Crown FMX30, FMX100, FMX250 User Manual

©2003 Crown Broadcast, a division of International Radio and Electronics, Inc.

25166 Leer Drive, Elkhart, Indiana, 46514-5425 U.S.A.

[phone]

Rev. 1.0

Revision Print Date

Rev. 1.0 January 2003

©2002, 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 International Radio and
Electronics, Inc.

Printed in U.S.A.
Sony and RCA are trademarks of their respective companies.
IREC attempts to provide information that is accurate, complete, and useful. Should

you find inadequacies in the text, please send your comments to the following
address:

ii

FMX30/FMX100/FMX250 User’s Manual

Rev. 1.0

Table of Contents

Table of Contents iii

Section 1—Getting Acquainted

1.1 Your Transmitter .........................................................................................1-2

1.2 Applications and Options.............................................................................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

1.2.7 Nearcasting.............................................................................................1-6

1.3 Transmitter/Exciter Specifications...............................................................1-7

1.4 Receiver Specifications................................................................................1-9

1.5 Safety Considerations................................................................................1-10

1.5.1 Dangers.................................................................................................1-10

1.5.2 Warnings...............................................................................................1-10

1.5.3 Cautions................................................................................................1-10

Section 2—Installation

2.1 Operating Location......................................................................................2-2

2.2 Power Connections......................................................................................2-2

2.2.1 AC Line Voltage Setting...........................................................................2-2

2.2.2 Fuses.......................................................................................................2-4

2.3 Frequency (Channel) Selection....................................................................2-5

2.3.1 Modulation Compensator........................................................................2-5

2.3.2 RF Tuning Adjustments...........................................................................2-5

2.4 Receiver Frequency Selection......................................................................2-6

2.5 RF Connections ...........................................................................................2-8

2.6 Audio Input Connections.............................................................................2-9

2.7 SCA Input Connections..............................................................................2-11

2.8 Composite Input Connection.....................................................................2-11

2.9 Audio Monitor Connections.......................................................................2-12

2.10 Pre-emphasis Selection.............................................................................2-12

2.11 Processor Bypass Option ..........................................................................2-12

2.12 Program Input Fault Time-out ...................................................................2-13

2.13 Remote I/O Connector...............................................................................2-14

Section 3—Operation

3.1 Initial Power-up Procedures........................................................................3-2

3.2 Controls and Display....................................................................................3-2

3.2.1 Front Panel..............................................................................................3-2

3.2.2 DC Breaker..............................................................................................3-4

3.3 Operating the FMX.......................................................................................3-4

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Rev. 1.0

3.3.1 Passwords...............................................................................................3-4

3.3.2 Main Function List...................................................................................3-4

3.3.3 Readings Function List............................................................................3-5

3.3.4 Settings Function List..............................................................................3-6

3.3.5 Factory Setting Functions........................................................................3-7

3.3.6 Audio Monitor.........................................................................................3-7

3.3.7 Fault Log.................................................................................................3-7

3.4 Power-up procedure....................................................................................3-8

3.4.1 Apply Power............................................................................................3-8

3.4.2 Enter Initial Settings................................................................................3-8

3.4.3 Transmit..................................................................................................3-8

Section 4—Principles of Operation

4.1 Block Diagram.............................................................................................4-2

4.2 Audio Processor Circuit Board.....................................................................4-3

4.2.1 Balanced Input ........................................................................................4-3

4.2.2 Audio Processor......................................................................................4-3

4.3 Stereo Generator Circuit Board....................................................................4-4

4.3.1 Low-pass filter ........................................................................................4-4

4.3.2 Stereo Generator.....................................................................................4-5

4.3.3 SCA Input................................................................................................4-5

4.3.4 Processed Audio.....................................................................................4-5

4.4 RF Exciter Circuit Board...............................................................................4-6

4.5 Digital Management System........................................................................4-7

4.5.1 Metering Boards......................................................................................4-7

4.5.2 Front Panel..............................................................................................4-7

4.6 Motherboard................................................................................................4-8

4.7 Voltage Regulator Circuit Board...................................................................4-8

4.8 Power Regulator Circuit Board ....................................................................4-9

4.9 RF Driver/Amplifier (FM30)..........................................................................4-9

4.10 RF Driver (FM100/FM250)...........................................................................4-9

4.11 RF Amplifier (FM100/FM250)......................................................................4-9

4.12 Chassis......................................................................................................4-10

4.13 RF Output Filter & Reflectometer...............................................................4-11

4.14 Receiver Circuit Board Option....................................................................4-11

Section 5—Service and Support

5.1 Service.........................................................................................................4-2

5.2 24–Hour Support.........................................................................................4-2

