Crown FM500 User manual

ii
Revision Control
Revision PrintDate
InitialRelease(K80713–9) June1996
Revision1(101033–1) November1996
Revision2(101033–2) August1997
Revision3(900239–1) February1998
Revision4(900239–1) October1998
Revision5(901047-1) October1999
Revision6(901047-2) May 2000
Revision7 March2002
Revision8 February2006
Important Notices
©2006, Crown Broadcast, a division of International Radio and Electronics, Inc.
Portions of this document were originally copyrighted by Michael P. Axman in 1991.
All rights reserved. No part of this publication may be reproduced, transmitted,
transcribed, stored in a retrieval system, or translated into any language in any
form by any means without the written permission of Crown International, Inc.
Printed in U.S.A.
Sony and RCA are trademarks of their respective companies.
Crown attempts to provide information that is accurate, complete, and useful.
Should you find inadequacies in the text, please send your comments to the follow-
ingaddress:
InternationalRadioandElectronics
25166 Leer Drive,P.O.Box 2000
Elkhart,Indiana,46515-2000U.S.A.

iii
ContentsContents
ContentsContents
Contents
Section 1—Getting Acquainted ..................................... 1–1
1.1 YourTransmitter ...............................................................................................1–2
1.2 ApplicationsandOptions...................................................................................1–3
1.2.1 Stand-Alone ..................................................................................................1–4
1.2.2 Backup..........................................................................................................1–4
1.2.3 Booster .........................................................................................................1–4
1.2.4 Exciter...........................................................................................................1–4
1.2.5 Translator......................................................................................................1–5
1.2.6 Satellator ......................................................................................................1–6
1.3 Transmitter/ExciterSpecifications .....................................................................1–7
1.4 ReceiverSpecifications .....................................................................................1–9
1.5 SafetyConsiderations......................................................................................1–10
1.5.1 Dangers ......................................................................................................1–10
1.5.2 Warnings ....................................................................................................1–10
1.5.3 Cautions......................................................................................................1–10
Section2—Installation ............................................... 2–1
2.1 OperatingEnvironment......................................................................................2–2
2.2 Remove PA Tray Spacers ..................................................................................2–2
2.3 PowerConnections ...........................................................................................2–3
2.4 Frequency(Channel)Selection ..........................................................................2–5
2.4.1 ModulationCompensator..............................................................................2–6
2.4.2 RFTuning Adjustments.................................................................................2–7
2.5 ReceiverFrequencySelection............................................................................2–7
2.6 RFConnections .................................................................................................2–9
2.7 AudioInputConnections .................................................................................2–10
2.8 SCAInputConnections ...................................................................................2–11
2.9 CompositeInputConnection ...........................................................................2–11
2.10 AudioMonitorConnections.............................................................................2–12
2.11 Pre-emphasisSelection...................................................................................2–12
2.12 ProcessorBypassOption ................................................................................2–12
2.13 ProgramInputFaultTime-out .........................................................................2–13
2.14 RemoteI/OConnector.....................................................................................2–13

iv
Section 3—Operation................................................. 3–1
3.1 InitialPower-upProcedures ..............................................................................3–2
3.2 PowerSwitches.................................................................................................3–4
3.2.1 DCBreaker....................................................................................................3–4
3.2.2 PowerSwitch................................................................................................3–4
3.2.3 CarrierSwitch ...............................................................................................3–4
3.3 FrontPanelBar-Dot Displays.............................................................................3–5
3.3.1 AudioProcessorInput ..................................................................................3–5
3.3.2 Highbandand WidebandDisplay ..................................................................3–5
3.3.3 ModulationDisplay .......................................................................................3–5
3.5 ProcessingControl............................................................................................3–6
3.6 Stereo-MonoSwitch..........................................................................................3–6
3.4 InputGainSwitches ..........................................................................................3–6
3.7 RF Output Control .............................................................................................3–7
3.8 DigitalMultimeter..............................................................................................3–7
3.9 FaultIndicators .................................................................................................3–8
Section 4—Principles of Operation................................. 4–1
4.1 PartNumbering.................................................................................................4–2
4.2 AudioProcessorCircuitBoard ..........................................................................4–3
4.3 StereoGeneratorCircuitBoard..........................................................................4–4
4.4 RF Exciter Circuit Board ....................................................................................4–6
4.5 MeteringCircuitBoard ......................................................................................4–8
4.6 Motherboard .....................................................................................................4–9
4.7 DisplayCircuitBoard.......................................................................................4–10
4.8 VoltageRegulatorCircuitBoard ......................................................................4–11
4.9 PowerRegulatorCircuitBoards ......................................................................4–12
4.10 RF Driver.........................................................................................................4–12
4.11 RFAmplifier ....................................................................................................4–13
4.12 Chassis ...........................................................................................................4–13
4.13 RF Output Filter & Reflectometer.....................................................................4–14
4.15 ReceiverCircuitBoardOption .........................................................................4–14

