Kenwood TS-990S User manual

IN-DEPTH MANUAL
TS-990S In-depth Manual
November, 2013
CA-327W-E108
JVC KENWOOD Corporation
All Rights Reserved.

ii
COPYRIGHTS FOR THIS MANUAL
•JVCKENWOODCorporationshallownallcopyrightsand
intellectualpropertiesfortheproductandthemanuals,help
textsandrelevantdocumentsattachedtotheproductorthe
optionalsoftware.
•AuserisrequiredtoobtainapprovalfromJVCKENWOOD
corporation,inwriting,priortoredistributingthisdocumenton
apersonalwebpageorviapacketcommunication.
•Auserisprohibitedfromassigning,renting,leasingorreselling
thedocument.
•JVCKENWOODCorporationdoesnotwarrantthatquality
andfunctionsdescribedinthismanualcomplywitheach
user’spurposeofuseand,unlessspecicallydescribedinthis
manual,JVCKENWOODCorporationshallbefreefromany
responsibilityforanydefectsandindemnitiesforanydamages
orlosses.
SOFTWARE COPYRIGHTS
•Thetitletoandownershipofcopyrightsforsoftware,including
butnotlimitedtothermwareandoptionalsoftwarethatmay
bedistributedindividually,arereservedforJVCKENWOOD
Corporation.Thermwareshallmeanthesoftwarewhichcan
beembeddedinKENWOODproductmemoriesforproper
operation.
•Anymodifying,reverseengineering,copying,reproducing
ordisclosingonanInternetwebsiteofthesoftwareisstrictly
prohibited.
•AuserisrequiredtoobtainapprovalfromJVCKENWOOD
corporation,inwriting,priortoredistributingthismanualona
personalwebpageorviapacketcommunication.
•Furthermore,anyreselling,assigningortransferringofthe
softwareisalsostrictlyprohibitedwithoutembeddingthe
softwareinKENWOODproductmemories.
IMPORTANT NOTICES FOR SOFTWARE
Thesoftwareembeddedinthistransceiverconsistsofa
multiplenumberofandindividualsoftwarecomponents.Title
toandownershipofcopyrightsforeachsoftwarecomponentis
reservedforJVCKENWOODCorporationandtherespective
bonadeholder.
Thisproductemploysthesoftwarecomponentinaccordance
withtheEndUserLicenseAgreement(hereinafterreferredtoas
the“EULA”)stipulatedbyJVCKENWOODCorporationand/or
therespectivebonadeholder.
AccesstheURLbelowfordetailsofthesoftwarecomponent
stipulatedinthe“GPL/LPGL”.
http://www2.jvckenwood.com/gpl/index.html
TRADEMARKS
•KENWOODisaregisteredtrademarkofJVCKENWOOD
Corporation.
•Windows®XP,WindowsVista®,Windows®7,Windows®8and
theWindows®logoaretheregisteredtrademarksofMicrosoft
CorporationintheUnitedStatesandothercountries.
•.NETFrameworkisaregisteredtrademarkofMicrosoft
CorporationintheUnitedStatesandothercountries.
•IntelliMouseandIntelliPointareregisteredtrademarksof
MicrosoftCorporationintheUnitedStatesandothercountries.
•SHARCandtheSHARClogoareregisteredtrademarksof
AnalogDevices,Inc.
•Allotherproductnamesreferencedhereinaretrademarksor
registeredtrademarksoftheirrespectivemanufacturers.Marks
suchas™and®areomittedinthebodytext.
COPYRIGHTS FOR RECORDED AUDIO
Thebroadcastcontentrecordedinthistransceivermaynotbe
reused,exceptforpersonaluse,withoutpriorconsentofthe
rightsholderundercopyrightlaws.
INDEMNITY
•JVCKENWOODCorporationtakesallappropriatemeasures
toensurealldescriptionsinthismanualtobeaccurate;
however,thismanualmaystillcontaintyposandexpressions
thataremisleading.JVCKENWOODCorporationisentirely
freefromanyresponsibilitiesarisingfromanylossesor
damagescausedbysuchtyposorexpressions.
•JVCKENWOODCorporationhastherighttochangeor
improvetheproductspecications,etc.,describedinthis
manualwithoutpriornotice.JVCKENWOODCorporation
isentirelyfreefromanyresponsibilitiesforanylossesor
damagescausedbysuchchangesandimprovements.
•JVCKENWOODCorporationisentirelyfreefromany
responsibilitiesforanyfailures,damagesorlossesarising
from,orinconnectionwith,useofthetransceiverwithor
connectedtoanyexternalequipment.Failures,damages
orlossesshallincludethefailures,damagesorlossesthat
mayoccuratthePCconnectedtothetransceiverorin
storagedeviceshavingmemoryareasuchasaUSBash
drive.JVCKENWOODCorporationisentirelyfreefromany
responsibilitiesforanysecondaryfailures,damagesorlosses,
includingbutnotlimitedtothelossordamageofdataordata
lesstoredinthesememories.
•JVCKENWOODCorporationdoesnotwarrantthatquality
andfunctionsdescribedinthismanualcomplywithyour
purposeofuseand,unlessspecicallydescribedinthis
manual,JVCKENWOODCorporationshallbefreefrom
anyresponsibilitiesforanydefectsandindemnitiesforany
damagesorlosses.Selectionandinstallationofanyexternal
equipmentshallbedoneatyourownrisk.Youarefully
responsiblefortheuseandeectsofexternalequipment.
•JVCKENWOODCorporationshallbefreefromany
responsibilitiesforanyincidentallossesordamages,such
asmissingcommunicationsorcallopportunitiescausedbya
failureorperformanceerrorofthetransceiver.
•Wellawareinyourmind,wecannotanswertoanyandall
technicalinformationassociatedwithmethodofconnectionto,
congurationforandoperationofanexternaldeviceandPC
beyondourknowledge.
TREATMENT OF YOUR IMPORTANT DATA
Thereisalwaysariskoflosingyourimportantdatabya
transceiverfailure,occurrenceofanunforeseencontingency,
erroneousoperationorfaultybehaviorofthetransceiver.
Thedata,suchastheoperatinginformation,recordedaudio,
messages,congurationdata,andlogs,mustbebackedupas
necessarybyyourselfandstoredinanexternalstoragedevice
suchasaUSBashdrive.
URL AND CONTACTS OF JVC KENWOOD CORP.
ThelatestURLandcontactsofJVCKENWOODCorporation
atthetimewhenthismanualwaswrittenaredescribedin
thismanual.Duetochangesofsocialcircumstancesor
themanagementenvironment,theURLandcontactsof
JVCKENWOODCorporationmaychangefromtimetotime.

