McIntosh MR 500 User manual

Contents
SERVICECONTRACTINFORMATION1
INTRODUCTION2
INSTALLATION3,4
BACKPANELCONNECTIONS
ANDCONTROLS5,6
USINGTHEFRONTPANEL
CONTROLS7,8
HOWTHECIRCUITSWORK9, 10
PERFORMANCELIMITS11
PERFORMANCECHARTS.. . .12,13
BLOCKDIAGRAM14
FMSTATIONLOG15
TheMclntoshcompactFamily
TheMR500DigitalFMTunercomplementstheper-
formanceandappearanceofallMclntoshproducts.It
isspecificallydesignedtomatchtheindustry's
leadingcompacts— theMclntoshMC502PowerAm-
plifierandtheMclntoshC 504Preamplifier.Separate,
flexibileMclntoshqualitycomponentsthatarepar-
ticularlyusefulwherespaceislimited.
1
MR500
DIGITAL
FM
TUNER
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TheMR500FMTunerisdesignedto
performtoitsspecificationsformany
years.Ifyouhaveanyquestions, please
contact:
CUSTOMERSERVICE
MclntoshLaboratoryInc.
2ChambersStreet
Binghamton,NewYork13903-9990
Phone:[phone]
TakeAdvantageof3 yearsof
ContractService...
FillintheApplicationNOW.
MclNTOSHTHREEYEARSERVICECONTRACT
AnapplicationforA THREEYEARSERVICECONTRACTisincludedwiththismanual.
Thetermsofthecontractare:
1.Mclntoshwillprovideallparts,materials
andlaborneededtoreturnthemeasured
performanceoftheinstrumenttothe
originalperformancelimits.Because
batterylifeisdependentonconditions
overwhichMclntoshhasnocontrol,
theyarenotcoveredundertheservice
contract,norisanyshippingcosttoand
fromtheauthorizedserviceagencyor
thefactory.
2.AnyMclntoshauthorizedserviceagency
willrepairMclntoshinstrumentsatnor-
malservicerates.Toreceiveservice
underthetermsoftheSERVICECON-
TRACT,theSERVICECONTRACTCER-
TIFICATEmustbepresentedwhenthe
instrumentistakentotheserviceagency.
3.Alwayshaveservicedonebya
Mclntoshauthorizedserviceagency.If
theinstrumentismodifiedordamaged
asa resultofunauthorizedrepair,the
SERVICECONTRACTwillbecancelled.
Damagebyimproperuseormishandl-
ingisnotcoveredbytheSERVICE
CONTRACT.
4.TheSERVICECONTRACTisissuedto
youastheoriginalpurchaser.Topro-
tectyoufrommisrepresentation,this
contractcannotbetransferredtoa se-
condowner.
5.ToreceivetheSERVICECONTRACT,
yourpurchasemustbemadefroma
Mclntoshfranchiseddealer.
6.Yourcompletelyfilledinapplicationfor
theSERVICECONTRACTmustbepost-
markedwithin30daysofthedateof
purchaseoftheinstrument.
7.ToreceivetheSERVICECONTRACT,all
informationontheapplicationmustbe
filledin.TheSERVICECONTRACTwill
beissuedwhenthecompletelyfilledin
applicationisreceivedbyMclntosh
LaboratoryIncorporatedinBinghamton,
NewYork.
8.UnitsinoperationoutsidetheUnited
StatesandCanadaarenotcoveredby
theMclntoshServiceContract,ir-
respectiveoftheplaceofpurchase.Nor
areunitsacquiredoutsidetheU.S.A.
andCanada,thepurchasersofwhich
shouldconsultwiththeirdealerto
ascertainwhat,ifany,servicecontract
orwarrantymaybeavailablelocally.
Copyright1983(C)byMclntoshLaboratoryInc.
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Installation
ThePANLOCsystemofinstallingequipment
convenientlyandsecurelyisa productofMclntosh
research.BydepressingthetwoPANLOCbuttonson
thefrontpanel,theinstrumentcanbeeitherlocked
firmlyinplaceoritcanbeunlockedsothatthe
chassiscanslideforward,givingyoueasyaccessto
thetopandrearpanels.