5.3 Spare Parts..................................................................................................4-2

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FMX30/FMX100/FMX250 User’s Manual

Rev. 1.0

I

INFORMATION

This section provides a general description of the FMX30,
FMX100, and FMX250 transmitters and introduces you to safety
conventions used within this document.Review this material
before installing or operating the transmitter.

Getting Acquainted 1—1

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Rev. 1.0

The FMX30, FMX100, and FMX250 are members of a family of FM stereo broadcast
transmitters. Crown transmitters are known for their integration, ease-of-use, and
reliability.

The integration 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
installation procedure. Simply select your operating frequency add an audio source,
attach an antenna, and connect AC or DC 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. For more direct monitoring, the front panel includes a single control
knob, a four line display and bar graph indicators. Automatic control circuitry
provides protection for high VSWR as well as high current, voltage, and
temperature conditions.

This manual describes the FMX30, FMX100, and FMX250
Because all three transmitters share common design factors. Specific product
differences are noted throughout the manual. In physical appearance, the
FMX30 differs from the FMX100 and FMX250 in that it lacks the power amplifier
and cooling fan assembly on the back panel.

1—2

Illustration 1–1 FMX250 FM Broadcast Transmitter

FMX30/FMX100/FMX250 User’s Manual

Rev. 1.0

Crown transmitters are designed for versatility in applications. They have been used
as stand-alone and backup transmitters and in booster, translator, satellator, and
nearcast 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
FMX250, for example, can generate up to 250 watts of RF output power.

Suffix letters describe the configuration. The FMX250T, for example, is the standard
or transmitter configuration. Except where specified, this document describes the
transmitter configuration. In this configuration, the product includes the following
components (functions):

• audio processor

• stereo generator

• RF exciter

• metering

• low-pass filter

Stereo
Generator

Audio
Processor

RF Exciter

Low-Pass
Filtering

Metering

Illustration 1–2 Standard (Transmitter) Configuration

Getting Acquainted 1—3

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Rev. 1.0

1.2.1 Stand-Alone

In the standard configuration, the FMX30, FMX100, and FMX250 are ideal stand­alone transmitters. When you add an audio source (monaural, L/R stereo, or
composite signal), an antenna, and AC or DC 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
equipment in a traditional setup (exciter, audio processor, RF amplifier).

1.2.2 Backup

In the standard configuration, Crown transmitters are also used in backup
applications. 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.

The DC operation option of the FMX30, FMX100, and FMX250 make them attractive
backup units for those times when AC power is lost.

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. An external receiver and
special antenna are required to use Crown FM transmitters as boosters.

1.2.4 Exciter

In addition to the standard configuration, Crown FM transmitters are available in
optional configurations to meet a variety of needs.

An “E” suffix, as in the FMX30E, for example, represents an exciter-only
configuration. In this configuration, the audio processor and stereo generator
boards are replaced with circuitry to bypass their function. 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.

1—4

FMX30/FMX100/FMX250 User’s Manual

Rev. 1.0

1.2.5 Translator

The FMX30R receiver option replaces the audio processor and stereo generator
boards with a receiver module. This added feature makes Crown transmitters ideal
for translator service in terrestrial-fed networks. These networks represent a
popular and effective way to increase your broadcasting coverage. Translators,
acting as repeater emitters, are necessary links in this chain of events.

Traditionally, network engineers have relied on multiple steps and multiple pieces of
equipment to accomplish the task. Others have integrated the translator function
(receiver and exciter) to feed an amplifier. Crown, on the other hand, starts with an
integrated transmitter and adds a solid-state Receiver Module to form the ideal
translator.