TABLE OF CONTENTS
iii
01 PROLOGUE
AbouttheReleaseoftheTS‑990S................................... 1
FeaturesoftheTS‑990S.................................................. 1
02 ANTENNASWITCHINGCIRCUIT
SignalingPaths................................................................ 2
UsingtheSameAntennaConnectorfortheMainBandand
theSubBand...........................................................................2
UsingDierentAntennaConnectorsfortheMainBandand
theSubBand...........................................................................3
RXAntennaFunction(RXINandRXOUTConnectors
On/O)....................................................................................3
ConnectinganExternalReceiver............................................3
03 RECEPTION
ReceiverConguration.................................................... 5
ConversionMethod.......................................................... 5
MainBandReceiver................................................................5
SubBandReceiver..................................................................6
Pre‑selector..................................................................... 8
NewMixer........................................................................ 9
RoongFilters................................................................ 10
WhatisaRoongFilter?.......................................................10
MainBandRoongFilters.....................................................10
AdditionalRoongFilter........................................................11
AdjacentInterferenceCharacteristics............................ 12
AGCCircuits.................................................................. 13
AnalogAGCCircuits..............................................................13
OptimizedGainDistribution...................................................13
DeectionoftheSMeterNeedle...........................................14
NoiseLevel............................................................................14
RFGainAdjustment..............................................................15
AGCO.................................................................................15
NoiseBlankers............................................................... 16
FeaturesoftheNB1andNB2...............................................16
AuxiliaryCircuits............................................................ 17
MediumWaveBandSensitivityRisers..................................17
04 TRANSMISSION
IFCircuitforCleanandStable200WOutputPower...... 18
FETFinalAmplierCircuit............................................. 18
High‑speedRelay‑controlledAntennaTuner.................. 19
LinearAmplierControl................................................. 19
REMOTEConnector.............................................................19
CongurationsintheAdvancedMenu...................................20
ALC.......................................................................................21
TransmitPowerLimiter..........................................................22
ALCOperationwhenanExternalDeviceisConnected.........22
DRVTerminal................................................................. 23
Protections..................................................................... 25
SWRProtection.....................................................................25
OvercurrentProtection..........................................................25
ThermalProtectionandFanControl......................................25
PowerSupply................................................................. 26
High‑EciencyLarge‑CapacityPowerSupply
Implemented.........................................................................26
PowerSaving.........................................................................26
Safety....................................................................................26
PowerFactorCorrection(PFC)toPreventHarmonicsin
theRectierCircuit................................................................27
ContinuousVariableRotationsandtheCoolingFan..............27
DC/DCConverter..................................................................27
05 LOCALOSCILLATOR
DDSandPLLSystem.................................................... 28
FirstLocalOscillatorfortheMainBandReceiver..................28
FirstLocalOscillatorfortheSubBandReceiver....................29
LocalOscillatorintheTransmitBlock....................................29
ReferenceFrequencyGeneratorCircuit......................... 30
06 DSP
FeaturesofTS‑990SDSPTechnologies........................ 32
DSPsandPeripheralHardware..................................... 32
SignalProcessingintheIFStage.................................. 34
IFAGCProcessing................................................................34
IFFilter..................................................................................35
InterferenceRejection...........................................................37
Reception...................................................................... 40
Demodulation........................................................................40
AFFilter.................................................................................41
AudioPeakFilter...................................................................42
NoiseReduction....................................................................42
BeatCancellers.....................................................................46
Transmission.................................................................. 47
Modulation............................................................................47
MicrophoneGainControl......................................................49
SpeechProcessors...............................................................49
Bandscope.................................................................... 51
FeaturesoftheFFTBandscope............................................51
ExamplesofSignalDisplays.................................................52
OtherFunctions............................................................. 54
TX/RXDSPEqualizers..........................................................54
VoiceGuidance.....................................................................54
OpticalDigitalI/O..................................................................55

TABLE OF CONTENTS
iv
07 SOFTWARE
ProcessorConnections.................................................. 56
DualTFTDisplay........................................................... 56
MainScreen..........................................................................56
Meter.....................................................................................57
FunctionCongurationScreensandBandscopeScreen......58
TouchScreen........................................................................58
SubScreen............................................................................58
SubScope.............................................................................59
MechanicalDialDisplay........................................................60
SwitchingSplitOperationwithanIntuitiveOperation..... 60
NewSplitFrequencySettingMethodforQuick
Operation....................................................................... 60
MultifariousMemoryChannels...................................... 61
StoringSta tesofSplitOperationandDualBandReception...61
MultifariousFunctionsSupportingtheOperator............. 61
FrequencyTracking...............................................................61
DATAModesCorrespondingtoaVarietyofOperations.........61
TransversedDialsinSWLMode............................................62
RTTYandPSKOperationwithoutusingaPC.......................63
BandscopewithaWaterfallDisplay.......................................64
AudioScopeforTX/RXAudioAnalysis.................................67
RecordingFunctionforMulti‑use...........................................68
ConguringtheClockusinganNTPServer..........................69
MenuandSubMenu.............................................................69
EasyFirmwareUpdating.......................................................69
PC‑Control............................................................................71
VariousSoftwareApplicationsforExtensive
Operations..................................................................... 74
SystemCongurations................................................... 75
RadioControlProgramARCP‑990................................ 77
BasicSpecicationsInheritedfromtheARCP‑590................77
UserInterface........................................................................77
LANConnectionwiththeTS‑990S........................................78
InternalVoIP(fortheKNSConnectionviaaLAN).................78
RadioHostProgramARHP‑990.................................... 79
BasicSpecicationsInheritedfromtheARHP‑590................79
UserInterface........................................................................80
DisablingtheAFGainControlfromtheARCP‑990...............80
LANConnectionwiththeTS‑990S........................................80
InternalVoIP(fortheKNSConnectionviaaLAN).................80
USBAudioControllerfortheARUA‑10.......................... 81
BasicFunctions.....................................................................81
Operation..............................................................................81
CongurationsforPracticalOperations.................................82
TX/RXAudioDelaysReduced...............................................82
VoIPProgramsARVP‑10H/ARVP‑10R.......................... 83
BasicFunctions.....................................................................83
VirtualCOMPortDriver................................................. 84
08 TERMINAL
PADDLEandKEYJacks................................................ 85
EXTSP1andEXTSP2Jacks........................................ 85
PHONESJack............................................................... 86
KEYPADJack................................................................ 86
METERJack.................................................................. 87
ACC2Connector........................................................... 88
OPTICALINandOPTICALOUTConnectors................ 89
DISPLAYConnector...................................................... 90
LANConnector.............................................................. 90
USBConnector(USB‑A)............................................... 91
USBConnector(USB‑B)............................................... 92
09 MECHANICALSTRUCTURE
InternalStructure........................................................... 93
Cooling.......................................................................... 94
TopPanelVibrationAnalysis.......................................... 96
Lift‑upMechanismoftheFrontBases............................ 96
PanelDesign.................................................................. 97
Operability..................................................................... 98
DualTFTDisplayandTouchPanel................................ 99
MainControlKnobMechanism.................................... 100
10 SP-990
AppearanceandFeatures........................................... 101
Speaker....................................................................... 101
Built‑inLow‑cut/High‑cutFilters................................... 102
SpeakerInputSelectSwitch........................................ 102