Thetrouble-freelifeofanelectronicinstrumentis
greatlyextendedbyprovidingsufficientventilationto
preventthebuild-upofhighinternaltemperaturesthat
causedeteriorationofcomponentparts.Youshouldal-
lowenoughclearancesothatcoolaircanenteratthe
bottomofthecabinetandbeventedfromthetop.With
adequateventilationtheinstrumentcanbemountedin
anyposition.Therecommendedminimumspacefor
adequateventilationis17inches(43.2cm)wide,and4
1/2inches(11.4cm)high,15inches(38.1cm)deep.
Toinstalltheinstrumentina Mclntoshcabinet,
followtheinstructionsthatareenclosedwiththe
cabinet.Foranyothertypeofinstallationfollow
theseinstructions:
1.Unpackfromcarton
OpenthecartonandremovethePANLOCbrack-
ets,hardwarepackage,andmountingtemplatefrom
thecarton.RemovetheMR500fromitsplasticbag
andplaceitupsidedownontheshippingpallet;
thenunscrewthefourplasticfeetfromthebottom
ofthechassis.
2.Markthecabinetpanel
Placethemountingtemplateinthepositionon
thecabinetpanelwheretheinstrumentistobein-
stalled,andtapeitinplace.Thebrokenlinesthat
representtheoutlineoftherectangularcutoutalso
representtheoutsidedimensionsofthechassis.
Makesuretheselinesclearshelves,partitions,or
anyequipment.Withthetemplateinplace,first
markthesixA andB holesandthefoursmallholes
thatlocatethecornersofthecutout.Then,jointhe
fourcornermarkingswithpencillines,usingthe
edgeofthetemplateasa straigtedge.
3.DrillHoles
Usea drillwitha 3/16inch(5mm)bitheldperpen-
diculartothepanelanddrillthesixA andB holes.
Then,usinga drillbitslightlylargerthanthetipof
yoursawblade,drilloneholeateachoftwo
diagonallyoppositecorners.Theholesshouldbare-
lytouchtheinsideedgeofthepenciledoutline.
Beforetakingthenextstep,makesurethatthesixA
andB holeshavebeendrilled.
4.SawthePanelCutout
Sawcarefullyontheinsideofthepenciledlines.
Firstmakethetwolongcutsandthenthetwoshort
cuts.Aftertherectangularopeninghasbeencutout,
usea filetosquarethecornersandsmoothany
irregularitiesinthecutedges.
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5.InstalltheMountingStrips
Inthehardwarepackageyouwillfindtwomount-
ingstripsandtwosetsofmachinescrews.For
panelsthatarelessthan1/2inch(12.7mm)thick,
usethe3/4inch(19.1mm)screws;forpanelsthatare
morethan1/2inch(12.7mm)thick,usethe1 1/4inch
(31,8mm)screws.
Startingattheright-handsideofthepanel,insert
ascrewofproperlengthintothecenterholeinthe
panel,markedB onthetemplate.Onthebackofthe
panel,aligna mountingstripwiththeholesinthe
panelandtightenthescrewinthecenterholeuntil
thescrewheadispulledslightlyintothewood.
Repeatthisproceduretoattachthemounting
striptotheleftsideofthepanel.
6.AttachthePANLOCBrackets
UsetwoscrewsoftheproperlengthintheA holes
oneachside,attachthePANLOCbracketstothe
cabinetpanel;theshortflangeismountedagainst
thefront(face)ofthecabinetpanel.Thescrews
passthroughthePANLOCbracketflange,the
cabinetpanel,andthenthroughthemountingstrips
previouslymounted.
7.InstalltheInstrument
GuidetheACpowercordthroughthepanelopen-
ingtothebackofthecabinet.Then,slidetheinstru-
mentintotheopening,carefully,sothattherailson
thebottomofeachsideofthechassisengagethe
tracksonthemountingbrackets.Continuetoslide
theinstrumentintothecabinetuntilitisstoppedby
theadjustpositionlatches.Pressthelatchesin-
ward,thispermitstheinstrumenttoslideintothe
cabinetuntilitsfrontpanelisflushwiththecabinet
panel.DepressthePANLOCbuttonsatthelowerleft
andrightcornersoftheinstrumentpaneltolockthe
unitfirmlyinthecabinet.DepressingthePANLOC
buttonsagainwillunlocktheinstrumentsothatit
canslidetotheadjustposition;ifyoupressinward
ontheadjustpositionlatchesthenyoucanremove
theinstrumentfromthecabinet.
