1,18).

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Figure2-2.AntennaOrientation

f.Lossofspringinessofantennaorcracksandbreaksing.

Batterylifecanbeextendedbyfollowingthetheateritsrubbercoverwill

notdetractfromantennasperforrescueprocedure.mance.Solongasthefullyextended

antennacanbeerectedtoanapproximatelystraightverticalposition

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(by2.4OPERATINGPROCEDURE.bendingtheflexibleportionifnecessary),itwillradiate.These,however,aresignsofdeterioration,andtheantennashouldbe

replacedwhenpossible.Asanoption,TooperatetheAN/PRC-90,proceedasfollows:

theantennacovercanbereplacedbyusinginsulationa.Freetheantenna

fromitsstowedpositionbypullingitssleeving,partnumber

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5-8NTforthebottomportionandendfromtheretainingringorbandasappropriate.Thepartnumber874576fortheupperhalf.antenna

snapsintoanuprightposition.Fullyextendall

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fivetelescopicsectionsofthehalf-waveantennabygraspingitbyitstipandpullingoutward.

NOTE

Bothquarterwaveandhalf-waveantennasarecurrentlyinuseon

thePRC-90radio.Thequarter-waveantennaisfullyflexibleandisapproximately12-inches

long.Thehalf-waveantenna(AirForcerequired)hasaflexible

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lowersectionandatelescopinguppersection.Itslengthisapproximately12-inchescollapsedand24-1/2inchesextended.

Besuretoconnect

theearphonebeforeturningontheradioset,ifquietoperationisdesired

topreventspeakersoundfromdisclosingyourpositiontonearbyenemyforces.

b.Forearphone(quiet)operation,removetheearphonefrom

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itscaseanduncoilthewire.SnaptheearphoneconnectortothetwomatingconnectorsmarkedEARPHONEJACK(Figure2-1,6)ontheradio

set,andinserttheearpieceinyourear.NOTE

Theearphone

connectorfitsineitheroftwopositions(orpolarities)ontheEARPHONEJACK

terminals.

c.Setthefunctionswitchtothe

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desiredmodeofoperation.Thefunctionswitchissetbyrotatingthethumbknobontheright-handsidesothatthearrowpointsto

themodeselected.Thefunctionswitchisdetentedandpositivelycatchesinposition.

Rotatetheknobdownoneclick(fromOFF)forVOICE/MCW243.0operation,or

twoclicksforBCN243.0operation.ForVOICE282.8operation,

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depressthebuttonwiththearrow(Figure2-1,9)androtatethefunctionswitchknob(Figure2-1,10)uponeclick.d.Forvoice

operation,holdtheradiosetinthemannerpreviouslydescribed(RefertoParagraph

2.2)andadjusttheVOLcontrolforthedesired*audiooutputlevelfromthe

LISTENspeakerorearphone.e.Totransmitvoice,depressand

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holdthePRESSTOTALKbuttonandspeakdirectlyintotheTALKmicrophone.f.Ifguardchannelsteady-tonetransmissionorMorsecodeoperationis

desired,setthefunctionswitchtoVOICE/MCW243.0.DepresstheMCWbuttonto

transmitthetone.ListenforthesidetoneintheLISTENspeakerorearphone

whiletheMCWbuttonisdepressed.Thissidetoneindicatesproper

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transmitteroperation.

g.Forguardchannelbeaconoperation,setthefunctionswitchtoBCN243.0.Thetransmittercontinuouslysendstheswept-tonebeacon

signalatthissetting.Listenforthesidetoneasanindicationofproper

operation.Inthebeaconmode,thesidetoneisachirpingsound.NOTE

Sincethetransmitteriskeyedautomaticallyinthebeacon

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mode,andsincecontinuoustransmissionmaybeneededforaprolongedperiodoftime,theAN/PRC-90maybeplaceduprightonaflatsurface.

Itwillthentransmitautomatically.

h.Whenstowingthehalf-waveantenna,

firstcollapsethetelescopicsectionsbyholdingthelowestrigidsection(mid-antennaat

topofrubbersleeving)withonehandandpushinginward

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onthetipoftheantennawiththeotherhand.Stowthecollapsedantennabybendingitdownaroundthecontrolsideofthe

radiosothatthetipoftheantennaisapproximately1-inchbelowthe

modecontrolknob.Sliptheballtipoftheantennacompletelyunderthe

antennaretainingbandsothatthetipextendsbelowthe

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band.Checktomakesurethetelescopingsectionsarestillfullycollapsed.2.5BATTERYREPLACEMENT.Toreplacethebattery,unscrewthebatterycap(rotate

counterclockwise)andslidetheoldbatteryout.Thefreshbatterycanbeinserted

intotheradiosetinonedirectiononly,positiveendfirst.

2.6BATTERYLIFE.Batteriesexceedingaccumulatedserviceandlatestshelf

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lifewillbecondemnedregardlessofcondition.RefertoParagraph5.5foradditionalinformationontotalbatterylifecycleandfieldservicelife.These

batteriesmaybeusedfortrainingpurposes.

2.7QUICKOPERATIONALCHECK.

Thefollowinginstructionsprovideaquickcheckoftheradioset.Theprocedures

areintendedfororganizationalpersonnelwhomustcheckouta

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radiosetwhennotestequipmentisavailable.AsecondRadioSetAN/PRC-90(knowntobeoperatingproperly)must,however,beavailabletoperform

thesetests.TheoperationalcheckoutproceduresinChapter6areamorethorough

testoftheoperatingcapabilityofthe

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AN/PRC-90,andshouldbeusedwheneverpossible.Carryoutthestepsintheorderpresented.

While

performingthesetests,thetransmitteriskeyedandtheradiosettransmits.Always

keepthetransmissiontestasshortaspossible,toavoidinterferingwithrescue

channels.Ifpossible,dothetestinginanauthorizedscreen

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situation,sendtheradiosettofieldmaintenancefacility.c.ConnecttheearphonetotheEARPHONEJACKandholdearpiecenearyourear.NOTE

Youshouldbeabletohearsoundsfromtheearpiecewithout

actuallyinsertingitinyourear.Sinceearwaxwillaccumulateonthe

earpiecewhenitisintheear,donotinsert

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duringcheckout.