01 PROLOGUE
1
About the Release of the TS‑990S
SincetheTS‑900waslaunchedin1973,theNineHundredseriesofKENWOOD(TRIO)transceivershasbeenour
agshiphigh‑endHFtransceivers.FollowingtheTS‑900,theTS‑930,TS‑940,andTS‑950werelaunched.However,
morethan20yearshavenowpassedsincetheTS‑950SDXwaslaunched.
AttheendofFebruary2013,westartedshippingourlong‑awaitednewNineHundredserieslineup.
TheTS‑990Sispositionedasatop‑endtransceiverintheKENWOODHFtransceiverlineup,bothinnameandreality.
WeaccomplishedtheengineeringoftheTS‑990SenablingitnotonlytosucceedtheTS‑950butalsotobereputedasa
agshiptransceiverdespitetheTS‑990Sbeingthelast‑enteredagshiptransceiverinthemarketplace.
WhatweengineeredwiththemostcarefulattentiontopositiontheTS‑990Sasaagshiptransceiver,isthefundamental
transceiverperformance.Theperformanceincludesnotonlythetransmitandreceivecharacteristicsthatcanbe
measuredasmathematicalvaluesbutalsowhatyouwillhavebeensensedthatcanbecomprehensivelyreceived
throughactualtransceiveroperation.Thedetaileddesignaestheticextendsfromthecircuitsandcomponentsalltheway
tothetextureofthechassisandtheoperabilityofthepanel.
TheTS‑990ShasthefunctionalityrequiredforadvancedDXoperationaswellasaneye‑catchingdualTFTdisplayand
touchpanelthatlettheuserviewawiderangeofinformation.TherearesurprisinglymanybuttonsontheTS‑990S,
showninthephotographsincatalogs.However,webelieveyouwillunderstandourdesignconceptfortheTS‑990Sas
transceiverwhenyouseeandoperateit.
TheKENWOODHFtransceiversaimnotonlytoreceivesignalsfromandtransmitsignalstolocationsfurtheraway,
butalsototransmitandreceivesignalswithmorenaturalsound.Inotherwords,theTS‑990Shasbeendesignedasa
agshiptransceivernotonlyforDX’ersbutalsoforthoseoperatorswhoseekforbettersoundquality.
Thisin‑depthmanualiswrittenbytheTS‑990Sdesignerstodescribethetechnologiesandtechniquesusedto
implementtheconceptsmentionedabove.Wehopethismanualwillhelpyoutohaveadeeperunderstandingofthe
TS‑990S.
       November2013,KENWOODHFTransceiverDevelopmentTeam
Features of the TS‑990S
TheTS‑990SisaHF/50MHzall‑modetransceiverfeaturingareceptionperformancehighenoughtosatisfyDX’ers
allovertheworldandtheworld’srstdualTFTdisplay*1,enablinghigheroperabilityandinformationfeedbacktothe
operatorforbetterpracticaloperation.(*1AsofAugust2013,accordingtoourresearch)
ThereceivingcircuitsoftheTS‑990S,asuccessoroftheTS‑900,TS‑930,TS‑940,andTS‑950,realizedualband
receptionindierentbands.Forthemainband,narrowbandroongltersareimplementedusingafulldown‑conversion
methodtoraisetheadjacentinterferingsignaleliminationperformance,andanewtypeofmixerisusedtoimplement
a+40dBmlevelperformanceatthethirdinterceptpoint.Inaddition,theroongltersarecombinedwithanIFDSP
featuringsharplteringcharacteristicstoprovidesuperbinterferenceeliminationthatprovidesclearreceptionoftarget
signalsevenwhenthereissignalinterferenceduecontestingsignals.Forthesubband,weareusingthesamereceiving
circuitasoftheTS‑590S,whichwaslaunchedin2010andisreputedwithgoodperformance.
Forthedisplay,adualTFTdisplay(7″/3.5″)isemployedtoindicatedetailedoperatingstatuses.Themaindisplay
canshowthebandscopeandwaterfallscreensaswellasreadoutsofthemainband/subbandfrequencies,Smeter,
RIT/XIT,andmore.Asub‑displayisplaceddirectlyabovethemaintuningknob,andprovidesfunctionstodisplaythe
readoutsofthemainband/subbandfrequenciesandtheinformationaboutltering,audiospectrum,andmore,making
itextremelyusefulforDX’ers.
ThemaximumtransmissionpoweroftheTS‑990Sis200W.ToimplementQRP,itisequippedwithapowercontrol
functionthatcancontroldownto5W.Aswitchingpowersupplyisbuiltinthetransceivertosecurestabletransmissions.
TheTS‑990Sisequippedwithanautomaticantennatuner,andupto4antennascanbecentrallycontrolled.Memory
functionsareimplementedforeachbandtoallowquickbandswitchingandquickmanipulationsthroughsplitoperation.
TheSP‑990,adedicatedexternalspeaker,isavailableasanoption.ThespeakerisdesignedtomatchtheTS‑990S
design.ThesoundqualityisexcellentandtheSP‑990istuneddedicatedfortheTS‑990S.TheSP‑990has2inputlines.
Ifanothertransceiverisused,theSP‑990canbeusedasanexternalspeakerforthattransceiver.

02 ANTENNA SWITCHING CIRCUIT
2
Signaling Paths
TheTS‑990Shas4antennaconnectors,ANT1toANT4,andtheRX INandRX OUTconnectorsthatcanbeusedfora
reception‑dedicatedantennainputoranexternallterconnection.
Thereismorethanonepathfromtheantennastothereceivingcircuits,andthesepathscanbechangedaccordingto
theconguration.Thepathsfromtheantennastothereceivingcircuitscanbespeciedforeachreceptionbandinthe
mainbandandthesubband.TheantennaterminalsthatarenotspeciedareconnectedtoGND.
Using the Same Antenna Connector for the Main Band and the Sub Band
ANT 1 ANT 2 ANT 3 ANT 4 RX (OUT) RX (IN)
BPF, etc.
AT
FINAL
MAIN
SUB
Splitter
3 dB loss
Each Relay is in the
Off state (inactive).
Fig.1 SignalingPathswithANT1fortheMainBandandANT1fortheSubBand
Whentheantennaspeciedforthesubbandisthesameasthatconguredforthemainband,signalsareroutedas
illustratedinthegure“SignalingPathswithANT1fortheMainBandandANT1forSubBand".Thesignalsreceivedby
theantennaaresplitnearlyequaltothemainbandandthesubband,byasplitter.Inthiscase,thereadoutsoftheS
meterwiththegaincorrectedinthereceptionpathareprocessedtobethesamereadoutsthatareindicatedwhenno
receivesignalissplitbythesplitter.

3
ANTENNA SWITCHING CIRCUIT 02

ANT 1 ANT 2 ANT 3 ANT 4 RX (OUT) RX (IN)
BPF, etc.
AT
FINAL
MAIN
SUB
Splitter
3 dB loss
Each relay is in
the Off state (inactive).
Fig.2 SignalingPathswithANT1fortheMainBandandANT2fortheSubBand
Thegure“SignalingPathswithANT1fortheMainBandandANT2fortheSubBand”showsthecasewhendierent
antennasareselectedforthemainbandandthesubband.Thereceivedsignalsareenteredtothereceivingcircuits
fromtheantennas,notthroughthesplitter,andarenotsubjecttosensitivitydeteriorationbytheinsertionloss.