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BackPanelConnectionsandControls
Useofthebackpanelconnectionsandcontrols
willbedescribedfromrighttoleftwhenlookingat
thebackpanel.
MANUALAFL
AutomaticFrequencyLock(AFL)isa Mclntosh
designwhichassuresthatthestationremainsideal-
lytunedregardlessofanyinfluencesthatmight
causethestationtodrift.BecausetheAFLcircuit
doesnotaffectthehighqualityperformanceofthe
MR500,theswitchshouldbeusedintheNORMAL
position.Theremaybeoccasionswhenitwouldbe
desirabletodeactivatetheAFLcircuitformanual
tuning.WiththeMANUALAFLswitchintheOUT
position,andwhenusingthetuningknob,theAFL
circuitisdisabled.TheAFLcircuitisalwaysactive
whentheSCANtuningandthefeathertouchpreset
stationselectionpushbuttonsareused.
AUDIOOUTPUTS
UsetheFIXEDOUTPUTjacksontherearpanelto
connecttheMR500toa stereocontrolpreamplifier
orotherequipmentwhichhasitsownvolumecon-
trol.ThepositionoftheVOLUMEcontroldoesnot
affecttheloudnessofthetunerattheFIXEDOUT-
PUTjacks.Theoutputlevelis1 voltfor100%FM
modulation.
UsetheVARIABLEOUTPUTjackstoconnectto
equipmentsuchasa poweramplifierora tape
recorderwherecontrolofthevolumeistobeatthe
tuner.WiththeVOLUMEcontrolturnedcompletely
clockwise,theoutputattheVARIABLEOUTPUT
jacksis2.5voltsfor100%FMmodulation.Thereis
nodifferenceinthesignalqualityateitherofthe
pairsofoutputjacks;and,bothpairsmaybeused
simultaneously.Theoutputimpedanceisverylow
sothatlongaudiocablescanbeusedwithouta loss
ofhighfrequenciesduetocablecapacity.
SCOPE
TheverticalandhorizontalSCOPEjacksarepro-
videdtoconnecttoa maximumperformancein-
dicatororanoscilloscopewhichcanthenindicate
FMmultipathandsignalstrength.Connectthever-
ticaljacktotheverticalinputoftheindicatorand
thehorizontaljacktothehorizontalinput.
REMOTESCAN
TheREMOTESCANjackprovidesaninputforthe
cablepushbuttonassemblysuppliedwiththe
MR500.PlugthecableintotheREMOTESCANjack
toprovideSCANtuningata convenientlocation
remotefromthetuner.IfREMOTESCANtuningis
notused,leavethejackfreeofanyconnection.
CONNECTINGANFMANTENNA
Oneofthreeantennasystemscanbeused:(1)an
outdoorFMantenna,or(2)a VHF-TVantenna,or(3)
theindoordipolesupplied.
Anoutdoorantennaisrecommendedforoptimum
performanceinallareas.Forbestresultsinfringe
(outlying)areas,usea highlydirectionalFMantenna
inconjunctionwitha rotator.Iftheantennausesa
300ohmdownlead,connectittotheANTENNA
300ohm FM pushconnectors.
AVHF-TVantennadesignedforbothFMandTV
receptioncanbeeffective.Connectthedownlead
fromtheVHF-TVantennatotheANTENNA30012FM
pushconnectors.
Thecoaxialcableofanunbalanced75ohmanten-
naconnectstotherearpanelANTENNA75ohmFM
typeF coaxialconnector.
Suppliedwiththetunerisa flexiblefoldeddipole
antennaforuseinurbanorhighstrengthsignal
areas.ConnectittotheANTENNA300ohmFMpush
connector.Theflexibilityofthetwinflatwire
assemblypermitsittobeplacedundera rug,tacked
behindthestereoorplacedinanyotherconvenient
location.Insomecases,itmaybenecessaryto
"position"theantennaforbestsignalreception.Do
thisbeforeitispermanentlylocated.Avoidlocating
theantennanexttootherwiresormetalobjects.Any
indoorantennamaybeineffectiveinhouseshaving
metalsidingormetalfoilinsulation.
