Broadcast Electronics FX-50 User manual

Broadcast Electronics
4100 North 24th Street, Quincy, Illinois 62305 USA • Phone [phone] • Fax [phone] • www.bdcast.com • [e-mail]
FX-50, FX-50E
50 WATT
FM Exciter
Instruction Manual
597-1050
Rev B
December 15, 2011

FX-50, FX-50E. 50 WATT FM Exciter
Instruction Manual
©2011 Broadcast Electronics. All rights reserved.
The information in this publication is subject to improvement and change without notice. Although
every effort is made to ensure the accuracy of the information in this manual, Broadcast Electronics
accepts no responsibility for any errors or omissions. Broadcast Electronics reserves the right to
modify and improve the design and specifications of the equipment in this manual without notice.
Any modifications shall not adversely affect performance of the equipment so modified.
Proprietary Notice
This document contains proprietary data of Broadcast Electronics Inc. No part of this publication may
be reproduced, transmitted, transcribed, stored in a retrieval system, translated into any other
language in any form or by any means, electronic or mechanical, including photocopying or
recording, for any purpose, without the express written permission of Broadcast Electronics.
Trademarks
Broadcast Electronics and the BE logo are registered trademarks of Broadcast Electronics.
All other trademarks are property of their respective owners.

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Broadcast Electronics
Product Warranty (Two-Year Limited)
BE hereby warrants all new products manufactured by BE against any defects in material or
workmanship at the time of delivery thereof, or that develop under normal use within a period of
two (2) years from the date of shipment.
BE reserves the right to repair equipment under warranty with new or refurbished equipment or
parts. BE’s sole responsibility with respect to any equipment or parts not conforming to this
warranty is to replace or repair such equipment upon the return thereof F.O.B. to BE’s factory in
Quincy, Illinois, U.S.A. In the event of replacement pursuant to the foregoing warranty, only the
unexpired portion of the warranty from the time of the original purchase will remain in effect for
any such replacement.
This warranty shall exclude the following products, component parts and/or assemblies:
(a) Transmitter power output tubes shall only carry the original manufacturers’ or suppliers’
standard warranty in effect on their original shipment date.
(b) All computers, computer peripherals, cables, hard disk drives, etc., shall only carry the
manufacturers’ or suppliers’ standard warranty in effect on their original shipment date.
(c) “Components”, defined as separate and individual parts (e.g. transistors, integrated
circuits, capacitors, resistors, inductors, fans, etc), resold by BE from another manufacturer
or supplier, shall only carry a 90 day warranty, effective the date of shipment. Any such
‘Components’ being returned for warranty claim must be (1) returned in their original
packaging and (2) must be in new, unused condition.
BE is unable to process or resolve component defects or performance concerns on
components that have been soldered, installed, wired or in any way altered from new their
new condition.
(d) “Resale Equipment”, defined as equipment purchased from another manufacturer or
supplier, then resold by BE, shall only carry such manufacturers’ or suppliers’ standard
warranty in effect as of the original shipment date. All warranty claims against any and all
‘resale equipment’ sold by BE must be filed directly with the original equipment
manufacturer. BE is unable to process or resolve equipment defects or performance
concerns on products or services not manufactured by BE.
This warranty shall not extend to claims resulting from any acts of God, terrorism, war, defects or
failures caused by Purchaser or user abuse or misuse, operator error, or unauthorized attempts to
repair or alter the equipment in any way.
Under no circumstances shall BE be responsible for indirect, incidental or consequential damages,
including, but not limited to transportation costs, non-authorized repair or service costs, downtime
costs, costs for substituting equipment or loss of anticipated profits or revenue incurred by
Purchaser, whether based in contract, tort or for negligence or breach of statutory duty or
otherwise.
The terms of the foregoing warranty shall be null and void if the equipment has been altered or
repaired without specific written authorization from BE, or if not installed according to BE’s
instruction manuals including, but not limited to, the absence of proper grounding, surge (TVSS)
protection on the AC circuit panel or proper lightning protection/grounding on all output circuits,
or if equipment is operated under environmental conditions or circumstances other than those
specifically described in BE’s product literature or instruction manual which accompany the
equipment. The warranty shall be voided if the product or subassembly is equipped with a tamper
seal and that tamper seal is broken. BE shall not be liable for any expense of any nature
whatsoever incurred by the original user without prior written consent of BE.