(1)IfLISTENspeakerisquietandrushingnoiseisheardinearpiece,disconnectearphoneandproceedtostepd.

(2)Ifrushingnoiseisnotheardinearpiece,replacetheearphoneand

repeatthetest.Ifrushingnoiseisstillnotheard,sendtheradio

settofieldmaintenancefacility.(3)Ifrushingnoiseis

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heardinLISTENspeakerwhenearphoneisconnected,replacetheearphoneandrepeatthetest.Ifrushingnoiseisstillheardinthespeaker,

sendtheradiosettofieldmaintenancefacility.d.Onthesecondradio

set,depressthePUSHTOTALKbuttonandblowintotheTALKmicrophone.

(1)IfblowingsoundisheardintheLISTENspeaker

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oftheAN/PRC-90undertest,proceedtostepe.(2)Ifblowingsoundisnotheard,sendtheradiosettofieldmaintenancefacility.

e.Onradiosetundertest,depressPUSHTOTALKbuttonandblow

intoTALKmicrophone.(1)IfblowingsoundisheardinLISTENspeakerof

secondradioset(adjustsecondradiosetsVOLcontrolif

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necessary),proceedtostepf.(2)Ifblowingsoundisnotheard,sendradiosetundertesttofieldmaintenancefacility.f.Onradio

setundertest,depressMCWbutton:(1)IftoneisheardinLISTEN

speakerofbothradiosets,proceedtostepg.(2)Iftoneis

notheardinbothspeakers,sendradiosettofield

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maintenancefacility.g.OnAN/PRC-90radiosetundertest,setfunctionswitchtoBCN243.0forasecondandthensettoOFF.(1)

IfchirpingsoundisheardinLISTENspeakerofsecondradiowhileradio

setundertestissetforbeaconoperation,proceedtosteph.(2)

Ifchirpingsoundisnotheard,sendradiosetto

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fieldmaintenancefacility.h.SetthefunctionswitchesonbothradiosetstoVOICE282.8.

(1)Ifadefiniterushingnoiseis

heardinLISTENspeakerofradiosetundertest,proceedtostepi.

(2)Ifrushingnoiseisnotheard,sendradiosettofieldmaintenance

facility.i.Onsecondradioset,depressPUSHTOTALK

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switchandblowintoTALKmicrophone.(1)IfblowingsoundisheardinLISTENspeakerofradiosetundertest,proceedtostepj.

(2)Ifblowingsoundisnotheard,sendradiosettofieldmaintenance

facility.

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Figure2-3.AntennaBracketWeightCheck

Figure2-4.StrapAntennaWeightCheck

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noiselevelvariationissuddenorintermittent,sendtheradiosettofieldmaintenancefacility.NOTE

AlthoughanAN/PRC-90passesthequick

operationalcheck,itmayhaveaweakbattery,lowreceiversensitivity,orlow

poweroutput.TheoperationalcheckoutinChapter5isrequiredtoassureproper

operation.

2.8SERVICEAFTERIMMERSION.Iftheradio

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sethasbeenimmersedinsaltwater,washitinfreshwaterassoonaspossible.Sometimesanaccumulationofdriedsaltcausesthe

functionswitchtobind.Iftheradiosethasbeenimmersedineither

saltorfreshwatertoadepthgreaterthan50feet,sendit

toorganizationalmaintenanceforinspection.

2-9/(2-10blank)

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CHAPTER3TESTEQUIPMENTANDSPECIALTOOLS

3.1TESTEQUIPMENTREQUIRED.Table3-1listsanddescribesthe

useoftestequipmentrequiredfororganizationalandfieldlevelmaintenanceofRadio

SetAN/PRC-90.SpecialtoolsarelistedinTable3-2.

3.2RADIO

TESTSETAN/PRM-32.RadioTestSetAN/PRM-32(Figure3-1)is

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RadioTestSetAN/PRM-32/TS-20/PRM-32Aprovidesafullyshieldedtestpath.Thus,byusingthetestsetfortransmittertests,thereisnointerferencewith

operatingchannels.

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3.3RADIOTESTSETTS-24B.RadioTestSetTS-24Bisusedbylifesupportshopsinthecheckoutof

theAN/PRC-90radio.TestradioinaccordancewithParagraph7.3.

Table

3-1.TestEquipmentRequiredforMaintenance

NameANTypeorDesignation

AlternateUseVariablePowerSupply0-30VDCOscilloscope30-dbstep

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attentuatorFrequencycounterMultimeterRadiotestsetRadiotestsetPullScaleBKPrecisionMod#:1651ATektronix545Awithplug-inadapterAN/USM-26FLUKE8000,

or27Aor87MultimeterorEquivalentPRM-32TS-24BNSN6625-01-1288588LSModel80D

EquivalentTektronix317HP-524B,HP-525Cplug-in,HP5245LwithHP-5253Bplug-inT5-20/PRM-32AAny10

lb.wt.SupplyexternalDCpowerVisualcomparisonsoffrequencies

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andwaveformsUsedwithfrequencycounterFrequencychecksFieldlevelDCMeasurements/Tests.OrganizationalcheckoutFieldlevelcheckoutandtroubleshooting.Apply10lb.Pull

toantennatip.

Table3-2.SpecialToolsforAN/PRC-90Maintenance

FigureandIndexNumberPartNumberNomenclatureUseandApplicationFigure6-1

MX-8801/PRC-90BatterytestadapterBatterytesting,withBatteryTesterTS-2530/UR

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Figure3-2MX-8802/PRC-90AntennaTestAdapterConnectionofradiosetantennajacktoBNCseriesconnectorsFigure3-3MX-8829/PRC-90BatterySupplyTestadapterFeeler

gagesfor0.004through0.010inchSupplypowertoradioduringmaintenance.Check

ofclearanceofbuttonsandswitchesFigure7-4,671-485750-1SpannerWrenchNavy

modelsonly;replacementofbuttons(suppliedwithsparebuttonassemblies)

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Figure3-2.AntennaTestAdapterMX-8802/PRC-90