120VACOUTLET
Providesa 120voltACpoweroutletwithupto300
wattsavailableforadditionalequipmentthathasits
ownACpowerswitch.Theoutletisnotfused.
ACPOWERCORD
ConnecttheACpowercordtoa 120volt,50to60
Hzpowerlinereceptacle.Thepowerusedbythe
MR500is15watts.
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UsingtheFrontPanelControls
OnthefrontpaneloftheMR500thereare:volume
controlwithtuneron/offACpowerswitch,6 momen-
taryfeathertouchpushbuttonsforselectingpreset
stations,a jackforheadphonelistening,1 on/off
pushbuttonforbetweenstationnoisemuting,4
momentarytuningassistancefeathertouchpush
buttons,a digitalfrequencydisplay,6 presetstation
indicators,anallsolidstatetuningindicatorandthe
manualtuningknobandindicator.
VOLUMECONTROLWITHACPOWERSWITCH
TheVOLUMEcontrolhasbeenprecisiontracked
troughoutthelisteningrange(0to-65dB)forac-
curatestereobalance.TheACpowerswitchispart
oftheVOLUMEcontrol.Theoutputlevelofthe
VARIABLEOUTPUTjacksandthefrontpanelHEAD-
PHONEjackiscontrolledbytheVOLUMEcontrol.
TheFIXEDOUTPUTjacksarenotaffectedbythe
positionoftheVOLUMEcontrolexceptwhenthe
VOLUMEcontrolisturnedfullycounterclockwise
theACpoweristurnedoff.
PRESETSTATIONSELECTING
'FEATHERTOUCH'PUSHBUTTONS
Amomentarypressononeofthepushbuttons
marked1 thru6 willrecallfromtheelectronic
memorythepre-setstationassignedtothatpush
button,thecorrespondingindicatorunderthedigital
frequencydisplaywilllightandthestationwillbe
tunedtotheexactcenterofthechannel.AFListhen
appliedandprecisetuningismaintained.
HEADPHONEJACK
AHEADPHONEjackisprovidedtodrivelowim-
pedancedynamicheadphonesfromaninternal
stereopoweramplifier.
ENTER
TheENTERpushbuttonandoneofthesixmomen-
aryfeathertouchpushbuttonsareusedtoinsertinto
theelectronicmemorythedesiredtunedstation.Sta-
tionscanbeselectedforinsertionintheelectronic
memorybyuseofeitherthemanualtuningknobor
SCANtuning.Toentera stationinthememory,tuneto
thedesiredstationwiththemanualtuningknob,orthe
SCANtuning.Then,whilepressingtheENTERpush
buttonpressoneoftheupperrow,numberedpushbut-
tons.Releasebothpushbuttonsandthestationtuning
isrecordedintheelectronicmemoryforinstantaneous
recall.Becausethememoryisretainedwhenthe
MR500isturnedoff,uponturnonitwilloperateinthe
samemodeofoperationandstationtuningaswhen
turnedoff.
THEELECTRONICMEMORY
CHARGINGBATTERYPOWERSUPPLY
Averylonglife,rechargeablebatterypowersupp-
lyprovidestheenergyfortheelectronicmemory
whenthetuneristurnedoff.Whenthetunerisfirst
connecteditiswisetoassumethatthebatteries
havenotbeencharged.Thechargerateisdictated
bythe'on'timeofthetuner.Tobringthebatteriesto
fullcharge,operatethetunerfortwentyfourcon-
tinuoushours.Whenfullycharged,thetunerwillre-
taintheprogrammedinstructionsformorethansix
monthswiththetunerturnedoff.Afterthebatteries
arefullycharged,usingthetunerforapproximately
onehourperweek,willmaintainthebatteriesina
fullychargedstate.Batterylifeisdependenton
usage,storage,temperatureandtime.
Donotattempttoremovethebatteriesfromthe
MR500.Batteryreplacementshouldonlybedoneat
Mclntoshauthorizedserviceagencies.