Whenareception‑dedicatedantennasuchasalow‑bandBeverageantennaorloopantennaisused,whenabandpass
lterisappendedexternally,orwhenaTransverterisconnected,theRXAntennafunctionenablestoreceivethesignals
viatheRX INconnectororsendthereceivedsignalsfromtheRX OUTconnector.
Pressingthe[RX ANT]keyandthenactivatingtheRXantennafunctionblocksthesignalsfromtheantennaconnectors
(ANT1toANT4)andallowsreceptionofsignalsdivertedtotheRX INconnectororenteredfromtheRX OUTconnector.
Toappendabandpasslter,itneedstobeconnectedbetweentheRX OUTandRX INconnectors.However,you
cannotreceivethesignalswithoutcorrectlyenteringthesignalsfromtheRX INconnector.
Connecting an External Receiver
ToreceivesignalsviaanotherreceiverbyusingtheRXantennafunction,connectasplitterbetweentheRX OUTand
RX INconnectorsasshowninthegure“ExampleofOperatingtheRXAntennaFunction(MainBand)”andmakethe
otherreceiverreceivethesignalssplitbythesplitter.
Thesplittertobeusedcansplittheenteredsignalswitha50Ωimpedanceequallythroughtwooutputterminals.
Connectoneoutputterminaltothe RX INconnectorwiththeTS‑990Sandtheothertotheotherreceiver.Youcan
connectacommerciallyavailablesplitterorauser‑manufacturedsplitterasdescribedbelow.

4
02 ANTENNA SWITCHING CIRCUIT
Simplyshort‑circuitingtheRX OUTconnector,RX INconnector,andanantennaconnectorwiththeotherreceiver
withoutusingasplittermaystartreception;however,itmaycauseimpedancematchingfailureoraproblemdueto
failureinisolationfromtheotherreceiver.
ANT 1 ANT 2 ANT 3 ANT 4 RX (OUT) RX (IN)
Splitter
Splitter
IN OUT 1
OUT 2
Other Receiver
AT
FINAL
MAIN
SUB
3 dB loss
Fig.3 ExampleofOperationusingtheRXAntennaFunction(MainBand)
Fig.4 ExampleofaSplitterCircuit
“ExampleofaSplitterCircuit”showsatheoreticaldiagramofasplittercircuit.Thiscircuitequallydistributessignals
enteredfromtheINterminalandsendsthemthroughtheOUT1andOUT2terminals,resultingina3dBinsertionloss.
Determinethenumberofturnsforthetransformertobeusedaccordingtofactorssuchasthemagneticpermeability
ofthecore.Alow‑capacitancecapacitormayneedtobeconnectedtotheinputoroutputinparalleltocorrectthe
frequencycharacteristics.IntheTS‑990S,asimilarcircuitisusedforsignaldistributiontothemainbandandthesub
band.
Note:
◆ Thiscircuitisatheoreticaldiagram.Wecanneitheranswerquestionsabouttheselectionofpartsorwiringofthesplitternor
guaranteeitsoperation.

03 RECEPTION
5

TheTS‑990Shastworeceivers;themainbandreceiverandthesubbandreceiver.Thiscongurationenablesdual
bandreceptionusingthemainbandandthesubbandeveniftwobandsareinthesamebandordierentbands.During
transmission,thereceptionstopsusingbothreceivers.Thebandscopecircuitcanselectsignalsfromeitherthemain
bandreceiverorthesubbandreceiver,regardlessoftheselectedband,andshowthestatusofIFsignalsselectedand
beingtransmitted(excludingFMmodulatedsignals).
Conversion Method
Main Band Receiver
Itisimportantforareceivertoeliminateinterferingsignalsthroughnarrowltersatanearlierstageandpassdesiredsignals
tothesubsequentcircuits.Usinglterswithbetterselectioncharacteristicsforearliereliminationofinterferingsignalsserves
topreventdistortioninthesubsequentcircuitsandimprovespracticalanti‑interferencecharacteristics.Therstmixer,through
whichanumberofinterferingsignalspass,needstohavehighinterceptpoint(referredtoasIPhereafter)characteristics.
IndevelopingtheTS‑990Smainbandreceiver,implementationofroonglterswithexcellentselectioncharacteristicsand
highIPcharacteristicswasthetop‑priority.Fortheroonglterimplementation,thefulldown‑conversionmethodoftherst
IFfrequencyof8.248MHzisadopted(the“down‑conversion”methodusedinthesystemisnotintendedforaconventional
congurationinwhichahighrstIFfrequency,e.g.,the73MHzbandisusedbutforacongurationinwhichalowrstIF
frequency,e.g.,8MHzbandor11MHzband,isused).TheuseofalowIFfrequencyallowslterswithsteepattenuation
characteristicstobeemployedandperformancesucientlytoleranttoadjacentinterferingsignalstobesecured.
Thenextissuewasthebandpassltersplacedinthefront‑endblockofthemainbandreceiver.TheuseofalowrstIFfrequency
allowsinterferenceonimagefrequenciesand/orspuriousreceptiontoeasilytakeplace,thusitisnecessarytoplaceanumberof
bandpasslterswithsteeperattenuationcharacteristics.Asshowninthetable“BandpassFilterDivisionintheMainBandFilter”,
bandpassltersfor15pathsareused,andforthemajoramateurbands(1.8MHz,3.5MHz,7MHz,14MHz,and21MHz),atoroidal
coilwithsteepattenuationcharacteristicsandhighIPcharacteristicsisused.Also,thebandpassltersforamateurbandsincluding
otherWARCbandsaredesignedforpositiveuseofpartswithhighQ(qualityfactor)anddistortionresistancecharacteristics.
Toeliminatedistortion‑causingelementsplacedonthesignalingpathsinthefront‑endblockofthemainbandreceiver,a
switchingmethodthroughrelaysisusedtoselectthebandpasslter,pre‑selector,pre‑amplier,post‑amplier,androonglter
forthemajoramateurbands.Thisalsohelpstoreduceinsertionlossandimprovetheisolationbetweenthesignalingpaths.
Table1 BandpassFilterDivisionintheMainBandReceiver
Band Filter Bandwidth
LF 30to522kHz
BC 522kHzto1.705MHz
1.8MHz 1.705to2.5MHz
3.5MHz 2.5to4.1MHz
5MHz 4.1to6.0MHz
7MHz 6.0to7.5MHz
10MHz 7.5to10.5MHz
14MHz 10.5to14.5MHz
18MHz 14.5to18.5MHz
21MHz 18.5to21.5MHz
24MHz 21.5to26.5MHz
28MHz 26.5to35MHz
35MHz 35to40MHz
40MHz 40to46.5MHz
50MHz 46.5to60MHz