Figure3-3.BatterySupplyTestAdapterMX-8829/PRC-90

3.4TESTSETCALIBRATION.CalibrationoftheCategoryIIPMELsupportedtestset

canbeperformedusingthefollowingprocedures.Table3-3liststhetestequipment

requiredtoperformthecalibration.Equivalenttestequipmentmaybe

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substitutedasrequired.Calibration/certificationintervalisinaccordancewithTO33K-1-100.ThePRM-32willbecalibratedandcertifiedtowithin5%ofinput

levelspecified.TheTS-20/PRM-32AwillbecalibratedinaccordancewithParagraph3.5.

a.ConnecttestequipmentandtestsetasshowninFigure3-4.

b.Turnsignalgenerator,frequencycounterandpoweramplifierswitch

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toON.Allowequipmenttowarmupforapproximately15minutes.c.PlacesignalgeneratorMODSELECTORswitchtoCW,FREQUENCYRANGEselectorto

E,and-OUTPUTATTENUATORcontrolto50MV.d.PlacefrequencycounterFUNCTIONswitch

toFREQUENCY,TIMEBASEswitchto10MS,andSENSITIVITYswitchtoPLUG-IN.

e.AdjustFREQUENCYknobonsignalgeneratorfora243.0

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MHzindicationonfrequencycounter.f.Setpowermetersothatitwillindicateuptoonewattintheregionof200to

300MHz.Placetheresistiveelementwithitsarrowpointingtowardtheload

end.g.Placethepoweramplifierbandswitchtothe125-250position

andtuneamplifieruntiltheFREQUENCYMC

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h.dialindicates243.0MHzandapowerindicationisobservedonthepowermeter.PlacesignalgeneratorMOD

SELECTORswitchto1000Hzposition(1000Hz,internalmodulation),andadjustthe

MODlevelcontroluntilareadingof80isobtainedontheMODULATION

PERCENTAGEmeter.k.l.ReplacecoverovertheSIGADJ

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potentiometer.Adjustoutputofthesignalgeneratoruntilthepowermeterindicates31milliwattsaveragepower.Markmeterindicationonmeterface.Usecloth

tape,markerpenorsuitablemeanstoindicateneedlepositiononscaleface.

i.Adjustoutput,attenuatorofthesignalgeneratoruntilthepowermeterindicates

100milliwattsaveragepower.NOTEj.Removecoverfromthe

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SIGADJpotentiometerofthetestset.Usescrewdrivertoadjustpotentiometeruntilthemeterindicatesmid-scale(red-greenintersection).Thismarkisthego-on-go

testpointfortrainingradios.

Table3-3.CalibrationTestEquipmentRequired

TestEquipmentTypeorModelNo.ManufacturerSignalGeneratorVHFPower

AmplifierPowerMeterIn-LinePowerMeterElement1watt200

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-300MHzInterconnectingCablesAttenuationMeasurementSystem20DBDirectionalCouplerPowerMeter/ThermistorMount8640BorAN/USM323230B4312200-1RG223U12953039-20

432B/478AHewlettPackardHewlettPackardBirdBirdLocalMicro-TelNARDAHewlettPackardNOTE

SubstitutesofequipmentindicatedinTable3-3maybemadeas

longasaccuracyandoperatingcharacteristicsarenotcompromised.If

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thespecialBNCconnector,PartNoMX-8802,isnotreadilyavailable,localshopmanufactureisauthorized.

Table3-4.AlternateCalibrationTestEquipment

TestEquipmentTypeorModelNo.ManufacturerUnitOscillatorPowerSupply

AudioOscillatorPowerOscillatorPowerOscillatorFrequencyCounter1209CL1201-C208125408

BAN/USM-26GeneralRadioGeneralRadioHewlett-PackardAirborneInstLabs

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Figure3-4.CalibrationTestSet

m.Disconnecttestsetup.Testsetisnowreadyfor

use.3.5CALIBRATIONPROCEDURE.Preparetestsetupinaccordancewithinstructionscontainedin

Figure3-4andperformtheprocedureasfollows:

a.Connecttest

equipmentandtestsetasshowninFigure3-4.NOTE

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ThefollowingprocedureisforuseonlywithNavyPRC-90radiosmadeundercontractN00019-67-C-0098.UseprocedurestartingwithParagraph3.4when

testingallotherPRC-90radios.

Interconnectingcablesmustbeshort

aspossible.Longcableswillintroduceexcessivelossesandcalibrationwillnotbe

accurate.

b.Turnsignalgeneratorandpoweramplifier

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powerswitchtoON.c.TurntheFREQUENCYknobuntilMEGACYCLEdialindicates243onbandE.PlacetheFREQUENCYRANGEselectoratE.

PlacetheMODSELECTORswitchatCW.d.Setpowermetersothatitwill

indicateuptoonewattintheregionof200to300MHz.

Placetheresistiveelementwithitsarrowpointingtowardthe

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loadend.e.Placepoweramplifierbandswitchtothe125-250positionandtuneamplifieruntiltheFREQUENCYMCdialindicatesapproximately243

MHz.f.Setsignalgeneratoroutputattenuatorcontroltominimumlevel;then,advance

controltoincreaseoutputuntilanindicationofsignalisobservedonpower

meter.g.Tunepoweramplifier(byadjustingittoeither

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sideofthe243MHzposition)untilamaximumreadingisobservedonthepowermeterh.PlacesignalgeneratorMODSELECTORtothe

1000position(1000Hzinternalmodulation)andadjusttheMODlevelcontroluntil

areadingof80isobtainedontheMODULATIONPERCENTAGEmeter.i.Adjust

outputattenuatorofthesignalgeneratoruntilthepowermeter

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indicatesexactly81milliwatts,averagepower.

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j.RemovecoverovertheSIGADJpotentiometerofthetestset.Usescrewdrivertoadjustpotentiometeruntil

themeterindicatesmid-scale(RED-GREENINTERSECTION).k.ReplacecoverovertheSIG

ADJpotentiometer.Disconnecttestsetup.Thetestsetisnowreadyforuse.

3.6LOCALLYMANUFACTUREDPARTS.TotestradioswhenLithiumbatteries

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areuseda130Ohmresisterandanextensionwireattachedisrequired.SeeFigure3-7.

3.6.1FabricationofPowerSupplyLeads.

Powersupplyleadsmaybecommerciallyprocuredorcanbelocallymanufactured,obtain

thefollowing:Twosetsofpowerleadseithercommercialorlocallymanufactured.