MUTE
WiththeMUTEpushbuttonpressedtotheIN
position,weaknoisystationsandbetweenstation
noisesaresurpressedwhenusingthemanualtun-
ingknob.Mutingcircuitsarenotactivewiththe
MUTEpushbuttonout.Mutingisalwaysactive
whenusingthepresetstationselectorsandwhen
SCANtuning.
MANUAL
AmomentarypressoftheMANUALfeathertouch
pushbuttonwillactivatethetuningknobasin-
dicatedbythelightedarrowabovetheknob.Rotate
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thetuningknobuntilthefrequencyofthedesired
stationshowsonthedigitalfrequencydisplay.
Astationiscorrectlytunedwhenthecenterarrow
indicatoratthebottomofthetuningindicatoril-
luminates.Oneachsideofthecenterarrowarear-
rowsmarked+ and-,oneofwhichwilllightasa
stationisapproachedtoindicatetuningabove( + )
orbelow(-)thecenterofthestation.Whenthe
centerarrowlights,thestationiscenterchannel
tuned,theFMAFL(automaticfrequencylock)circuit
isactivatedandthetunerislockedtotheFMsta-
tion.MclntoshAFLwillgivethebestFMreception
withlowestbackgroundnoise,lowestdistortionand
beststereoseparation.
BecauseofthelockingactionoftheAFLcircuit,
thetuningknobcanbeturned,mechanically,slight-
lyawayfromthefrequencyofthestationwithout
detuning.Thismakestuningveryeasybutcan
causethetunertolosethestationwhenpoweris
turnedoffandonagain.Topreventthis,stoprota-
tionofthetuningknobassoonasthecenterarrow
islighted.
AmomentarypressoneithertheSCANorpreset
stationpushbuttonsdeactivatesthemanualtuning
knobandactivatesthetuningmethodselected.
SCAN
Thetunerwillautomaticallypreciselytunethe
nextstationupordownthespectrumdepending
whichSCANpushbuttonispressed.Thearrow
abovethepushbuttonindicatesthedirectionofthe
scan.Whentheremotescancableis insertedin the
rearpanelreceptacle,a momentarypressofthe
pushbuttonontheendoftheremotescancablewill
activatethetunerscan-upcircuits.
TUNINGINDICATOR
Accuracyoftuningandsignalstrengthisin-
dicatedbythe14LEDtuningindicator.Atthetopis
abarwhich,whenilluminated,indicatesthatthe
tunedstationistransmittinginstereo(MPX).The
verticalcolumnof10dotsshowstherelativesignal
strengthforthereceivedstation.Thegreaterthe
numberofilluminateddotsthegreaterthestation's
signalstrength.
Thethreearrowsatthebottomoftheindicator
showsabove(+),below(-)orexactcenterchannel
tuning.A correctlytunedFMstationwillhaveonly
thecenterverticalpointingarrowlighted.
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HowtheCircuitsWork
TUNINGSYSTEM
TodaysFMelectronictuningsystemscan
generallybeclassifiedaseithera PhaseLocked
Loop(PLL)SynthesizerSystemorVoltageSyn-
thesizer,SignalLockedLoopSystem.
MclntoshhasselectedtheVoltageSynthesizer,a
SignalLockedLoop(SLL)Systemwhichlocksthe
MR500totheincomingsignaloftheFMstation.
Withthetunertunedtothestationfrequencyand
thecorrectionvoltagebeinggeneratedbythedetec-
tor"zero"crossing,allpartsofthetuner,mixer,
localosc.,IF,etc.areinsidethetuningloopandac-
curatetuningisassured.Aslongasthestation
transmitswithinthetuningrangeoftheMR500,
regardlessoffrequency,theSLLsystemwilllockon
tothestationandremaincenterchanneltuned.
Incontrast,inthePLLsystem,thelocaloscillator
frequencyiscomparedtoa referencewithinthe
tuner,usuallya crystalcontrolledoscillator.A com-
parisoncircuitgeneratesa correctionvoltageto
holdthelocaloscillatortoanexactmultipleofthe
referenceoscillator.Thefrequencyofthereference
oscillatormustbeequaltothestationchannelspac-
ing(200kHzintheUnitedStates)inordertocoverall
theFMchannels.Tuningisaccomplishedindis-
cretestepswhichmakesitimpossibletotuneto
frequenciesbetweenchannels.InareaswhereFM
programsaredistributedbycableornon-standard
frequencies,andinotherpartsoftheworldwhere
stationsmaybeassignedtofrequenciesotherthan
thosestandardintheUnitedStates,properrecep-
tionisnotpossible.AnotherlimitofthePLLsystem
isthatthesystemcangenerateharmonicsandspur-
iousresponsesinthedividerchainandfre-
quency/phasecomparator.Theseunwantedsignals
willaddnoiseinterferencetothereceivedstation.