v
Section 5—Adjustments and Tests ................................. 5–1
5.1 AudioProcessorAdjustments ...........................................................................5–2
5.1.1 Pre-EmphasisSelection ................................................................................5–2
5.1.2 Pre-EmphasisFineAdjustment .....................................................................5–2
5.2 StereoGeneratorAdjustments ..........................................................................5–3
5.2.1 Separation ....................................................................................................5–3
5.2.2 CompositeOutput.........................................................................................5–3
5.2.3 19 kHz Level .................................................................................................5–3
5.2.4 19 kHz Phase................................................................................................5–3
5.3 FrequencySynthesizerAdjustments ..................................................................5–4
5.3.1 Frequency(Channel)Selection......................................................................5–4
5.3.2 ModulationCompensator..............................................................................5–4
5.3.3 FrequencyMeasurementandAdjustment .....................................................5–4
5.3.4 FSKBalance Control .....................................................................................5–4
5.4 MeteringBoardAdjustments.............................................................................5–5
5.4.1 PowerCalibrate.............................................................................................5–5
5.4.2 PowerSet .....................................................................................................5–5
5.4.3 SWRCalibrate...............................................................................................5–5
5.4.4 PACurrentLimit ...........................................................................................5–5
5.5 MotherboardAdjustments.................................................................................5–6
5.6 DisplayModulationCalibration..........................................................................5–6
5.7 VoltageRegulatorAdjustments .........................................................................5–6
5.8 Bias Set (RF Power Amplifier)...........................................................................5–6
5.9 PerformanceVerification ...................................................................................5–7
5.9.1 AudioProof-of-PerformanceMeasurements.................................................5–7
5.9.2 De-emphasisInputNetwork..........................................................................5–7
5.10 CarrierFrequency ..............................................................................................5–8
5.11 OutputPower ....................................................................................................5–8
5.12 RF Bandwidth and RF Harmonics......................................................................5–8
5.13 PilotFrequency .................................................................................................5–8
5.14 AudioFrequencyResponse ...............................................................................5–9
5.15 AudioDistortion ................................................................................................5–9
5.16 ModulationPercentage......................................................................................5–9
5.17 FM and AM Noise..............................................................................................5–9
5.18 StereoSeparation..............................................................................................5–9
5.19 Crosstalk ...........................................................................................................5–9
5.19.1 Main Channel Into Sub ..............................................................................5–10
5.19.2 Sub Channel Into Main ..............................................................................5–10
5.20 38kHzSubcarrierSuppression.......................................................................5–10
5.21 AdditionalChecks............................................................................................5–10

Section 6—Reference Drawings .................................... 6–1
6.1 Views ................................................................................................................6–2
6.2 BoardLayoutsandSchematics .........................................................................6–4
Section 7—Service and Support.................................... 7–1
7.1 Service ..............................................................................................................7–2
7.2 24–HourSupport ..............................................................................................7–2
7.3 SpareParts .......................................................................................................7–2
Appendix................................................................A–1
Glossary.................................................................G–1
Index................................................................Index–1

1–1
Getting Acquainted
Section 1—Getting Acquainted
This section provides a general description of the FM500 trans-
mitter and introduces you to safety conventions used within this
document. Review this material before installing or operating
the transmitter.
I
INFORMATION