SeeFigure3-6.Onesettoconnectpowersupply

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toRFmoduleassemblyexternalpower.Onesetwitha15ohm1%,1wattresisterinlineonpositiveleadtoconnect

theregulatedpowersupplyDCmoduleassemblyAN/PRC-90/-106externalpowerontheTS-24B.

NOTE

A15ohm1%,1-wattminimumresistermustbesoldered

inlineonpositive(red)terminalwire.Thepurposeof

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thisresistoristolimitinrushcurrentthroughtheradiosreedswitchestopreventdamage.

Figure3-5.LoadResisterBattery

Test

Figure3-6.FabricationofPowerSupplyLeads

a.Cutpositiveleadwireapproximately3inchesbackfromtheenddetermined

tobeconnectedtothepowersupply.(1)Stripinsulation

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eachleadwiretinbarewiretopreventfraying.Solderthe15Ohm1%,1-Wattresistorbetweenthetwofreeendsonredor

positivepowerleadwire.Thisactionplacesthelimitresisterbetweenthepower

supplyandtheDCpowermodule.b.Thelinessupplyingpowertothe

testsetrequireatleastsixbananatypetestplugs

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beinstalledifnotpreviouslyonthepowersupplyleads.c.Cutandremoveanyunusableitemssuchastestprobesfromtheends

ofleadwires,removeinsulationfrompreviouslyexposedends.Onlyremoveenoughinsulation

toinsertintothetypebananaplugbeingused.Installorsolderon

endofleadwire.3.7CALIBRATIONFORTS-20A/PRM-32A.a.Determine

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theratioofthepowerfromtheoutputporttothecoupledportofthe20dBdirectionalcoupler,using

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themicrotel1295at243.0MHzand121.5MHz.Recordtherespectivevalueofattenuationateachfrequency.

b.Calculatethecorrectionfactorforeachfrequencyasshowninthe

followingexample,i.e.:(1)121.5MHzoutputtocoupledportis20.472dB.

(2)Divide20.472by10=2.0472.(3)Obtainthe

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antilogof9.0472=111.481=correctionfactor.(4)For100mwintotheTS-20/PRM32A,divide100mwbythecorrectionfactor

todeterminetheindicatedreadingfortheHP432B/478A.100/111.481=0.897mw.c.

ConnecttestequipmentasshowninFigure3-7.NOTE

Tocalibrate

thetesterforfrequency243.0MHzseestepsd,c

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andf.Forcalibrationoftesterforfrequency121.5MHzusestepsi,jandk.

d.Tunesignalgeneratorandthe

230Bpoweramplifierto243.0MHz 3kHz,adjusttheoutputuntilthe

HP432B/478Aindicatesthecalculatedvaluefor243.0MHz.e.Adjustthesignal

generatoroutputfor80%,1kHzAMmodulation.f.Adjust

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outputuntiltheHP432B/478Aindicatesthecalculatedvaluefor243.0MHz.g.Adjust243/282.8calformidscale(red-greenintersectional)meterreading.h.SetRF

outputonsignalgeneratorto-80DBM.i.Tunesignalgeneratorandthe

230Bpoweramplifierto121.5MHz 3kHz,adjusttheoutputuntilthe

HP432B/478Aindicatesthecalculatedvaluefor121.5MHz.j.

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Adjustthesignalgeneratoroutputfor80%,1kHzAMmodulation.k.AdjustoutputuntiltheHP432B/478Aindicatesthecalculatedvaluefor121.5MHz.

l.Select121.5MHzontheTS-20/PRM-32Aandadjust121.5calformidscale

(red-greenintersection)meterreading.Figure3-7.CalibrationTestSet-Up

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CHAPTER4THEORYOFOPERATION

4.1GENERAL.ThisChaptercontainsabrieffunctionaldescriptionoftheoperation

ofRadioSetAN/PRC-90.Whereapplicable,asystemoftest-pointidentificationisincorporated

asanaidintroubleshootingandmaintainingtheradioset.

4.2

IDENTIFICATIONOFTESTPOINTS.Onapplicableillustrations,tables,andtext,

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asystemoftest-pointidentificationisusedtoaidintroubleshootingandmaintenance.Anexplanationoftest-pointidentificationisincludedhere.Someofthe

testpointsareusedonlybydepotmaintenance,andthereforearenotreferenced

intheproceduresofthisTechnicalOrder.

4.3MAJORTESTPOINTS.

Amajortestpointisusedforcheckingtheoverall

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functionsof,andlocalizingtroubleto,assemblieswhichtogethercompriseaprimaryfunctionalloop;groupsofcomponents;andindividualcomponents.Theidentificationsymboldesignating

majortestpointsconsistsofanarabicnumeralenclosedin

.

Textandtabularreferencestomajortestpointsarewrittenasfollows:test

point1,testpoint2,etc.4.4SECONDARYTESTPOINTS.

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Asecondarytestpointisusedtoisolatecausesofsubnormalperformancewithinaspecificassemblyorsubassembly.Thesymboldesignatingsecondarytestpoints

consistsofacapitalletterenclosedinacircle

.Text

andtabularreferencestosecondarytestpointsarewrittenasfollows:testpoint

A,testpointB,etc.

4.5MINORTEST

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OFSYSTEMOPERATION.AfunctionalschematicandwiringdiagramofRadioSetAN/PRC-90,Figure4-1,illustratesthemodularandswitchingconceptoftheradio

setandtherelatedinterconnections.

4.7CONSTRUCTION.Theprimaryelectronicfunctions

oftheradiosetareperformedbysixmicrocircuitswhicharetotallyenclosed,

non-repairablemodules.Thegeneralinternalfunctioningofthemicrocircuitslisted

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belowisshowninFigure4-1,toaidinunderstandingthetheoryofoperationandtoassisttroubleshooting.

a.A1TR1GuardChannel

Transmitterb.A1TR2AlternateChannelTransmitterc.A1RE1GuardChannelReceiverd.A1RE2

AlternateChannelReceivere.A1AR1ModulatorAmplifierf.A1AR2ReceiverAmplifierThesix

microcircuitsaremountedonaninterconnectingprinted-circuitboardA1A2,together

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withantennaswitchA1A1.Therearealsoseveralindividualcomponents(crystals,diodes,andresistors)mountedonA1A2.Theremainingcomponentsaremountedonthe

radiosethousingandarenotpartofelectronicsassemblyA1.