6
03 RECEPTION
Thefollowingblockdiagramshowsthefront‑endblockorthemainbandreceiver.
ATT
270Hz
500Hz
2.7kHz
6kHz
15kHz
throughthroughthrough
Post AmpPre AmpPre Selector
0/6/12/18dB
1 st Mixer
Roofing
Filters
RF BPF
Fig.5 BlockDiagramoftheFront‑endBlockfortheMainBandReceiver
Thesignalreceivedbytheantennaentersthemainbandreceiverthroughtheantennaswitchingcircuit.Thebandpass
lterfortheselectedbandeliminatesinterferingsignalsoutsidetheband,thereceivedsignalisampliedbyapre‑
amplierandisthenconvertedtotherstIFsignal(8.248MHz)bytherstmixer.Therstmixerisdescribedlater.
Throughthepost‑amplierlinkedwiththebandscopebranchingcircuitandpre‑amplier,therstIFsignalentersa
roonglterthateliminatestheadjacentinterferingsignalsoutsidetheband.Theroongltersarealsodescribedlater.
The“BlockDiagramoftheIFStagefortheMainBandReceiver”shownbelowillustratesthediagramoftheblocks
subsequenttotheroonglters.TherstIFsignalroutesthroughtheAGCamplierandtherstIFampliertothe
secondmixer,whichconvertsittothesecondIFsignal(24kHz).ThesecondIFsignalenterstheDSPasthebaseband
signalthroughthesecondIFamplier,androutesthroughvarioussignalprocessingsuchasdemodulationafterIF
processingbytheAGC,lters,audiosignalprocessing,etc.InFMmode,therstIFsignal(8.248MHz)enterstheFM
systemIC,andthedetectedAFsignalenterstheDSPforaudiosignalprocessing.
CF1 455kHz BPF
BW: 9kHz (Narrow)
IC12
FM AF AMP FM
(AF)
CF2
SSB, CW, AM,
FSK, PSK
D32,D33
2rd mixer
FM IC9
FM IC
D31
D30
ATT
Q70
AGC AMP
Q49, Q52
IF AMP
Switching
MIFGC
IC10
IF AMP
SSB, CW, AM,
FSK, PSK
(24kHz)
MAGCV
455kHz BPF
BW: 12kHz (Wide)
MRIF
CN137
24kHz
IC11
Multiplexer
Fig.6 BlockDiagramoftheIFStagefortheMainBandReceiver
Sub Band Receiver
ThesubbandreceiverisrenedanddivertedfromthereceiveroftheTS‑590S.Forthemajoramateurbands(1.8MHz,
3.5MHz,7MHz,14MHz,and21MHz),itscircuitcongurationisfordown‑conversion.Inconditionsotherthanthose
describedinthe“ApplicableConditionsforDown‑Conversion”tablebelow,afrequencycongurationforup‑conversion
isappliedandcanbeusedforgeneralcoveragereception.

7
RECEPTION 03
Table2 ApplicableConditionsforDown‑Conversion
Band
1.8MHz(1.705to2.1MHz)
3.5MHz(3.4to4.1MHz)
7MHz(6.9to7.5MHz)
14MHz(13.9to14.5MHz)
21MHz(20.9to21.5MHz)
Pass
Bandwidth 2.7kHzorless
Mode SSB,CW,FSK,PSK
Theblockdiagrambelowshowsthefront‑endblockofthesubbandreceiver.Thesignalreceivedbytheantennacomesinto
thesubbandreceiverthroughtheantennaswitchingcircuit.Thebandpassltersdividedfor12pathseliminatetheinterfering
signalsoutsidetheband,andapre‑amplierampliesthesignalandsendsittotherstmixer.Therstmixerhasindependent
sectionsfordown‑conversionandup‑conversionrespectively,whichareswitchedbythesignalingpathconditions.
ATT
-6dB
LPF
522k~1.705MHz
1.705M~60M
x11
SRAT
(Sub RX RF in)
ATT
-12dB
S6DB S12DB
LPF
~60MHz
BC Trap
BPF
BPF
ATT
LPF
30k~522kHz
PRE OFF
Q219
Sub PRE AMP
To 1st Mixer
Fig.7 BlockDiagramoftheFront‑endBlockfortheSubBandReceiver
TheblockdiagrambelowshowstheIFcircuitofthesubbandreceiver.TherstIFsignal(11.374MHz)convertedby
thedown‑conversionmixerishandledasthesecondIFsignalafterpassingthroughthebandscopebranchingcircuit
andMCF.Ontheotherhand,therstIFsignal(73.095MHz)convertedbytheup‑conversionmixerpassesthroughthe
bandscopebranchingcircuit,MCFandrstIFamplier,andwillthenbeconvertedtothesecondIFsignal(10.695MHz)
bythesecondmixer.
From Sub PRE AMP
SRX-2
LPF
~60MHz
Q401~404
Sub RX 1st Mixer2
Q351~354
Sub RX 1st Mixer1
Q355, 356
SLO1 AMP1
MCF
Q405, 406
SLO1 AMP2
MCF
TX
XF351
11.374MHz
XF401
73.095MHz
Scope unit
11.374MHz 73.095MHz
LPF+
11.374M NOTCH
13.174~32.195MHz 73.125~133.095MHz
SLO1
TX
Q408
Sub 1st IF AMP
D405,406
Sub 2nd Mixer
Q410
SLO2 AMP
SLO2
62.4MHz
TX
11.374MHz
10.695MHz To Sub 2nd IF AMP1
(Q481)
SRX-1
DIV.
DIV.
Fig.8 BlockDiagramoftheIFCircuitfortheSubBandReceiver
Afterthat,thesecondIFsignalonadierentpathpassesthroughthesecondIFamplierandNBgateandentersa
roonglter,whicheliminatesadjacentinterferingsignalsoutsidetheband.The“PhotographoftheRoongFilterinthe
SubBandReceiver”belowshowstheroonglters.ThesecondIFsignal,whichpassesthroughtheAGCamplierand
secondIFamplier,isconvertedbythethirdmixertothethirdIFsignal(24kHz).ThethirdIFsignalenterstheDSPas
thebasebandsignalthroughthethirdIFamplier,andpassesthroughvarioussignalprocessingsuchasIFprocessing,
demodulation,andaudiosignalprocessing.InFMmode,thesecondIFsignal(10.695MHz)enterstheFMsystemIC,
andthedetectedAFsignalfeedstotheDSPfortheaudiosignalprocessing.