ThesuperiorityoftheSignalLockedLoopSystem
madeittheobviouschoiceforthedemandingper-
formancerequiredoftheMR500.
OntheMR500,threemodesoftuningareprovid-
ed:MANUAL,SCANandPRESET.
IntheMANUALmodea regulatedtemperature
compensatedreferencevoltageisfedtothetuning
potentiometer.A portionofthisvoltageasselected
bythepositionofthepotentiometerisfedtothe
controllerintegratedcircuit(IC).Itisthenamplified,
filteredandappliedtothetuningvaractors.Proper
tuningisalwaysguaranteedsincetheoutputofthe
FMdetectoratzerocrossingisreferencedto4.75
voltsandisfedtotheS curveinputofthecontroller
througha DCamplifier.Ifa deviationfromthe4.75
voltsiscausedbya shiftintuningorstationdrift,
thecontrollergeneratesa correctionvoltageand
combinesitwiththevoltagebeingfedtothetuning
varactorstomaintainpropertuning.
Whena SCANfeathertouchpushbuttonispress-
eda DCramptuningvoltageisgenerated,risingin
voltageforSCANup,decayingforSCANdown.The
rampcontinuesuntilthezerocrossingofthedetec-
torS curveissensedattheinputofthecontroller.
Thetuningvoltagerampstopsandisthenmaintain-
edwithanynecessarycorrectionvoltageadded.
Thetuningvoltagepresentattheoutputofthe
controllermaybeputintoanyofthesixmemory
pushbuttonlocationsatanytime.Pressingthe
ENTERbuttoncausesanAnalogtoDigitalconver-
sionofthetuningvoltagetotakeplace.Then,while
stillholdingtheENTERbutton,pressingoneofthe
sixnumberedbuttonsstoresthetuninginformation,
indigitalform,withinthecontrolICmemory.
Amomentarypressofa presetstationpushbut-
tonwillinstantaneouslyrecallthestationfromthe
digitalmemory.Thetuningvoltageretainedinthe
electronicmemoryisdeliveredtotheoutputofthe
controller.Toinsurepropertuninga searchand
fetchoperationtakesplace.Thetuningvoltageis
movedplusandminusitsnominalvalueinincreas-
ingstepsuntilthecorrectstationzerocrossing
signalisreceivedfromthedetector.Thestationfre-
quencyiscapturedandonceagainthetuning
voltageismaintainedwithanynecessarycorrection
added.Eachtimea presetpushbuttonispressed,a
mutepulsesuppressesanynoisethatmayoccur
duringthetuningprocess.
DuringtheSCANmode,anoutputfromthecon-
trollerisusedtolowerthetunersensitivitytopre-
ventweaknoisystationsfrombeingheard.
Anautomaticallyrechargedlonglifenickelcad-
miumbatteryprovidesthenecessaryvoltagetothe
memorytoretainitsinstructionswhenACpowerto
thetuneristurnedoff.Thelastmodeofoperation
usedbeforeturnoffandthestationfrequencyarere-
tainedinthememory.Whenthepoweristurnedon
thetunerwillautomaticallyreturntothemodeof
operationandfrequencylastused.
FMTUNER
Antennaconnectionsfor300ohmtwinleadand
75ohmcoaxialcableareprovidedontherearpanel.
ThenormalinputimpedanceoftheFM-RFsectionis
75ohms.A Mclntoshdesignedandmanufacturedin-
ternalbalunmatchingtransformerprovidesa per-
fectmatchfora 300ohmantenna.Connectionsfor
thetwinleadaremadewithpushtypeterminalsand
atypeF connectorisprovidedforthecoaxialcon-
nection.