4.8TRANSMITTERMICROCIRCUITSA1TR1ANDA1TR2.Bothtransmittermicrocircuitsfunctioninasimilar

manner;theyconsistofacrystaloscillator,afrequencydoubler

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andanamplifier.The243.0MHzguardchanneltransmittergeneratesitsfrequencywitha121.5MHzcrystaloscillator,doublesthisfrequencyto243.0MHz

inadoubler,andappliesthissignaltoadriverandfinalamplifier

wherethesesignalsareamplifiedtothecorrectpowerandimpedancelevelfor

matchingoftheantenna.TheRFsignalisamplitudemodulated

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byaudiofluctuationsontheDCpowerinputtothefinalamplifier.ThepresenceofmodulatedRFatthefinalamplifiercausesanaudio

signaltobedetectedbythesidetonedetector;thissignalisdirectlyapplied

totheLISTENspeakerthroughattenuatingresistorA1A2R2andproducesthesidetone.The

282.8MHzalternatechanneltransmittergeneratesitsfrequency

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witha70.7MHzcrystaloscillator,doublesitsfrequencytwiceintwodoublerstagestoproduce282.8MHz.Thesignalisamplifiedina

finalamplifier.Wheremodulationisappliedonthepositivepowerlinethereis

nosidetoneconnectioninthealternatechanneltransmitter.

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4.9MODULATORAMPLIFIERA1AR1.ThismicrocircuitdevelopsaudiosignalswhichmodulatetheRFinthefinalamplifiersofthe

guardandalternatechanneltransmitters.

4.10BEACONANDMCW.Asingle

audio-tonegeneratoriscommontoboththebeacongeneratorandMCWtone.When

thebeaconmodeisselectedthesweepgeneratorproducesa

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2.5Hzsaw-toothwhichsweepsthetonegeneratorfrequencyfromapproximately1000Hzto300Hzatarateoftwoorthreecycles

persecond.WhenMCWisselected,thesweepgeneratorismadeinoperativeand

thetonegeneratorproducesasingletoneof1000Hzinaccordancewith

thedepressionoftheMCWbutton.ThebeaconorMCW

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signalisthenamplifiedbythemodulator.ThebeaconandMCWsignalsareappliedtothetransmittersonthesamelineasthevoice

modulationsignals.Onlytheguardchanneltransmitterismodulatedbythebeaconand

MCWsignals,becausethecontrolcircuitsdonotactivatethetoneandsweep

generatorsinthealternatemode.

4.11AMPLIFIER.This

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circuitonA1AR1isaspeechamplifierwhichraisesthelow-levelsignalsfromtheTALKmicrophoneorbeaconandMCWsignalssufficientlytodrive

themodulator.TheoutputofA1AR1isthenroutedtothefinalamplifiers

ofbothtransmitters,wheretheselectedintelligenceamplitudemodulatesthecarrierwave.

4.12RECEIVERMICROCIRCUITSA1RE1ANDA1RE2.Bothreceivermicrocircuits,

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channelreceiverA1RE2,thelocaloscillatoroperatesfromthethirdovertoneof89.933MHzcrystalY2toproducethe

251.799MHzLO

signal.Inbothreceivers,theLOiscoupledtothemixercircuitto

produceanintermediatefrequencyof31MHz.The31MHzIFisamplified,

detected,andre-amplifiedtoaudiolevelssufficienttodrive

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receiveramplifierA1AR2.4.13RECEIVERAMPLIFIERA1AR2.TheaudiofrombothreceiversisappliedthroughVOLcontrolR1totheinputofreceiveramplifier

A1AR2.Receiver

AmplifierA1AR2amplifiesthereceivedaudiosignalstoa

powerlevelsufficienttodriveLISTENspeakerLS1orearphoneLS3.

4.14ANTENNASWITCHINGCARDA1A1.Thiscardprovidesthenecessary

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circuitryforroutingsignalsto,orfrom,theantennaterminalstotheoutputterminalsofthetransmittersandinputterminalsofthereceivers.Terminals

3,5,6,and10arecontrolterminalsthat,whenmadepositivewith

respecttoterminals1and11bybatteryvoltage,willcausediodesCR1,

CR2,CR3,andCR7toconductandthusprovidea

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lowimpedancesignalpathfromtheantennatoterminals2,4,7and9.Thecardalsoroutesthepositivepowersupplyvoltagefrom

terminal8toactivatetheamplifieronA1AR1,wheneitherguardoralternate

channeltransmitfunctionsareselected.ThisDCvoltageisalsoappliedthroughCR5

toreversebiasandcutoffdiodesCR1andCR2

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A1A2CR4,andtopin5ofantennaswitchA1A1.AtA1A1-5itcausesdiodeA1A1CR2toconductandthusconnectstheantenna

terminals,throughdiodeA1A1CR2andA1A1pin4andfinallytothe

inputofalternatereceiverA1RE2atpin2.Thedetectedlow-levelaudiofrom

thisreceiveratpin11passesthroughVOLcontrolR1

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andthentopin4ofreceiveramplifierA1AR2.TheamplifiedoutputatA1AR2-3passesthroughthenormally-closedcontactofEARPHONEJACKswitch

S6toLISTENspeakerLS1.Whentheearphoneispluggedin,themagnet

mountedinsidetheplugactuatesreedswitchS6insidethehousing.Thereed

switchroutestheaudiooutputsignaltotheearphoneand

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providesB+at

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pin8,thusturningonmodulatoramplifierA1AR1,viapins3and4.Amodulatingsignalisroutedtopin8ofalternate

transmitterA1TR2.

4.16VOICE/MCW243.0.Withthefunctionswitchinthis

position,switchSlappliesB+throughthenormally-closedcontactofMCWswitchS4

andnormally-closedcontactsofPUSHTOTALKswitchS5to

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pin3ofguardreceiverA1RE1andtopin3ofantennaswitchA1A1.HeretheB+causesdiodeA1A1CR1toconduct,and

thuscompletestheantennacircuittopin2ofguardreceiverA1RE1.B+

isalsoappliedtopin2ofreceiveramplifierA1AR2throughdiodeA1A2

CR3.Low-levelaudiofrompin11ofA1RE1passesto

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pin4ofreceiveramplifierA1AR2.Theresultinghigh-levelaudiodrivesLISTENspeakerLS1.Transmittingon243.0MHzisaccomplishedbydepressingthePUSH

TOTALKbutton.Thisaltersthecontrolvoltage(B+)asdescribedbelow:

a.RemovesB+frompin3ofguardreceiverA1RE1andpin

2ofreceiveramplifierA1AR2,shuttingthosecircuitsoff.b.

