SBS FM30 User manual

Eddystone Broadcast Limited, Broadcast House, Lauriston Park, Pitchill, Evesham. WR11 8SN
Telephone[phone] Fax[phone]
Email [e-mail]
www.eddystone-broadcast.com
FM30
FMEXCITER/TRANSMITTER
&Transposer
Installation, Operatorand ServiceManual

FM30 SeriesTechnicalManualPage 2
CONTENTS
1Introduction
2Safety, Electricalhazard
3Safety, Toxichazard
4Unpacking
5Controlsand Connectors
6Installation
7Block diagram
8Specifications
9Contacting Eddystone Broadcast Limited
10 TechnicalSection Contents
11 Declaration of conformity
No part ofthismanualmaybe reproduced ortransmitted inanyformorbyanymeans, electronicor
mechanical, including photocopying, recording orinformation storage and retrievalsystems, forany purpose
otherthan the purchaser'spersonaluse, without the express written permission ofEddystone Broadcast Ltd.
Information inthisdocument issubject tochange without noticeand doesnot represent a commitment
on the part ofEddystone Broadcast Ltd. Eddystone Broadcast Ltd shall not be liableforanydirect, indirect,
consequential or incidentaldamagesasaresult ofthe useormisuseofthisequipment,
handbook or any related materials.

FM30 SeriesTechnicalManual Page 3
1Introduction
The FM30 isatop specification broadcast FMexciterthat isalsoideallysuited asa
lowpowerstand alone transmitter. Featuring wideband design techniques,
frequency adjustment iseasilyachieved byinternallyset direct reading dialswitches
-no furthertuning isrequired. Boththe international87.5-108MHzand Japanese
76-90MHzfrequency bandsarecatered for.
The FM30 usesthe renowned sbsultralinearmodulatortogivesuperbsound
reproduction withfreedomfromovershootsand artifacts. It will operateintoany
load without damage thanks toitsVSWRcut back circuit that protectsthe power
amplifierstage fromadverseoperating conditions.
The FM30 front panelmetering showsforwardand reflected powertogetherwith
internalvoltagesand the modulation level. Additionallyamonitorpoint forRF
output isprovided. Quick-viewstatusmonitoring using dualcolourLEDsindicate
that PLL lock, forwardpowerand reflected powerarewithinapreset tolerancewhen
green. The rearpanelincludesaremotecontrol/monitoring socket that allows
carriermuting and statussignalling toan externalsystem.
Veryconservativelyrated componentsand aswitchmode DC-DC converterare
used toensureextremelyhigh reliabilityand togivegood efficiency. The FM30 isin
servicewithbroadcastersworldwide and hasbeen giving manyyearsof trouble-free
service.
The FM30 isavailablewithan unbalanced multiplex/compositeinput (FM30), mono
balanced withlimiter(FM30/M)and balanced stereo withbuilt instereo
limiter/encoder(FM30/S). The FM30/RBRXincludesahigh qualitysinglechannel
receivermodulebased on the sbsRX400. The FM30/RBRXisafullyself contained
transposer, idealforrelaystations. Adigitalinput version (AES/EBU)withstereo
encoderisalsoavailable.
Additionallythe FM30 isavailablewithan input mixerformixing
balanced/unbalanced multiplex/compositewiththree SCAand abalanced mono
input with0, 50 and 75uSpre-emphasis.
All versionsof the FM30, apart fromthe multiplex/compositeinput type havea
switchablemultiplex/compositeloop forthe addition of RDSoranyotherSCA
system.
The FM30 can be used withthe sbsACU3, ACU4 or E2075 changeoverunit where
a fully backed up (redundant)systemisrequired.

FM30 SeriesTechnicalManualPage 4
2Safety, Electrical hazard
ImportantNotice
Thisunit containshigh voltageswhichcouldbe fatal. YOUMUSTALWAYS
ISOLATETHEUNITFROMTHEMAINSSUPPLYBY COMPLETELY
DISCONNECTING ITBEFOREATTEMPTING TO OPENTHECASE.
THISEQUIPMENTMUSTBE EARTHED.
Donot exposethisequipment torainoranyothersourceof water.
Incommon withall mainsoperated equipment, onlysuitablytrained competent
personnelshouldattempt toadjust, modifyorrepairthisequipment oroperateit with
the coverremoved. Incaseof anyquerypleasecontact yourlocalagent orsbs.
Anyunauthorised adjustment, modification orrepairof thisequipment may
invalidateanywarrantyand/orsafetyapprovalsthat apply.
Pleaseread all of thismanualand familiariseyourself withthe controlsbefore
attempting tousethisequipment.
Toensuresafety, it isthe responsibilityof the usertoinstall and operatethis
equipment inamannerthat iswithinthe manufacturersspecifications.