8
03 reception
Fig. 9 Photograph of the Roong Filter in the Sub Band Receiver
Pre-selector
The pre-selector is implemented to attenuate, by using a narrowband lter, the in-band interfering signals that cannot be eliminated
by the bandpass lters in the front-end block of the main band receiver and to elicit the desired signals. The “Pre-Selector Unitary
Resonance Circuit” shows its internal resonance circuit. A method of relay-switching of highly accurate capacitors, toroidal coils,
etc. enables it to change the precisely tuned frequency in accordance with the received frequency in the HF amateur bands. The
“Available Band and Step Frequency Specications” table shows the available bands and step frequencies.
Fig. 10 Pre-Selector Unitary Resonance Circuit
Table 3 Available Band and Step Frequency Specications
Band Range Step Frequency 3 dB Passband
Width
1.8 MHz 1.79750 to 2.00499 MHz 2.5 kHz 20 kHz
3.5 MHz 3.49250 to 4.01749 MHz 7.5 kHz 50 kHz
5 MHz 5.24000 to 5.46999 MHz 10.0 kHz 100 kHz
7 MHz 6.98000 to 7.33999 MHz 20.0 kHz 120 kHz
10 MHz 9.98000 to 10.17999 MHz 20.0 kHz 220 kHz
14 MHz 13.95000 to 14.44999 MHz 50.0 kHz 620 kHz
18 MHz 18.01800 to 18.26799 MHz 50.0 kHz 880 kHz
21 MHz 20.90000 to 21.69999 MHz 100.0 kHz 880 kHz
24 MHz 24.79000 to 25.18999 MHz 100.0 kHz 1120 kHz
28 MHz 27.90000 to 29.89999 MHz 100.0 kHz 1170 kHz
The frequency response shape a steep single-peaked pattern. A large-sized coil with less loss is used; however, a large
insertion loss may be inevitable; therefore, an amplier is placed after the pre-selector to compensate the loss. Signal
level correction in connection with the amplier is also applied to suppress deection of the S meter needle. To prevent
the reception noise level from rising, it is designed so that the pre-ampliers do not work in conjunction with it. Thus,
enabling the pre-selector disables the pre-ampliers.

9
RECEPTION 03
The“FrequencyResponse”gureshowsanexampleoftypicalPre‑selectorFrequencyAmplitudecharacteristics.
Fig.11 FrequencyResponse
Pressingthe[P.SEL] keytoturnthepre‑selectoronmakesthetuninglterwaveform‑shapedbytherelayoperation
logicconguredasthefactorydefault,followingthefrequencydisplayedatthemainbandreception.Pressingand
holdingthe[P.SEL] keyshiftsthecenterfrequencyofthetuninglterupto±20steps.Forinstance,whenastrong
adjacentinterferingsignalsuppressesthedesiredsignal,shiftingthecenterfrequencyintheoppositedirectionof
theinterferingsignalsattenuatestheleveloftheinterferingsignalsinsteadofattenuatingthedesiredsignal,thusit
eectivelyreducesinterferenceasmuchaspossible.
New Mixer
Therstmixerwasapartoftheblockonthemainbandreceiverandwasexaminedthelongest.Doublebalanced
mixerswithconventionalJ‑FETimplementationhavebeenunabletofullysatisfytherequiredIP3characteristics.
Tosatisfytherequirement,amixercalledthe“H‑modemixer”,whichemploysthedoublebalancedgroundedswitch
typethatisdierentfromconventionaltypes,isemployedfortherstmixer.ThecircuitofthemixercanturntheGND
terminatingendsonthesignalingpathsOnorO,tominimizethemixerdistortion.
Fortheswitchelements,busswitchesareusedandturnedon/oonlybylow‑powerlocaloscillatorsignals.FortheRF
inputandIFoutputofthemixer,largebaluntransformerswithdistortionresistancecharacteristicsareused,andthe
windingmethodsandmaterialsofthecoreswithdierentmagneticpermeabilityarecarefullychosenandexamined.
Furthermore,afterthemixer,aduplexercircuitisplacedtostabilizetheimpedanceoftheroongltersinawiderband.
L55
RF
+2.5V
IC7
x4
+2.5V
MLO1
8.278~51.752MHz
IC8
L59
L60
1st IF
8.248MHz
Fig.12 DoubleBalancedGroundedSwitchTypeMixer

10
03 RECEPTION


Thissectiondescribestheroonglter,whichisthemostimportantinthemainbandreceiver.Theroonglterisalter
placedattheceiling,orthe“roof”oftheintermediatefrequency(IF)circuitofthereceiver.Inotherwords,thisrepresents
anarrowbandlterwherethesignalconvertedtotheintermediatefrequencyrstpassesthrough.Areceivedsignal
includesanumberofstrongadjacentsignalsotherthanthedesiredsignal,thusattenuatingtheundesiredsignalsin
anearlystageinaprecedingcircuitenablesthesignaltonotbedistortedinthesubsequentamplifyingcircuit.The
highinterceptpointobtainedbythehigh‑performancerstmixergivesfullplaytoitsabilityinafrequencydomain
slightlydistantfromthedesiredsignalattenuatedbytheroonglter.Ifthelevelofadjacentsignalsinevitablypassing
throughtheroonglterishigh,itcausesdistortiontooccurinthesubsequentIFamplier,mixer,andothercircuits,
andthedynamicrangedeterioratesontheadjacentfrequencies.Thisiswhytheroongltersmustbenarrowedtotheir
minimumandattenuatedtothesteepestdirection.
Forthemainband,8.248MHzisselectedforrstIFfrequency,andforthesubbandwiththedown‑conversionsetting,
11.374MHzisselectedfortherstIFfrequency;theserstIFfrequencysettingsenablelterswithgoodattenuation
characteristicsinanarrowbandandfewercharacteristicchangesbytemperature.
Note:
◆ Forexample,narrowbandlterswithahighfrequency,e.g.,73MHz,maybeimplemented,butsuchltershavelarge
characteristicchangesbytemperatureandcauseproblemssuchasincreasedattenuation,thusdonotserveforpractical
operation.

FiveroongltersareusedasnarrowbandltersofhighIPcharacteristicsimplementedbythefulldown‑conversion
method.The“PhotographofRoongFilterintheMainBandReceiver”showstheroonglters.Inthephotograph,the
15kHz,6kHz,2.7kHz,500Hz,and270Hzbandwidthltersaremountedfromthelowerrightside.Inthatorder.The
15kHzand6kHzbandwidthltersare4‑polemonolithiccrystallters(MCF).The2.7kHzbandwidthlterisa6‑pole
monolithiccrystallter.The500Hzand270Hzbandwidthltersarestructuredastheladdertypetosuppressin‑band
insertionlossesandsteeplyshapetheadjacentout‑of‑bandattenuationcharacteristics.The“Frequencyresponseof
the500HzBandwidth”and”Frequencyresponseofthe270HzBandwidth”guresshowtheladderlterfrequency
response.
Theroongltersforthemainbandreceivercanbeselectedregardlessofoperationmode(excludingFMmode).
Pressingandholdingthe[FIL/SEL](M)keyopenstheRX Filterscreenonthemaindisplay.Thescreenallowsyouto
selecttheroongltertobeused.
Fig.13 PhotographofRoongFilterintheMainBandReceiver

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RECEPTION 03
Fig.14 Frequencyresponseof
the500HzBandwidth
Fig.15 Frequencyresponseof
the270HzBandwidth