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RemovesB+frompin3ofantennaswitchA1A1,therebyopeningthesignalpathfromtopin2ofthereceiver.c.AppliesB+

topin2ofguardtransmitterA1TR1.d.AppliesB+topin3

ofantennaswitchA1A1,therebyclosingtheantennacircuitpathfrompin11

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e.AppliesB+(frompin6ofantennaswitchA1A1throughdiodeA1A1CR3topin8ofthiscard)frompin8

oftheantennaswitchingcardtopins3and4ofmodulatoramplifier

A1AR1.4.17MCWBUTTONIMPRESSED.WiththefunctionswitchinVOICE/MCW243.0position,

switchS1appliesB+toMCWswitchS4.DepressingMCW

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switchS4appliesB+tothefollowingcircuits:

a.Pin2ofguardtransmitterA1TR1throughisolationdiodeA1A2CR1.b.Pin

6ofantennaswitchA1A1,closingtheantennacircuitpathfromA1TR1pin

11totheantenna.c.Pin9ofmodulatoramplifierA1AR1,turningon

thetonegenerator.4.18BCN-243.0.Withthefunctionswitchin

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thisposition,switchS3appliesB+tothefollowingcircuits:

a.Pin6ofantennaswitchA1A1throughisolationdiodeA1A2CR2;

thisclosestheantennacircuitpathfrompin11ofguardtransmitterA1TR1

totheantenna.B+isalsoappliedtopin2ofguardtransmitter

A1TR1,turningontheoscillator.b.Pin11ofmodulator

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amplifierA1AR1,turningonthebeacontonegeneratorandsweepgenerator.4-3/(4-4blank)

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TO31R2-2PR-101

Figure4-1.SchematicandWiringDiagramofAN/PCRC-90

4-5/(4-6blank)

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TO31R2-2PR-101

CHAPTER5PREPARATIONFORMAINTENANCE

5.1 GENERAL.ThisChapterdescribestheworknecessarytoprepareRadioSetAN/PRC-90

fororganizationalandfieldmaintenance.Thisserviceisalsorequiredbeforeissuingthe

AN/PRC-90toaircrewmen.

5.2 UNPACKING.Thecompleteradiosetandbattery

areshippedinastandardpackage,andthereforerequireno

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unpackinginstructions.

5.3 VISUAL-MECHANICAL INSPECTION.Inspecttheequipmentexteriorforcleanlinessandproperoperationofallcontrols.Checkthatfunctionswitchturnswithproper

detentactionwithoutbinding,thatMCWandPUSHTOTALKbuttonsreturnwhen

depressed,andthatVOLcontrolturnsfreelyandstopsatMAXandminimum

limits.CheckthatperforationsatTALKandLISTENareclear,

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antennaiscleanandsnapstotheerectpositionwhenreleasedfromthestowedposition,andthattelescopicsectionsoftheantennacanbe

fullyextendedandcollapsed;thattheantennaretainingbandisnotcracked,deteriorated,

oroutstretched,andthatcontrolmarkingsandidentificationandinstructionplatesareclean

andlegible.

NOTE

Someantennashave

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aloose-fittingrubbercoverwhichmayhaveatwistedorwrinkledappearance.Theantennaisnotdefectiveunlesstherubberiscrackedorbroken

ortheuncoveredtelescopicsectionsdonotextendandcollapsefully.

WhenusingCleaningCompoundFSN6850-5979765avoidprolongedinhalationofthefumes.

Provideampleventilationandkeepawayfromflame.

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5.4 CLEANING.Cleaningcompoundmayaffectskin,eyesandrespiratorytract.Useinawellventilatedarea.Avoidprolongedbreathingofvapors.Avoideyeand

skincontact.Chemicalgogglesandneoprenegloveswillbeworn.Keepawayfrom

sparksandflames.Ifnecessarytoremovegreaseandoil,wipetheexterior

withaclothdampened(notwet)withisopropylalcohol(70%)

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andwipedry.

Cleantheequipmentbywipingwithacleanlintfreeclothorsoftbrush.

Iftheradio

sethasbeenexposedtosaltwaterorifsuchexposureissuspected

becauseofdifficultyinoperatingthefunctionswitch,washtheradiosetin

freshwater.Todothis,immersetheentireradioin

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abasinoffreshwaterandagitatewhileoperatingthefunctionswitch.Ifrepeatedfreshwaterwashingdonotfreethefunctionswitch,send

theradiosettofieldmaintenancefordisassembledcleaningorreplacementofthe

functionswitch.

Batteryleakagecreatesabuildupofacausticand

corrosivechemicalonthebatterycap,springs,andbatterywell,

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whichwilleventuallycausetheradiosettomalfunction.

a.Cleanbatterycapasfollows:(1)Removespringandsealingwasherfrom

thebatterycap.(2)Soakspring,washer,andcapinequalpartsof

vinegarandhotwaterfor30minutes.(3)Carefullyscruboffanyremaining

chemicalsothatallsurfacesareclean.

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TO31R2-2PR-101

b.Ifthebatterywellortopspringiscorrodedsendtheradiotofieldmaintenance.Fieldmaintenanceactivities

willcleanandtreatcorrodedareasasoutlinedinTO12R2-2PRC90-3.c.Dry

andreassemblethebatterycap.Ifseriouspittinghasoccurred,replacethefaulty

parts.5.5BATTERYINSPECTION.NOTE

TheBA-5368/Ubattery

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hasashelflifeof60months(5years)fromthedateofmanufactureandaninstalledservice-lifeof36months(3years).Condemn

andreplacebatteriesthatexceedserviceorshelflife.Condemnedbatteriesmaybe

usedfortrainingordisposedofinaccordancewithTO00-25-213-WA-1.