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The warranty provided herein shall terminate at the end of the period set forth above. This
warranty extends only to the original Purchaser and is not transferable. There are no third party
beneficiaries of any of the provisions of this warranty. If the equipment is described as “used”
equipment, it is sold as is and where is and no warranty applies unless authorized in writing.
EXCEPT AS SET FORTH HEREIN, AS TO TITLE AND AS SPECIFICALLY REQUIRED BY LAW, THERE ARE
NO OTHER WARRANTIES, OR ANY AFFIRMATIONS OF FACT OR PROMISES BY BE, WITH REFERENCE
TO THE EQUIPMENT, OR TO MERCHANTABILITY, FITNESS FOR A PARTICULAR APPLICATION,
SIGNAL COVERAGE, INFRINGEMENT, OR OTHERWISE, WHICH EXTEND BEYOND THE DESCRIPTION
OF THE EQUIPMENT ON THE FACE HEREOF.

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IMPORTANT INFORMATION
EQUIPMENT LOST OR DAMAGED IN TRANSIT -
When delivering the equipment to you, the truck driver or carriers’ agent will present a receipt for
your signature. Do not sign it until you have:
1) Inspected the containers for visible signs of damage and 2) Counted the containers and
compared with the amount shown on the shipping papers. If a shortage or evidence of damage is
noted, insist that notation to that effect be made on the shipping papers before you sign them.
Further, after receiving the equipment, unpack it and inspect thoroughly for concealed damage. If
concealed damage is discovered, immediately notify the carrier, confirming the notification in
writing, and secure an inspection report. This item should be unpacked and inspected for damage
WITHIN 15 DAYS after receipt. Claims for loss or damage will not be honored without proper
notification of inspection by the carrier.
RF PRODUCT TECHNICAL ASSISTANCE, REPAIR SERVICE, PARTS -
Technical assistance is available from Broadcast Electronics by letter, prepaid telephone or E-mail.
Equipment requiring repair or overhaul should be sent by common carrier, prepaid, insured, and
well protected. If proper shipping materials are not available, contact the RF Technical Services
Department for a shipping container. Do not mail the equipment. We can assume no liability for
inbound damage, and necessary repairs become the obligation of the shipper. Prior arrangement
is necessary. Contact the RF Technical Services Department for a Return Authorization.
Emergency and warranty replacement parts may be ordered from the following address. Be sure
to include the equipment model number, serial number, part description, and part number. Non-
emergency replacement parts may be ordered directly from the Broadcast Electronics stock room
at the number shown below.
RF TECHNICAL SERVICES -
Telephone: [phone]
E-Mail: [email protected]
Fax: [phone]
FACILITY CONTACTS -
Broadcast Electronics, Quincy Facility
4100 N. 24th St. P.O. BOX 3606
Quincy, Illinois 62305
Telephone: [phone]
Fax: [phone]
General E-Mail: [email protected]
Web Site: www.bdcast.com
PARTS -
Telephone: [phone]
E-Mail: [e-mail]

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RETURN, REPAIR, AND EXCHANGES -
Do not return any merchandise without our written approval and Return Authorization. We will
provide special shipping instructions and a code number that will assure proper handling and
prompt issuance of credit. Please furnish complete details as to circumstances and reasons when
requesting return of merchandise. All returned merchandise must be sent freight prepaid and
properly insured by the customer.
MODIFICATIONS -
Broadcast Electronics, reserves the right to modify the design and specifications of the equipment
in this manual without notice. Any modifications shall not adversely affect performance of the
equipment so modified.