FM30 SeriesTechnicalManualPage 5
3Safety, Toxic hazard
Thisequipment includesdeviceswhichcontainBerylliumOxide whichisahighly
toxicsubstance. Inhalation oringestion of even tinyparticlescouldbe injuriousto
healthoreven FATAL!
Extremecaremust be exercised when replacing and discarding componentswhich
maycontainBerylliumOxide. If anysuchdeviceisphysicallydamaged you should
seekexpert advice, e.g. bycontacting the device'smanufacturers.
All suchdevicesmust be disposed of inaccordancewithlocalregulations. Inthe
UKyourlocalcouncil will haveatoxicwastedisposaldepartment who will be ableto
adviseyou. Elsewhereyou shouldcontact the responsibleauthorities.
NEVERDISPOSE OFADEVICECONTAINING BERYLLIUMOXIDEWITH
GENERALWASTE.

FM30 SeriesTechnicalManualPage 6
4Unpacking
Thispackage shouldcontain:-
1x FM30 Seriesbroadcast exciter/transmitter
1x IECPowerlead
1x FM30 seriesmanual
If anyitemsaremissing ordamaged pleaseinformyoursupplierimmediately.
InitialChecks
Ensurethat the FM30 hasbeen set tothe correct power/line voltage foryour
country.

FM30 SeriesTechnicalManualPage 7
5Controls and Connectors
FrontPanel:
PLL LOCK Modulatorfunctioning correctly(when green).
P.FWD Green when the RFoutput levelisabovea
predetermined level(see installation section).
P.REF Green whilethe reflected RFpowerisbelowapre-
determined level(see installation section). Red when the
VSWRcut-back systemisoperating.
LIMIT Showsgreen when internallimiteroption islimiting audio
input level.
SIGNAL(FM30/RBRX) Green whileasignalisreceived. Red when signalis
absent orbelowthe preset mutelevel.
O/PMonitor Monitorof RFoutput (approx. -40dBc). Thispoint should
not be used forharmonicorpowermeasurements
Meterand selector Selectsand indicatesimportant FM30 parameters.

FM30 SeriesTechnicalManualPage 8
RearPanel:
Audio/MPX input Unbalanced on BNC femaleconnectororbalanced on
femaleXLRconnectorwithoptionallimiter/encoderor
/SCAversion (pin1ground, pin2hot, pin3cold).
Multiplex/compositeloop WithswitchinONposition, the output of the
limiter/stereo encoder(if fitted)can be routed viaan
externalsystemsuchasan RDS/SCAencoder. Withthe
switchinthe OFF position, the multiplex/composite
output of the limiter/encoderispresent on the unbuffered
output connector, but the input connectoris
disconnected.
Monitor 25 wayfemaleD-type connector.
Pin1Forwardpoweralarm.
Pin2Reversepoweralarm.
Pin3PLL lock alarm.
Pin4MuteRFoutput (linktoground).
Pin5Receivesignalalarm(FM30/RBRX)
Pin25 Ground.
All outputsareopen collectorand lowintheirnormal
state. The output transistorsareBC184L's, whichcan
sinkup to100mAmaximumwithan absolutemaximum
switched voltage of 30V.
RFInput (FM30/RBRX) Ntype femaleconnector.
RFOut Ntype femaleconnector.
DC IN 4pinXLRmale, pin1and 2negative, 3and 4positive
for24Vto30VDC powersupply. Thissupplymaybe
connected at the sametimeasthe mainsinput. The
TX400 will then usethe DC supplyasabackup if the
mainssupplyfails.
ACMains Filtered IECmaleconnectorwithfuseinpull out drawer.
T3.15Afuse.