5.5.1BatteryLife.Removethebatteryfromtheradioset

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andinspectforevidenceofswelling;chipped/crackedsurfacesformoisture.Ifanyoftheseconditionsarepresent,thebatterywillbecondemned.TheBA-5368/U

batteryhasashelflifeof60months(5years)fromthedate

ofmanufactureandaninstalledservice-lifeof36months(3years).Condemnand

replacebatteriesthatexceedserviceorshelflife.Condemnedbatteries

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maybeusedfortrainingordisposedofinaccordancewithTO00-25-213-WA-1.5.6BATTERYSERVICELIFETEST.5.6.1BatteryTestUsingMultimeterand

a130Ohm1WattResister.NOTE

Iftestindicatesa

goodbattery,reinstallinsurvivalradio.Ifitindicatesabadbattery,replace

itwithanewbatterywhichhasbeentestedgood.

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a.Removebatteryfromradiosetandinspectforevidenceofswelling,chipped/crackedsurface,andmoisture.Ifanyoftheseconditionsare

presentthebatterywillbecondemned.TheBA-5368/Ubatteryhasashelflifeof

60months(5years)fromthedateofmanufactureandaninstalledservice-life

of36months(3years).Condemnandreplacebatteriesthat

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exceedserviceorshelflife.CondemnedbatteriesmaybeusedfortrainingordisposedofinaccordancewithTO00-25-213-WA-1.NOTE

Any

oneWatt125to135Ohmresistermaybesubstitutedinplaceof

thoseNSNslistedbelowaslongasitmeetsthesamecriteria.

(1)BA-5368/UBatterytestforuseLi/MnO2battery.The

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purposetestistoplaceloadonthebatterythatsimulatesbatterytransmittinginthebeaconmode(approximately100milliampload).(2)Anyone

watt125to135ohmresistermaybeusedinplaceofthose

NSNslistedbelow:1WattcarRCR32G131JM5905-00-455-2301bon:5905-00-1215905-00-520-53889927

1WattWireRWR81N1300FR5905-01-073-2919wound:

1Watt

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WireRWR81S1300FR5905-00-152-7565wound:

b.Obtainaonewatt130ohmresisterwithextenderleadandmultimeter.5.7SERVICELIFETEST.

TheAN/PRC-90seriesRadiousesaLithiumManganeseDioxidebatteryasitspower

source.Donotshortcircuit,crush,puncture,mutilate,ordisassemblebatteries.The

BA-5368/UbatterycontainsLithiumManganesedioxidemixture.Underconditionsof

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NOTE

Newbatteriesfailingtomeettheminimumfirsttimetestvoltagerequirementswillbeprocessedunderproductqualitydeficiency

report(PQDR)andwillberetaineduntilreceiptofdispositioninstructions.Lithium

batteriesshallbetestedonlyafterallowingtostandatambient(shop)temperature

for4hoursafterremovalfromradio.Newbatteriesshall

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notbetestediftheyareknowntohavenotbeenstoredatambient(shop)temperatureforatleast4hours.Voltagechecks

shallnotexceedone10secondtestcheckper1hourtimeperiod.

Ifretestisnecessarytoobtainthevoltagereading,aminimumof1

hourisrequiredtoallowvoltagereturn.5.8BATTERYTEST

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(BA-5368/U).Batteryisapotentialexplosivehazard.Wearfaceshieldorgoggleswhenhandlingbattery.Wearrubbergloveswhenhandlingthebatterytoprevent

skincontamination.BA-5368/UBatterycontainslithium.Contactwithliquidorvaporcancause

skinirritation,headache,andfatigue.Ifliquidcontactsskinoreyes,washaffected

areawithwaterandgetimmediatemedicalattention.Resistorcan

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becomehotandcauseburnsduringtest.

a.OnlyonetestprocedureisauthorizedforuseinvoltagetestforBA-5368/Uand

BA-5123/Ubattery(s).Supportequipmentrequired(SeeChapter3)Multimeterand130OhmResistor.

NOTE

Sincebatteryperformancevarieswithtemperature,thebatterytestshould

beperformedatroomtemperature(25C,77F).Ifthetest

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isperformedatalowertemperature,agoodbatterymaynotpassthetest.

b.UsingMultimeter,measureresistanceof130Ohm

Resistor.Resistancemustbebetween127and133Ohms.c.ConnectResistoracross

Multimetertestleads.d.Whileobservingbatterypolarity,connecttestleadstobattery

for10seconds.(1)(BA-1568/U)Batteryvoltageshouldnotdrop

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below12.0VDC.Ifvoltagedropsbelowspecifiedvalue,condemnbatteryperlocalprocedures.TO31R2-2PR-101

(2)(BA-5368/U)Batteryvoltageshouldnot

dropbelow10VDC.Ifvoltagedropsbelowspecifiedvalue,condemnbatteryper

localprocedures.e.PlaceinspectiondecalonRadioSetasshowninFigure

5-1,andenterdateoftest,typeofbattery,and

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dateofmanufactureondecal.5.9BATTERYTEST(BA-5123/U).Ifonebatteryisweak,excessiveheatingmayresultandtheweakbatterymayexplode.

Batteryisapotentialexplosivehazard.Wearfaceshieldorgoggleswhenhandling

battery.Wearrubbergloveswhenhandlingthebatterytopreventskincontamination.BA-5123/U

Batterycontainslithium.Ifliquidcontactsskinoreyes,wash

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affectedareawithwaterandgetimmediatemedicalattention.

5.9.1WhenusingaccessorybatteryadapterandfourBA-5123/U(commercialtypeCR-123)

batteriesinsteadoftheBA-5368/Ubattery,allfourbatteriesmustbetestedand

checkgood.Resistorcanbecomehotandcauseburnsduringtest.SupportEquipment

Required(SeeChapter2)ZTSMultibatterytesterora

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Multimeterand10OhmResistor.NOTE

Sincebatteryperformancevarieswithtemperature,thebatterytestshouldbeperformedatroomtemperature(25C,

77F).Ifthetestisperformedatalowertemperature,agoodbattery

maynotpassthetest.

a.UsingMultimeter,measureresistanceof

10OhmResistor.Resistancemustbebetween9.8and10.2

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Ohms.b.ConnectResistoracrossMultimetertestleads.c.Whileobservingbatterypolarity,connecttestleadstobatteryfor10seconds.Batteryvoltageshould

notdropbelow2.95VDC.Ifvoltagedropsbelowspecifiedvalue,condemnbattery

perlocalprocedures.d.PlaceinspectiondecalonRadioSetasshownin

Figure5-1andenterdateoftestandtypeof

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batteryondecal.NOTE

Aftermaintenance,batterieswillnotbeinstalledinradiosunlesstheradioisrequiredtofillanimmediate

operationalrequirement.Repairedradiosleavingthedepotwillnotbeshippedwitha

batteryinstalledintheradioorplacedintheshippingcontainer.