TheTS‑990Smainbandreceiverhasaslottomountaroonglterinadditiontothevebuilt‑inroonglters.(Wehave
noplantocommercializeadditionalroongltersonourown.)
Fig.16 AdditionalRoongFilterMountingSlot
Ifanadditionalroonglterismounted,changethedefaultvalueof“O”inAdvancedMenu6“Bandwidth(Additional
RoongFilter)”toyourdesiredlterbandwidth,andthenpressandholdthe[FIL/SEL] (M)keytoopentheRX Filter
screen.Inthescreen,changethecongurationfor“Roof”to“Add.”toenabletheadditionalroonglter.If“Auto”issetto
“Roof”,theadditionalroonglterispreferentiallyselecteddependingontheIFlterbandwidth.
Concerningthebuilt‑inroonglters,thePINdiode‑typeattenuatorattheIFstagecorrectsthegain,causingno
dierenceinSmeterneedledeection,whetheralterisappliedornot.But,ifanadditionalroonglterisused,itis
necessarytocorrecttheSmeterneedledeectionbyadierenceoftheinsertionloss.Toreceiveasignalwithastable
signalstrength,changetheattenuationoftheadditionalroonglterinAdvancedMenu7“Attenuation(Additional
RoongFilter)”.The“ElectricalSpecications”tableshowstheadditionalroonglterelectricalspecications.The
“Dimensions(Reference)”diagramshowstheadditionalroonglterdimensionaldiagram(reference).
Table4 ElectricalSpecications
CenterFrequency 8.248MHz
Bandwidth(‑6dB) 300to3500Hz
TerminatingImpedance 50Ω
Insertionloss 8dBorless

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03 RECEPTION
47.5
2.5
2.52.5
62.0
23.755.15
23.35
14.45 6.2
ϕ1.0 ~ 1.2
16.1
R0.7
11.4
1.2
17.5
GND
GND
GNDGND
OUT
IN
No part can be mounted on the reverse.
3.7 x 5.3
Fig.17 Dimensions(Reference,Unit:mm,topview)
Adjacent Interference Characteristics
The“IP3CharacteristicsComparison”graphshowsacomparisonbetweentheTS‑990Smainbandreceiver(orange)
andthereceiverofaconventionaltransceiver(gray).ItindicatesthattheIP3characteristicsareimprovedtothe+40
dBmlevelanduniformlysettledtoadjacentinterferencesignalsintherangeof2to10kHzfromthereceptionfrequency.
Inaddition,the110dBclassdynamicrange,whichexceedsthe105dBclassoftheTS‑590S,hasbeenachieved.
Fig.18 IP3CharacteristicsComparison
Note:
◆ Thehorizontalaxisistheseparationtothedesiredsignaloftheinterferencesignalfrequency(2waves).At10kHz,
interferingsignal1isthe+10kHzreceptionfrequency,andinterferencesignal2isthe+20kHzreceptionfrequency.
◆ Theresultofmeasurementsisanexamplethatdoesnotguaranteetheperformanceoftherespectiveproducts.
◆ ThemeasurementsconformtoameasurementmethodspeciedbytheARRL.

13
RECEPTION 03
AGC Circuits
Analog AGC Circuits
Toachievehighadjacentdynamicrangecharacteristics,ananalogAGCcircuitisusedtogethertomaketheA/DConverter
worktoitsperformancelimit.TheAGCcircuitisrequiredtohavelownoiseandawidedynamicrange,widecontrolrange,and
linearitytothecontrol.TheTS‑990Simplementshigh‑precisionAGCresponsecharacteristicswithanAGCcircuitinwhicha
dual‑gateMOSFETisused(showninthediagram“AGCCircuitwithaDual‑GateMOSFET”)andcorrectionismadebyDSP.
Fig.19 AGCCircuitwithaDual‑GateMOSFET
ThegraphbelowshowstheAGCresponsecharacteristicstoacontrolvoltageinthecircuitcongurationwithadual‑
gateMOSFET.Sucientcontrolrange,dynamicrange,andlinearityaresecured.
Dual Gate MOSFET
Fig.20 AGCResponseCharacteristicstoaControlVoltage
Optimized Gain Distribution
Themixer,whichisthekeyblockinthemainbandreceiverandisnewlydeveloped,hasrelativelylargerconversionloss
thanthatofconventionalmixers.Therefore,thecircuitisstructuredtoworkinconjunctionwithapost‑amplier,which
isplacedinthemixeroutput,duringoperationofthepre‑amplier.Pressingthe[P.AMP]keyimprovesthereception
sensitivitybyapproximately14dBbypre‑amplier1andthepost‑amplierinareceptionbandbelow21.5MHzand
approximately18dBbypre‑amplier2andthepost‑amplierinareceptionbandabove21.5MHz.
Theattenuationoutsidethebandisfullyobtainedbytheroonglterswithgoodselectivity.Therefore,theanalogAGCcircuit
andhigh‑gainIFamplierareplacedinalaterstagesothatundistortedIFsignalsaresuppliedasbasebandsignalstotheDSP.

14
03 RECEPTION

TheIARU(InternationalAmateurRadioUnion)standardscalerequires‑73dBmastheSmeterleveltopointS9.However,
concerningtheSmeterneedledeection,onallourproducts,theSmeterlevelis‑81dBmtopointS9inthe14MHzbandwhile
apre‑amplierison.TheTS‑990SalsoprovidesSmeterneedledeectionfamiliartooperatorsusingaconventionalmodel.
Turningothepre‑amplierslowersthegainandtheSmeterneedledeection.Thegainchangesbyapre‑amplierby
approximately12dBintheamateurbandsuptothe21MHzbandandbyapproximately20dBinhigherbands.
The“SMeterLevels(Reference)”tableshowstheindicatedlevelsoftheSmeter.(TheSmeterlevelisadjustedtopoint
S1,S9,orS9+60inthe14/50MHzbands.)
InFMmode,youcanselectthesameconguration(High)asthathasbeenconguredforconventionalmodels,ora
lowervalueenablingtolowertheSmetersensitivity,throughMenu0‑08“FMModeS‑meterSensitivity”.
Table5 SMeterLevels(Reference)
S Meter 0.03 to 21.5
MHz 21.5 to 60 MHz  
S1(3dots) ‑107.0dBm ‑114.0dBm ‑117.0dBm ‑117.0dBm
S3(11dots) ‑100.5dBm ‑107.5dBm ‑114.4dBm ‑112.8dBm
S5(19dots) ‑94.0dBm ‑101.0dBm ‑111.8dBm ‑108.5dBm
S7(27dots) ‑87.5dBm ‑94.5dBm ‑109.2dBm ‑104.3dBm
S9(35dots) ‑81.0dBm ‑88.0dBm ‑106.6dBm ‑100.0dBm
S9+20(48dots) ‑61.0dBm ‑68.0dBm ‑102.4dBm ‑93.2dBm
S9+40(59dots) ‑41.0dBm ‑48.0dBm ‑98.9dBm ‑87.4dBm
S9+60(70dots) ‑21.0dBm ‑28.0dBm ‑95.0dBm ‑81.0dBm
Fig.21 SMeterReadout(Analog) Fig.22 SMeterReadout(Digital)
Noise Level
Withapre‑amplieractive,thesensitivityincreasesbythegainandinternalnoise,andtheSmeterneedleis
easilydeectedandthenoiselevelrises.Thesensitivitydecreaseswiththepre‑amplierinactive;however,theIP
characteristicsimprove,noiselevellowers,andtheSmeterneedlecannotbedeected.Inaddition,theIFgainis
correctedsothatthegain,sensitivity,deectionoftheSmeterneedle,noiselevel,andotherfactorsappropriately
change.
Withapre‑amplieractiveinabandbelow21.5MHz,thenoiselevelwillnotincrease.However,withapre‑amplier
activeinabandabove21.5MHz,thenoiselevelincreaserelatively.