FM30 SeriesTechnicalManualPage 9
6Installation
RFleadsshouldbe made fromhigh qualitylowloss cableand connectorsof the
correct impedance, using the manufacturersrecommended termination techniques.
Sinceconnectorsareasourceof un-reliabilityinanysystem, the numberof
terminationsinanyRFlead shouldbe kept toaminimum.
All othercablesforaudioand controlsignalsshouldbe high qualityscreened types.
ForXLRconnectors, the screen shouldbe connected tothe connectorbody.
Beforenormaloperation of the FM30 can commencethe following parameterswill
requiresetting, assuming the equipment supplierhasnot done so:
6.1 Frequency
6.2 Output power
6.3 Forwardpoweralarm
6.4 Modulatorinput level
6.5 VSWRCut-back level
Pleaseread through ALL of the following stagesbeforeattempting anyadjustment.
When an automaticchange oversystemisinuse(suchasthe ACU3)thisshouldbe
disconnected/overridden suchthat the FM30 operatescontinuouslyduring the set-
up procedure.
6.1FREQUENCYSETTING
Setting the frequency isasimpleoperation. Direct reading dialsarelocated on the
PLL7 PCB. Forexample, toset afrequency of 107.30MHz, set the 10MHzdialto0,
the 1MHzdialto7, the 100kHzdialto3and the 12.5kHzdialto0. For98.35 set
10MHzdialto9, the 1MHzdialto8, the 100kHzdialto3and the 12.5kHzdialto4
(4x12.5kHz=50kHz).
Whilst the PhaseLocked Loop isLocking up the modulatoroutput ismuted
(indicated bythe front panelPLL LOCKLED). When the FM30 iseitherpowered up
orthe frequency changed, it will normallytakeabout 5secondsforthe PLL tolock
up. Howeverif the frequency ischanged fromahigh one toone at the bottomof the
band, withthe unit inoperation, it can takeup to10 secondsforthe PLL tolock up
properly.
6.2OUTPUTPOWER
Asmall trimmertoolorprecision screwdriverwill be required toadjust the output
power.
The output powershouldideallybe set using an accuratepowermeterconnected to
the RFoutput whichinturnshouldbe connected toan adequatelyrated dummy
load. If eitherof theseitemsarenot availablethen the front panelmetercouldbe
used and/orit couldbe operated intothe aerialorPA stage. Inthislattercasethe
Output Powercontrol(rearpanel)shouldbe set tominimum(counterclockwise)
beforepowering up the FM30.

FM30 SeriesTechnicalManualPage 10
Connect the FM30 tothe mainsorDC supplyand wait forthe PLL toLOCK(the
front panelLEDindicateslock when green). Using the rearpanelpoweradjust
control(PWR. ADJ.)set the powertothat required.
6.3FORWARD POWERALARM
Thissetting definesthe point at whichthe front panelP. FWD. light changestored
and alsothe point at whichaforwardpowerfault isindicated at the Control/Monitor
socket (fortelemetryand/oroperation of an automaticchange oversystem). Adjust
the output powertothe fault levelrequired. Thismust always be less than the
normaloutput powerlevelbyenough toprevent spurioustriggering, 1dBisan
appropriatemargin(80%of the correct full power). Adjust the PFWDOK(RV4)
controlon the FMTXDISboardsuchthat the front panelP. FWD. light just turnsred
fromgreen. Finallyset the output powerback tothe normaloutput level.
6.4MODULATORINPUTLEVEL
ForFM30/Mand FM30/Ssee the adjustment section of thismanualcovering LimX.
The FM30 isnormallysupplied withthe modulatorinput levelset sothat an input
levelof +8dBuoverthe range 5Hzto100kHz(without pre-emphasis)givesa
deviation of 75kHz. If adifferent levelisrequired then it will be necessarytoreset
the ‘MODLEVEL’control(VR2)on the PLL7 modulatorboard. Toset it properlya
deviation meterwill be required. Thisshouldbe connected tothe front panelO/P
monitorsocket. If adeviation meterisnot availablethen the front panelmeter
shouldbe used, though thiswill not be asaccurate. Applya400Hzsine waveat
the levelrequired formaximumdeviation (normally75kHz). Adjust VR2controlto
givethe required deviation. The front panelmeteriscalibrated at the factoryat the
centreof the operating frequency band. Therewill be averysmall calibration error
at eitherend of the band.
6.5VSWRCUT-BACK LEVEL
Thisisthe minimumRFoutput powerthat the FM30 will provide withabadly
matched load suchasadefectiveaerial. It shouldneverbe set above7.5Wto
protect the poweramplifierunit. Assupplied it will be set to4.5W. Toset adifferent
value turnthe FM30 output powerdowntominimum, connect apowermetertothe
output and disconnect the dummyload oraerial. RemovejumperLK1on the
FMTXDISPCB. Turnthe output powerup until the desired reflected powercut-back
levelisobtained. ReplaceLK1and adjust the CUTBACKcontrol(RV2)suchthat
the front panelP. REFLEDjust changesfromREDtoGREEN. Turnthe output
powerup tofull and if necessaryslightlyadjust the CUTBACKcontroltoreducethe
cut-back leveltothe value required. Finallyreset the forwardpowertothe required
level.