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Asmallinspectionlabel,willbeusedtoindicatereplacementdate,lastinspectiondate,andbatterytype.Decalcanbe

locallyreproduce

onscotchcaltypepressuresensitivematerial.ThemeasurementsofthisLabelare:

1inchHX11/2inchesL.SeeFigure5-1.

5.11INSPECTIONRECORD.

Asmallinspectionlabelwillbeusedtoindicatebattery

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mandatoryreplacementdateasstampedonbatteryandthedateofeachradioinspection.ObtainlocalfabricationusingScotchCalMaterialorsuitablesubstitute.

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TO31R2-2PR-101

CHAPTER6ORGANIZATIONALMAINTENANCE

6.1 GENERAL.ThepurposeofthisChapteristoinformorganizationalmaintenancepersonnelhow

toperformvisual/mechanicalinspectionsoftheAN/PRC-90andtotesttheoperationof

theradio.Ifotherdeficienciesdemandingrepair,replacement,ordisassemblyofcomponentsother

thanthebattery,earphone,orantennaarediscoveredasa

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asapreflightcheckout,butresultsofpreflighttestsshallnotberecorded.LifesupportshopswhichhaveaTS-24Btestsetwilltest

survivalradiosforserviceabilityinaccordancewithParagraph7.3.Whenaquestionableradio

isidentifiedbythistesting,suspectedradiowillberoutedtotheavionics

shopforverificationandmaintenanceactionasrequired.

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manorlifesupportshoppriortoimmediateissue.NOTEDonotaccomplishconcurrentlywith120dayfieldlevelinspection.NOTEThisinspectionwill

alsobeperformedattheorganizationallevelwhentheTS-24Btestsetbused.

1.Inspecttheexterioroftheradiosetfordamage,cleanliness,andproper

operationofallcontrols.Checkthatthefollowingconditionsare

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TO31R2-2PR-101

Table6-1.PeriodicInspectionand/orTest-Continued

InspectionorTestPreflightOrganizational120DaysField2.3.

4.5.6.7.8.9.b.Functionswitchturnswithproperdetent

action,withoutbinding.c.Antennaiscleanandmaybeextendedandstowed-without

binding.Rubbercoverisnotcrackedorbroken.Antennatip

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issecure.d.InspectrubbercoversonPUSHTOTALKandMCWbuttonsforcracksandbreaks,andnotecoversarefirmlyattachedto

sealthebuttons.Depressbothbuttons;buttonsmustmovefreelyandspring-returnto

originalpositions.e.Inspectwrist-strapwebbingforfrayingordeterioration.f.Inspecthalf-wave

antennaretainingbandforcracks,deterioration,oranoutstretchedcondition.

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PerformParagraph5.4.Removethebatterywellcapinspectcapforsealingwasherorspringdamage.Inspectbatterywellforsignsofcorrosionandcleanliness

ofsurfacesandcontacts.Installbatteryandreinstallbatterywellcap.Turnradio

oninsureaudiblenoisecanbeheardonbothchannelsfromthelisten

speaker.Turnradiooff,checkinspectiondecaltoinsuredate

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iscurrent.PerformquickoperationalcheckinaccordancewithParagraph2.7.Maybeaccomplishedconcurrentlywithstep6.Performtheoperationalcheckinaccordance

withParagraph6.3throughParagraph6.13.Performthepreliminaryoperationalcheckinaccordance

withParagraph7.2orwithTS24BradiotestsetinaccordancewithParagraph

7.3.Antennatip.PerformParagraph7.14procedure.Ensureallback

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platescrewsareinstalledandtight.Loosescrewswillbetightenedasfollows:Rotatewithscrewdriveruntilscrewissnugagainstbackplatethen

rotate1/4to1/2turn.--1c.--------3.4.------

----1b.1c.1d.1e.1f.2.----5.6.------

1b.1c.1d.1e.1f.2.--------7.

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8.9.

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orimpendingtroubleintheAN/PRC-90.Performtheseoperationalchecksinthefollowingmanner:

6.4BATTERYCHECK.TestbatteryperParagraph5.5.

6.5TRANSMITTERANDRECEIVERTESTSET-UP.ThefollowingtestsuseRadio

TestSetAN/PRM-32/TS-20/PRM-32AandasecondradiosetAN/PRC-90tocheckthe

operationalstatusofradiosetAN/PRC-90.Theproceduresaspresented

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assumethatthesecondradiosetisknowntobeoperatingproperly.Itispossible,however,tocheckoutbothradiosetssimultaneouslyusingthese

procedures.Todothis,firstperformthetransmitterchecks(Paragraph6.4throughParagraph

6.10)onbothradiosets.Thereceiverandearphonechecks(Paragraph6.11through

Paragraph6.13)maythenbeperformed.

Forthe

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transmittertests,connectthetestequipmentasfollows(seeFigure6-1).WhenusingTS-20/PRM-32Aturnthetestsetswitchto243/282.8MHz.

a.Verifythatbothradiosetshavegoodbatteriesinstalled.b.Remove

antennasfrombothradiosetsusingantennawrench,asinParagraph6.14.See

Figure6-1.NOTE

Inspectrubberportionofsealing

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washerforcutsanddeterioration.Replacedamagedwasheraccordingly.Useextremecarethatyoudonotlosesealingwasherfromantenna.

c.

Connecttestcablesoftestsettoradiosetantennajacks,testpoint

1,asshowninFigure6-1.Theradiosetundertestisconnected

tothetransmittercable.Carefullyavoidcrossthreadingwhenscrewing

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test-setcableconnectorstoradiosethousing.Seatconnectorsfinger-tightonly.TO31R2-2PR-101

6.6GUARDCHANNELBEACONTRANSMITTERCHECK.Performthe

followingstepstochecktheoperationoftheguardchannelbeacontransmitterunder

operatingload.