Receiver
Module

RF In Low-Pass

Filter

RF Out

(Option)

RF Exciter

Metering

Illustration 1–3 Crown’s Integrated Translator

This option enables RF in and RF out on any of Crown’s FM series of transmitters.
In addition, the module supplies a composite output to the RF exciter portion of the
transmitter. From here, the signal is brought to full power by the built-in power
amplifier for retransmission. The Receiver Module has been specifically designed to
handle SCA channel output up to 100 kHz for audio and high-speed data.

FSK ID programming is built-in to ensure compliance with FCC regulations
regarding the on-air identification of translators. Simply specify the call sign of the
repeater station when ordering. Should you need to change the location of the
translator, replacement FSK chips are available. The Receiver Module option should
be ordered at the time of initial transmitter purchase. However, an option kit is
available for field converting existing Crown units.

In the translator configuration there are differences in the function of the front
panel, See Section 3.7, Digital Multimeter for a description.

Getting Acquainted 1—5

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Rev. 1.0

1.2.6 Satellator

Crown transmitters include automatic call sign or operating frequency
transmission in a Morse code style. This feature is intended for use in satellite-fed
networks. Transmitters equipped in this fashion are often known as “satellators.”

Connect the transmitter to your satellite receiver and the built-in FSK IDer does the
rest—shifting the frequency to comply with FCC requirements and in a manner
that is unnoticeable to the listener.

1.2.7 Nearcasting

Some Crown units function as “nearcast” transmitters. Their low-power output is
not designed for broadcasting a signal but for transmitting it to local receivers,
sometimes within the same room. Crown transmitters have been used in this way
for language translation, for rebroadcasting the audio of sporting events within a
stadium, and for specialized local radio. Crown makes a dedicated nearcast
transmitter. However, the FMX30 is also appropriate for this application.

1—6

FMX30/FMX100/FMX250 User’s Manual

Rev. 1.0

=

Frequency Range 87.9 -107.9 MHz

RF Power Output

FMX30
FMX100
FMX250

(VSWR 1.5:1 or better)
3-30 watts, adjustable

10-100 watts, adjustable

20-250 watts, adjustable
RF Output Impedance 50Ω
Frequency Stability Meets FCC specifications from 0-50

degrees C
Audio Input Impedance 50 kΩ bridging, balanced, or 600 Ω
Audio Input Level Selectable for -10 dBm to +10 dBm for

75 kHz deviation at 400 Hz
Pre-emphasis Selectable for 25, 50, or 75 µsec; or Flat
Audio Response Conforms to 75 µsec pre-emphasis curve

as follows

Complete transmitter ±0.30 dB (50 Hz-10 kHz)

±1.0 dB (10 kHz-15 kHz)

Exciter only ±0.25 dB (50 Hz-15 kHz

Distortion (THD + Noise)

Complete transmitter Less than 0.7% (at 15 kHz)
Exciter only Less than 0.3% (50 Hz-15 kHz)

Stereo Separation

Complete transmitter Better than -40 dB (50 Hz-15 kHz)
Exciter only Better than -40 dB (50 Hz-15 kHz)

Crosstalk Main into sub, better than -40 dB

Sub into main, better than -40 dB
Stereo Pilot 19 kHz ±2 Hz, 9% modulation
Subcarrier Suppression 50 dB below ±75 kHz deviation
FM S/N Ratio (FM noise)

Complete transmitter Better than -60 dB
Exciter only Better than -70 dB

Getting Acquainted 1—7

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Rev. 1.0

AM S/N Ratio Asynchronous and synchronous noise

better than FCC requirements
RF Bandwidth ±120 kHz, better than -35 dB
±240 kHz, better than -45 dB
RF Spurious Products Better than -70 dB
Operating Environment

AC Power

FMX30
FMX100
FMX250

DC Power

FMX30
FMX100

FMX250

Note: Note: We set voltage and ampere requirements to assist you in

designing your system. Depending on your operating frequency,
actual requirements for maximum voltage and current readings are
10-15% lower than stated.