FM30 SeriesTechnicalManualPage 12
8Specifications
8.1Electrical specification
RFInterfaceports Output type N, monitorBNC. All 50
Poweroutput 0 -30Wtyp.
Poweroutput stability <±0.5dB1<±1.0dB2
Minimumreturnloss forfull poweroutput 8dB
Frequency range (Internationalversion) 87.5to108 MHzin12.5kHzsteps
Frequency range (Japaneseversion) 76 to90 MHzin12.5kHzsteps
Frequency error <±50Hz1<±100Hz2
Frequency drift (3monthinterval) <±50Hz
Frequency adjustment continuouslyvariableto<±10Hz
Muteattenuation (PLL out of lock) >90dB
Externalmutecontrolattenuation at full power >50dB
Deviation sensitivitystability3<±1%
Spuriousoutputs(76 to137Mhz@fc>±0.5MHz) <-100dBc
Harmonic&spuriousoutput (30MHzto1GHz) <-70dBc
SynchronousAM(500Hz@40kHzdev.) <-50dB
AMHum&Noise <-55dB
Input sensitivityfor75kHzdev(Factorysetting)+8dBuor3.5Vp/pUS/Canada (adj)
AFresponse(MPX Input) <±0.5dB(5Hz-100kHz)
MPX/CompositeTHD <0.05%at 75kHz
Powersupply 100/110/230VAC +10%/-20%
24 -30VDC
Powerconsumption <80VA
8.2Mechanical specification
Dimensions 3Ux260mm
Weight 6kg
Dimensionsexclude rearpanelconnectorsand front panelheatsink(40mm).
8.3Environmental specification
Ambient temperaturerange (normalconditions) 0to50 Celsius
Ambient temperaturerange (extremeconditions) -20 to60 Celsius
Humidity 90%non condensing
1Undernormaloperating conditions
2Underextremeoperating conditions
3Underall operating conditions

FM30 SeriesTechnicalManualPage 13
9Howto contact Eddystone Broadcast Limited
Forall enquiriespleasecontact yourlocalagent, orEddystone Broadcast Ltd directlyat:
Broadcast House
Lauriston Park
Pitchill
Evesham
WR11 8SN
UK
Ortelephone [phone]
Orfax+44(1386)871987
Oremail [e-mail]
Alternativelyvisit ourweb site: http://www.eddystone-broadcast.com/

FM30 SeriesTechnicalManualPage 14
10 Technical Section Contents
10.1 Introduction
10.2 PLL7 Modulator
10.3 FMTXPSUDC-DC Convertor
10.4 FM30 PA Amplifier
10.5 FMTX-DISPowerdistribution and metering/control
10.6 LimXCombined Limiter/stereo encoder
10.7 RBRX Module
10.8 SCA Input board
10.9 Adjustments
10.10 Power supply flow diagram
10.11 Wiring diagrams

FM30 SeriesTechnicalManualPage 15
10.1Introduction
The FM30 transmitter/exciterisbuilt around severaldistinct PCBmodules, broadly
asoutlined inthe block diagramof section 7. EachPCBperformsaseparate,
distinct function. Tofullyunderstand the operation of the FM30 it will be necessary
toknowhoweachboardisinterconnected withthe othersectionsof the unit.

FM30 SeriesTechnicalManualPage 16
10.2PLL7
The frequency determining element isformed bycoil L1 and varicap diodesVD1and
VD2,togetherwithcapacitorsC17-C20.Thesecomponentsareused aspartofa
cascode oscillatorwhoseoutputisthen buffered bytransistorT3.The RFoutputfrom
T3isimpedancematched tothe baseoftransistorT5byRFT1,a4to1matching
transformer.The high poweroutputfromT5isimpedancematched bycoilsL2 and L3
andassociatedcapacitorstothe50ohmoutputsocketCON2.Thesecomponentsalso
provide harmonicfiltering.
The PLL circuitisprimarilyIC2whichisaseriallyprogrammablePLL chip.The
microprocessorIC3readsthe dialswitchesat switchon and outputsaserialcode to
the PLL chipinaformatthatdeterminesthe outputfrequency thatthe PLL will tryand
lockthetransmitterto.ThePLLchipoutputscontrolpulsestotheloopfilterbuiltaround
opampIC4.TheloopfiltertakesthesharppulsesfromthePLLchipandconvertsthem
intoasmoothed signalreadytoapplytothe frequency determining components,
varicap diodesVD1and VD2.IC1isan analogue switchthatshortsouttwoofthe
resistorsinthe loop filterwhichenablesthe transmittertogeton frequency faster.
When the oscillatorison frequency the Analogue switchswitchesoutwhichgreatly
improvesthe audioresponseofthe transmitter.The microprocessorIC3determines
when toswitchthe analogue switchinand outbyreading the lock detectsignalsfrom
the PLL chip.The microprocessorcan alsousethisinformation toswitchoff transistor
T3withopen collectorconfigured T4whichmutesthe RFoutputwhen the transmitter
isout of lock. LED1providesvisualindication of the PLL locked condition.
The masterclock oscillator(OSC1)determinesthe accuracy of the output frequency.
Itisahighstabilitytemperaturecompensatedcrystaloscillator(TCXO).Thefrequency
can be trimmed ifrequired byadjusting the small trimmerlocated beneathaholeinthe
oscillatormodule.
Audioisfed intothe modulation inputconnectorCON2. Fromherethe signalpasses
tovariableresistorVR2wheremodulation levelscan be set, itisthen passed viaR29
tothe varicap diodes.