15
RECEPTION 03
RF Gain Adjustment
KENWOODHF‑bandtransceiversaredesignedwithourconsistentphilosophytobalancethelevels,suchasthe
sensitivity,Smeterneedledeection,pre‑ampliergain,gaincorrection,andotherfactors.Iftheinputlevelfroman
antennaislow,(internal)noisemaybeconspicuous.Ifnoiseisconspicuous,reducingtheIFgaincanlowerthenoise
level.Forthatpurpose,the[RF]knobisprovided.Rotatingthe[RF]knobcounterclockwisereducestheIFgainand
consequentlylowersthenoiselevel.Slightlyloweringthegaindoesnotchangethereceptionsensitivity.TheSmeter
showsthegainreductionbytheAGCandthe[RF]knob,thustheSmeterneedledeectsbythegainreduction.Inthe
rangetheAGCisapplicable,theSmetersensitivitydoesnotchange.
Placingthe[RF]knobtothe3o`clockpositionreducestheIFgainbyapproximately6dBfromthemaximumand
reducesthenoiselevelatnosignalbyapproximately6dB.ThegainreductioncausestheSmeterneedletodeect
closertoS3.A6dBgainreductioncausesthesensitivitytochangelittle,andthereceptionsoundvolumedoesnot
changewithreceptionofausualsignalthatmakestheSmeterneedledeect.Ifthenoiselevelisnoticeable,adjustthe
RFgain.

TheAGCtimeconstantsforsuchastheattacktime,releasetime,andholdtimeareoptimizedforapracticalradio
wavesstate.However,forreceptionofasignaleasilyburiedinnoise,turningtheAGComayoccasionallyincreaseits
performance.Insuchacase,theAGCcanbedisabledwithapressofthe[AGC OFF]key.
WiththeAGCinactive,thesignallevelwillnotbecontrolledtobethecertainvolumelevel,andthespeakermayemit
veryloudsounds.ThisiswhyaconrmationmessageappearsbeforetheAGCisturnedotopromptattentiontoloud
sounds.
BeforeturningtheAGCo,youmustadjusttheRFgaintoasignallevelthatmakestheSmeterneedledeect.Rotate
the[RF]knobcounterclockwisetolowertheRFgain,lettingtheSmeterneedledeectslightlywider.Thispreventsloud
soundsfrombeingemittedwhiletheAGCisinactive.
IfalargesignalisenteredwhiletheAGCisinactive,theSmeterneedledeectsuptothelevelspeciedfortheRFgain
andthereceptionsoundvolumeincreasesuptoacertainlevel.However,ifthislevelisexceeded,thereceptionaudio
volumereachesitslimitandsuddendistortiontakesplace.Thisisintendedtosetlimitssothattheallowablelevelsare
notexceededintheD/Aconverterandthroughsignalprocessing.

16
03 RECEPTION
Noise Blankers
Features of the NB1 and NB2
TheTS‑990Shastwonoiseblankers;NB1foranalogprocessingandNB2fordigitalprocessingbyDSP.
NB1iseectiveforshort‑cyclepulses,suchasignitionnoise.NB2iseectivefornoisethattheanalognoiseblanker
(NB1)cannotfollow.Thefollowingblockdiagramshowstheanalognoiseblanker(NB1).
Buffer NB AMP2 NB AMP3 NB AMP4 Buffer
Noise
Detection
NB AGC
AMP
AGC
Noise Blanker
Threshold Level
Switching
Mute Signal


Fig.23 NoiseBlankerCircuit(NB1)BlockDiagram
NB1hasthecircuitcongurationinheritedfromthatofconventionalmodels,whichiseectiveforweaknoise.Apulse
signalafterpassingthroughanarrowbandlterchangesitsnoisewaveform,increasingthepulsewidth.Thus,atthe
roonglterinputstage,whichisnotsubjecttoinuenceofpulsenoise,signalsarepickedupandswitchcircuits
operate.
Forexample,ifapulsewithashortcycleisenteredasshownindiagram1,theAGCinthenoiseblankercircuitdoesnot
reacttoit,thustheswitchfunctionsandamutedsignalwillbepresent.
Tothecontrary,ifapulsewithalongcycleisenteredasshownindiagram2,theAGCreactstoitandcorrectsthegain,
thustheswitchdoesnotfunctionandthesignalwillnotbemuted.
ToadjusttheeectofNB1,rotatethe[NB1]knobforthemainband,orpressthe[NB1/SEL]keyforthesubband.The
largerthevaluedisplayed,themoretheeecttonoise.
TheDSPdigitalnoiseblanker(NB2)mayinsucientlytakeeectifthedesiredsignalisstrongortheroonglter
bandwidthisnarrow.However,inCWmode,andinthecaseofabandwidthof500Hzorlower,itmaybeunexpectedly
eective.ThisisbecauseNB2operatesexibly,conformingtheblankingtimetothepulselength.
NB2producesaneectonacquisitionofaweakdesiredsignalthatisburiedinnoiseandwithalongpulsewidththat
NB1cannoteliminate.Chapter6,DSP,describesthedetailsofNB2.
How to Use the NBs and NRs
Thereisaterm:“NBcross‑modulation”.Thismeansthesituationofmodulationinwhichanoiseblankerisrunning
falselyrecognizesthedesiredsignaloradjacentsignalasanoisepulse.Itdoesnotrelatetothefront‑endperformance.
Onceafalserecognitiontakesplace,thenoisetobeeliminatedasofnon‑desiredsignalsclearlyappears(ornoise
clearlyappearstothekeyinginCW)orthedesiredsignalisheardwithdistortion.
Theformercaseiscausedbythenoiseblankerbeingunabletoproduceaneectwhenthedesiredsignalisrelatively
strong,orwhenastrongsignalappearsinanadjacentfrequency.ThisisbecauseastrongsignalactivatestheAGCof
thenoiseblankersothatthenoiseampliergaindecreases.Ifthelevelofthesignalandthelevelofthepulsenoiseare
equivalent,placinganattenuatorordisablingthepre‑amplierdecreasesthefront‑endgainandmayrestoretheeect
ofthenoiseblanker.
Thelattercasemayeasilytakeplacebyincreasingthenoiseblankerlevel.Thisisatrade‑oandisinevitable.Ifthe
receivedsignalappearstobedistorted,turnothenoiseblankerandcheckthereceivedsound.Turnonandadjustthe
noiseblankerleveltorectifythedistortionifdoingsotakeseect.