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Followingtheantennamatchingcircuitisa RF
tunerofexceptionalperformance.Itusesa DMOS-
FETRFamplifier,a doublebalancedmixer,andcir-
cuitsthataretunedbya seriesparallelconnection
offourmatchedvaractordiodes,allofwhichpro-
ducehighspuriousrejectionandgreatsensitivity.
Thiscircuitryandthehightuningvoltage(5-25V)
eliminatesRFintermodulationdistortioncausedby
diodenon-linearities.
TheFMIFsectionuses3 transistors,3 linear
phasepiezoelectricfilters,andoneintegratedcir-
cuit.Theycombinetoprovideover120dBofgainand
aselectivitygreaterthan65dB.Limiting,muting,
signalstrengthdrive,andFMdetectionareallfunc-
tionsoftheintegratedcircuit.
Aphaselockedloop(PLL)stereodecoderin-
tegratedcircuitistheheartofthemultiplexsection.
Ithasa highsignaltonoiseratio,lowdistortion,
highchannelseparation,andhighSCArejection.
ThePLLMPXICeliminatesinductorstominimize
drift,providesintegrallampdrivingcapabilitytoin-
dicatethepresenceofthe19kHzpilot,andhastran-
sientfreemono/stereoswitching.
FollowingthePLLMPXdecoderisaJ-FETswitch-
edfiltercircuitthatreduces'outofphasenoise'
whentheMR500istunedtoaweakstereostation.A
LCtunednotchfilterisusedtopreventtaperecorder
biasinterference.TheLCfilterisdrivenfromthe
MPXoutputamplifierandisterminatedbythe
followingfixedoutputoperationalamplifier.This
providesthenecessaryfilterinputandoutputim-
pedancesforproperphaseresponse.A lowpower
amplifierwithlessthan.01%harmonicdistortion
drivesheadphonesoutputandthevariableoutput
jacks.
TheMR500hastransientfreeturnon/off
characteristics.A lightdependentresistor,whose
lightsourceistimecontrolled,connectsthetuner
outputsapproximatelytwosecondsafterthepower
isturnedontoallowallcircuitstostabilizebefore
soundcanbeheard.
FREQUENCYCOUNTER
ThefrequencycounterconsistsoftwoIC's.Oneis
anEmitterCoupledLogic(ECL)buffercircuitand
divideby100prescaler.Theotherisa C-MOSLSIIC
thatcontainsthereferenceoscillator,various
dividers,latches,andLEDsegmentdriversforthe
display.TheLEDdisplaydoesnotgenerateRFin-
terferencebecauseitisstatic,notmultiplexed.An
adjustableIFoffsetisprovidedsothatthedisplay
readsthetunedfrequencyaccuratelyforthefull
spanofIFfiltertolerances.
POWERSUPPLY
The+ 15,- 15,and+5 voltsuppliesuseICthree
terminalregulators,whilethe+33voltsupplyuses
azenerdioderegulator.Thisinsuresproperopera-
tionofthetunerevenduringperiodsoflowACline
voltages.
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PerformanceLimits
Performancelimitsarethemaximumdeviation
fromperfectionpermittedfora Mclntoshinstru-
ment.Wepromiseyouthatwhenyoupurchasea
newMR500froma Mclntoshfranchiseddealer,it
willbecapableoforcanbemadecapableofperfor-
manceatorexceedingtheselimitsoryoucanreturn
theunitandgetyourmoneyback.Mclntoshisthe
onlymanufacturerthatmakesthisstatement.
USABLESENSITIVITY
13dBF,whichis2.5µVacross300ohmor1.25µV
across 75ohm
50dBQUIETINGSENSITIVITY
Mono- 16.8dBF,whichis3.8µVacross300ohmor
1.9µVacross 75ohm
Stereo- 37.3dBF,whichis40µVacross300ohmor
20µVacross 75ohm
FREQUENCYRESPONSE
Mono±1dB,20Hzto15kHz.
Stereo± 1 dB,20Hzto15kHz.
HARMONICDISTORTION
Mono0.08%at100Hz
0.08% at1 kHz
0.1% at10kHz
Stereo0.18%at100Hz
0.18% at1 kHz
0.25% at10kHz
SPURIOUSRESPONSE
100dB
IMAGERESPONSE
100dB
AMSUPPRESSION
60dB
STEREOSEPARATION
40dBat100Hz
50dBat1 kHz
35dBat10kHz
SIGNALTONOISERATIO
Mono80dB
Stereo75dB
TUNINGRANGE
88MHzto108MHz
TUNINGMETHODS
Manualtuning.