1–2 FM500 User's Manual
I
1.1 Your Transmitter
The FM500 is a member of a family of FM stereo broadcast transmitters. Crown
transmitters are known for their modularity, ease-of-use, and reliability.
The modularity is most apparent in the standard transmitter configuration which
incorporates audio processing, stereo generation, and RF amplification without
compromised signal quality. A single Crown transmitter can replace several pieces
of equipment in a traditional system.
Ease-of-use is apparent in the user-friendly front panel interface and in the instal-
lation procedure. Simply select your operating frequency (using four rotary
switches), add an audio source, attach an antenna, connect AC power, and you're
ready to broadcast. Of course, the FM series of transmitters also feature more
sophisticated inputs and monitoring connections if needed.
Reliability is a Crown tradition. The first Crown transmitters were designed for
rigors of worldwide and potentially portable use. The modular design, quality
components, engineering approach, and high production standards ensure stable
performance.
Remote control and metering of the transmitter is made possible through a built-
in I/O port. For more direct monitoring, the front panel includes a digital multi-
meter display and status indicators. Automatic control circuitry provides protec-
tion for high VSWR as well as high current, voltage, and temperature conditions.
Illustration 1–1 FM500 Stereo Broadcast Transmitter
FM500
FM BROADCAST TRANSMITTER
®
Power
Carrier
Modulation
Fault
Stereo
Mono RF Output
ProcessingInput Gain
Wide Band
High Band
Audio Input
High
Low
2
-6
-12
-18
2
+6 dB +12 dB
10
20
Expand Compress
RF Power
SWR
ALC
PA DC Volts
PA DC Amps
PA Temperature
Supply DC Volts
Voltmeter
SWR
Lock
Input
PA DC
PA Temp
Over
100
90
80
70
60
50
40
30
20
Pilot

1–3
Getting Acquainted
1.2 Applications and Options
Crown transmitters are designed for versatility in applications. They have been used
as stand-alone and backup transmitters and in booster, translator, and satellator
applications. The following discussion describes these applications further.
Model numbers describe the configuration of the product (which has to do with its
intended purpose) and the RF output power which you can expect.
The number portion of each name represents the maximum RF output power. The
FM500, for example, can generate up to 500 watts of RF output power.
Suffix letters describe the configuration. The FM500T, for example, designates a
"transmitter" configuration. Since this is standard, it is what is described in the
manual except where specified. In this configuration, the product includes the
following modules (functions):
❑audio processor
❑stereo generator
❑RF exciter
❑metering
❑low-pass filter
Illustration 1–2 Standard (Transmitter) Configuration
RF Exciter
Metering
Low-pass Filter
Stereo Generator
Audio Processor
FM500
FM BROADCAST TRANSMITTER
®
Power
Carrier
Modulation
Fault
Stereo
Mono RF Output
ProcessingInput Gain
Wide Band
High Band
Audio Input
High
Low
2
-6
-12
-18
2
+6 dB +12 dB
10
20
Expand Compress
RF Power
SWR
ALC
PA DC Volts
PA DC Amps
PA Temperature
Supply DC Volts
Voltmeter
SWR
Lock
Input
PA DC
PA Temp
Over
100
90
80
70
60
50
40
30
20
Pilot

1–4 FM500 User's Manual
I
1.2.1 Stand-Alone
In the standard configuration, the FM500 is an ideal stand-alone transmitter.
When you add an audio source (monaural, L/R stereo, or composite signal), an
antenna, and AC power, the transmitter becomes a complete FM stereo broadcast
station, capable of serving a community.
As stand-alone transmitters, Crown units often replace multiple pieces of equip-
ment in a traditional setup (exciter, audio processor, RF amplifier).
1.2.2 Backup
In the standard configuration, Crown transmitters are also used in backup applica-
tions. Should your primary transmitter become disabled, you can continue to
broadcast while repairs take place. In addition, the FM transmitters can replace
disabled portions of your existing system including the exciter, audio processor, or
amplifier. Transfer switches on each side of the existing and backup transmitters
make the change-over possible with minimal downtime.
1.2.3 Booster
Also in the standard configuration, Crown transmitters have been used as booster
transmitters. Booster applications typically involve certain geographic factors
which prevent your system from broadcasting to the full coverage area allowable.
For example, a mountain range might block your signal to a portion of your
coverage area. Careful placement of a Crown transmitter, operating on the same
frequency as your primary transmitter, can help you reach full coverage.
1.2.4 Exciter
In addition to the standard configuration, the FM500 is available in optional
configurations to meet a variety of needs.
An "E" suffix, as in the FM500E, for example, represents an exciter-only configura-
tion. In this configuration, the audio processor and stereo generator are not
included. The exciter configurations are the least expensive way to get Crown-
quality components into your transmission system.
You might consider the Crown exciter when other portions of your system are
performing satisfactorily and you want to maximize your investment in present
equipment.