Temperature (0o C -50o C)

Humidity (0-80% at 20o C)

Maximum Altitude (3,000 meters; 9843

feet)

100, 120, 220, or 240 volts (+10%/15%);

50/60 Hz

115 VA

297 VA

550 VA

24-36 volts (36 volts at 3 amps required

for full output power)

36-62 volts (48 volts at 5 amps required

for full output power)

36-62 volts (72 volts at 8 amps required

for full output power)

Regulatory Type notified for FCC parts 73 and 74

Dimensions 13.5 x 41.9 x 44.5 cm

Weight

FMX30
FMX100
FMX250

1—8

Meets FCC, DOC, and CCIR

requirements

(5.25 x 16.5 x 17.5 inches)

10.5 kg (23 lbs)

13.6 kg (30 lbs) shipping weight

11.4 kg (25 lbs)

14.5 kg (32 lbs) shipping weight

16.8 kg (37 lbs)20.0 kg (44 lbs) shipping

weight

FMX30/FMX100/FMX250 User’s Manual

Rev. 1.0

Monaural Sensitivity

3.5µV for signal-to-noise > 50 dB

(demodulated, de-emphasized)

12.6µV for signal-to-noise > 60 dB

Stereo Sensitivity

2.8µV for signal-to-noise > 40 dB

(19–kHz pilot frequency added)

8µV for signal-to-noise > 50 dB

31µV for signal-to-noise > 60 dB
Connector Standard type N, 50 Ω
Shipping Weight 1 lb

Getting Acquainted 1—9

I

Rev. 1.0

Crown Broadcast assumes the responsibility for providing you a safe product and
safety guidelines during its use. “Safety” means protection to all individuals who
install, operate, and service the transmitter as well as protection of the transmitter
itself. To promote safety, we use standard hazard alert labeling on the product and
in this manual. Follow the associated guidelines to avoid potential hazard.

1.5.1 Dangers

DANGER represents the most severe hazard alert. Extreme bodily harm or death
will occur if DANGER guidelines are not followed.

1.5.2 Warnings

WARNING represents hazards which could result in severe injury or death.

1.5.3 Cautions

CAUTION indicates potential personal injury, or equipment or property damage if
the associated guidelines are not followed. Particular cautions in this text also
indicate unauthorized radio-frequency operation.

Pictorial or
written
description
of hazard

Severity of
hazard

DANGER

Sever shock hazard!
Turn power off and wait

approximtely 1 minute for
capcitors to discharge
before handling them.

Explanation of

hazard

Illustration 1–4 Hazard Warning

1—10

FMX30/FMX100/FMX250 User’s Manual

This section provides important guidelines for installing your
transmitter. Review this information carefully for proper
installation.

Installation 2—1

Rev. 1.0

CAUTION

Possible equipment damage!
Before operating the transmitter for the first

time, check for the proper AC line voltage set­ting and frequency described in Section 2.2,
Power Connections and Section 2.3, Frequency
(Channel) Selection.

You can install the FM transmitter in a standard component rack or on a suitable
surface such as a bench or desk. In any case, the area should be as clean and well­ventilated as possible. Always allow for at least 2 cm of clearance under the unit for
ventilation. If you set the transmitter on a flat surface, install spacers on the bottom
cover plate. If you install the transmitter in a rack, provide adequate clearance above
and below. Do not locate the transmitter directly above a hot piece of equipment.

The FMX30, FMX100, and FMX250 operate on 100, 120, 220, or 240 volts AC (50 or
60 Hz; single phase). Each transmitter can operate on DC power as well (28 volts
for the FMX30, 36 volts for the FMX100, and 62 volts for the FMX250). The
transmitter can operate on lower DC voltage, but with reduced RF output power
(see section 1.2). In addition, the transmitter isolates the AC and DC sources; both
can be connected at the same time to provide battery backup in the event of an AC
power failure.

2.2.1 AC Line Voltage Setting

To change the voltage setting, follow these steps:

1. Disconnect the power cord if it is attached.

2. Open the cover of the power connector assembly using a small, flat blade
screwdriver. See Illustration 2–1, Removing the Power Connector Cover.

3. Insert the screwdriver into the voltage selection slot and remove the drum
from the assembly.

4. Rotate the drum to select the desired voltage. See Section 2.2, Power Connec­tions.

5. Replace the drum and cover and check to see that the correct voltage appears
in the connector window.

6. Connect the AC power cord.

2—2

FMX30/FMX100/FMX250 User’s Manual

120 Vac

Rev. 1.0

Illustration 2–1 Removing the Power Connector Cover

120Vac
220Vac

240Vac

Installation 2—3

Illustration 2–2 Selecting an AC Line Voltage