Pushbuttonstoselectanyoneofsixstations
storedintheelectronicmemory.
Scantuningupordown;scan-upcanbecontroll-
edremotely.
AUDIOOUTPUTLEVELS
1Vatfixedoutput
0to2.5Vatvariableoutputandheadphones.
POWERREQUIREMENTS
120V,50/60Hz,15W
SEMICONDUCTORCOMPLEMENT
33Transistors
15IntegratedCircuits
8Varactors
20LightEmittingDiodes(LED's)
34Diodes
MECHANICALINFORMATION
SIZE:
16incheswide(40.6cm)by3 5/8incheshigh(9.2
cm)by2 3/8incheshigh(6.0cm)by141/2inches
deep(36.8cm),includingconnectors.Knob
clearancerequiredis1 1/4inches(3.2cm)infront
ofmountingpanel.
FINISH:
Frontpanelisanodizedgoldandblackwith
specialgold/tealnomenclatureillumination.
Chassisisblack.
MOUNTING
ExclusiveMclntoshdevelopedprofessional
PANLOC
WEIGHT:
18pounds(8.2kg)net,30pounds(13.6kg)inship-
pingcarton.
INTERMODULATIONDISTORTION
Mono0.08%
Stereo0.18%
ALTERNATECHANNELSELECTIVITY
70dB
SCAREJECTION
60dB
GENERALINFORMATION
ANTENNAINPUTS
30012balancedand75ohmunbalanced
11
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PerformanceCharts
MR500FMSIGNALPERFORMANCE
98 MHz, 1 kHzMOD 100%
FREQUENCYINCYCLESPERSECOND
12
2010010001000020000
.14
.13
.12
.11
.10
.09
.08
.07
.06
.05
.04
.03
.02
MR500T.H.D.@ 100%MODULATION
98MHz
MICROVOLTS
100 1000 1k10k
dB
-10
-20
-30
-40
-50
-60
-70
-80
-90
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PerformanceCharts
MR500SELECTIVITY
DEVINkHz
-600-400-2000 +200+400+600
MR500FMFREQUENCYRESPONSE
ANDSEPARATION
+10
0
-10
-20
-30
-40
-50
-60
-70
-80
-90
-100
2010010001000020000
FREQUENCYINCYCLEPERSECOND
MR500SELECTIVITY
-600-400-2000 +200+400+600
0
-10
-20
-30
-40
-50
-60
-70
-80
-90
13
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14
Block
Diagram
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FMStationLog
15
STATION
DIAL
FREQ.
LOCATION
CITY,STATEANTENNA DIRECTION
REMARKS
TIME—DATE
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VARIOUSREGULATORYAGENCIES
REQUIRETHATWEBRINGTHE
FOLLOWINGINFORMATIONTO
YOURATTENTION.PLEASEREADIT
CAREFULLY.
WARNING:TOPREVENTFIREORSHOCK
HAZARD,DONOTEXPOSETHISUNITTO
RAINORMOISTURE.
TheMclntoshyouhavepurchasedisa ModelMR
500.Ithasa serialnumberlocatedontherearpanelof
thechassis.Recordthatserialnumberhere:
SerialNumber
Themodel,serialnumberandpurchasedateare
importanttoyouforanyfutureservice.Recordthe
purchasedatehere:
PurchaseDate
Uponapplication,MclntoshLaboratoryprovidesa
Three-YearServiceContract.YourMclntoshauthor-
izedServiceAgencycanexpediterepairswhenyou
providetheServiceContractwiththeinstrumentfor
repair.Toassist,recordyourServiceContractnumber
here:
ServiceContractNumber
16
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MclNTOSHLABORATORYINC.
2CHAMBERSST.,BINGHAMTON,N.Y.13903-9990
607-723-3512
Thecontinuousimprovementofitsproductsisthepolicyof
MclntoshLaboratoryIncorporatedwhoreservetherightto
improvedesignwithoutnotice.
PrintedinU.S.A.
BE022003
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