FM30 SeriesTechnicalManualPage 18
10.3FMTX-PSU
The powersupplytakesitsinputfromthe unregulated DC supply.It isused tosupply
the RFpoweramplifierwithitsDC supply.Thissupplymustvarybetween 5V and
15.5V dependent on the output powerrequired.
ThesupplyisdesignedaroundaSGS-Thomsonstep-downswitchingvoltageregulator,
type GS-R400V.Thissupplyprovidessoftstart, inhibit, overcurrentand overvoltage
protection.
The DC inputtothe boardisfused at10A (fastacting).Thisfuseshouldonlyfail ifthe
convertorsinternalover-voltagecrowbartripoperates.Thiswill normallyonlyhappen
iftherehasbeen an internalfailureinthe convertor.The fusemust onlybe replaced
withafast actingtype ofthe samevalue.
The DC supplyisdecoupled atthe convertorinputbyC1(LowESRtype). The same
type ofcapacitor, C2isused todecouplethe convertoroutput.
TheoutputvoltageissetbytheparallelcombinationofR4andtheexternal10k power
setcontrol.The parallelvalue ofthesetwocomponentsis6k for15.5V (maximum
power) and 0 for5.1V.The VSWRcut-back systemfeedsapositivecurrentintothe
VARinputwhenitoperates,toreducethe outputvoltage(and thereforeoutputpower).
T2,R8,R6,R7andzenerdiodeD2provideovervoltageprotectionintheeventthatthe
powersetcontrolshouldbecomeopen circuit, throughdisconnection orfailure.This
preventsdamagetotheRFpowerampunit. Thispartofthe circuitisdesigned onlyfor
protection.It shouldnotbe used tocontrolthe outputinnormalconditionssincethe
output stabilisation and noiseperformancewill be degraded.
The powersupplycan be shutdowntoprovide the mutingfacilityusingthe inhibit
inputs.Apositivevoltage>5Vcanbesuppliedtothe convertorviaD3and the potential
dividerR2/R3.AlternativelyR5can be linked toground,turningon T1.The former
inputisconnectedtothePLLOutofLockoutputfromthePLL7modulatorandthelatter
islinked tothe rearpanelcontrolconnectortoprovide the externalmutefacility.

FM30 SeriesTechnicalManualPage 20
10.4FM30 PA
The FM30 30Wamplifierisa2stagedesign,usingSemelabsMOSFETdevices.The
DC inputvoltagetothe amplifiercan varybetween 5-15.5V dependingon the required
output power.
ResistorsR9,R10,R11 forman inputattenuator.The inputmatchingcircuitforU1
comprisesL2,2:1transformerT2and R8.C6providesDC blocking.Biasisapplied
tothe gateofU1viaR2.
U1isasurface-mounted device.IfreplacementofU1isrequired,itisessentialtouse
thecorrecthot-airreworkequipment. UseofasolderingironmaydamagethePCBand
device.
U1's outputismatched tothe inputofthe mainoutputdeviceU2byC3,C4,C10,two
lengthsofstrip-line and R7.DC biasforU2isgenerated byD1whichrectifiesthe RF
inputatthe appropriatepointon the strip-line matchingsection.Thisarrangement
removesthebiasfromU2ifthe RFinputisremoved.OutputmatchingfromU2isdone
withalengthofstrip-line and C18, C7, C8, C19 and L3.
The firsttwosections,C11,L5,L6,C14,C15 and C20,ofthe outputfilteraretuned to
the 2nd and 3rd harmonics withthe finallowpass filterstagecomprisingL7 and C13.A
strip-linedirectionalcouplerisused tosensethe forwardand reflected powerlevels.
R12 nullsthe reflected powersensor.
Twoversionsofthe amplifierareproduced tocoverthe internationaland Japanese
frequencybands.The onlydifferencesbetween the twoarethe value ofsome
capacitorsand inductorsinthe matchingand filternetworks.