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SAFETY PRECAUTIONS
PLEASE READ AND OBSERVE ALL SAFETY PRECAUTIONS//
ALL PERSONS WHO WORK WITH OR ARE EXPOSED TO POWER TUBES, POWER
TRANSISTORS, OR EQUIPMENT WHICH UTILIZES SUCH DEVICES MUST TAKE
PRECAUTIONS TO PROTECT THEMSELVES AGAINST POSSIBLE SERIOUS BODILY INJURY.
EXERCISE EXTREME CARE AROUND SUCH PRODUCTS. UNINFORMED OR CARELESS
OPERATION OF THESE DEVICES CAN RESULT IN POOR PERFORMANCE, DAMAGE TO THE
DEVICE OR PROPERTY, SERIOUS BODILY INJURY, AND POSSIBLY DEATH.
DANGEROUS HAZARDS EXIST IN THE OPERATION OF POWER TUBES AND
POWER TRANSISTORS -
The operation of power tubes and power transistors involves one or more of the following
hazards, any one of which, in the absence of safe operating practices and precautions, could
result in serious harm to personnel.
A. HIGH VOLTAGE Normal operating voltages can be deadly. Additional information
follows.
B. RF RADIATION Exposure to RF radiation may cause serious bodily injury possibly
resulting in Blindness or death. Cardiac pacemakers may be affected. Additional
information follows.
C. HOT SURFACES Surfaces of air-cooled radiators and other parts of tubes can reach
temperatures of several hundred degrees centigrade and cause serious burns if
touched. Additional information follows.
D. RF BURNS Circuit boards with RF power transistors contain high RF potentials. Do not
operate an RF power module with the cover removed.

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HIGH VOLTAGE –
Many power circuits operate at voltages high enough to kill through electrocution. Personnel
should always break the primary AC Power when accessing the inside of the transmitter.
RADIO FREQUENCY RADIATION
Exposure of personnel to RF radiation should be minimized, personnel should not be permitted in
the vicinity of open energized RF generating circuits, or RF transmission systems (waveguides,
cables, connectors, etc.), or energized antennas. It is generally accepted that exposure to “high
levels” of radiation can result in severe bodily injury including blindness. Cardiac pacemakers may
be affected.
The effect of prolonged exposure to “low level” RF radiation continues to be a subject of
investigation and controversy. It is generally agreed that prolonged exposure of personnel to RF
radiation should be limited to an absolute minimum. It is also generally agreed that exposure
should be reduced in working areas where personnel heat load is above normal. A 10 mW/cm2
per one tenth hour average level has been adopted by several U.S. Government agencies
including the Occupational Safety and Health Administration (OSHA) as the standard protection
guide for employee work environments. An even stricter standard is recommended by the
American National Standards Institute which recommends a 1.0 mW/cm2 per one tenth hour
average level exposure between 30 Hz and 300 MHz as the standard employee protection guide
(ANSI C95.1-1982).
RF energy must be contained properly by shielding and transmission lines. All input and output RF
connections, such as cables, flanges and gaskets must be RF leak proof. Never operate a power
tube without a properly matched RF energy absorbing load attached. Never look into or expose
any part of the body to an antenna or open RF generating tube or circuit or RF transmission
system while energized. Monitor the tube and RF system for RF radiation leakage at regular
intervals and after servicing.
HOT SURFACES –
The power components in the transmitter are cooled by forced-air and natural convection. When
handling any components of the transmitter after it has been in operation, caution must always
be taken to ensure that the component is cool enough to handle without injury.

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Table of Contents
1OVERVIEW......................................................................................................................................1
1.1 RELATED PUBLICATIONS................................................................................................................... 1
1.2 EQUIPMENT DESCRIPTION................................................................................................................ 1
1.3 FX-50 AND FX-50E MODELS. ........................................................................................................... 2
1.4 PHYSICAL DESCRIPTION.................................................................................................................... 2
1.5 ELECTRICAL DESCRIPTION. ............................................................................................................... 2
1.6 EQUIPMENT SPECIFICATIONS. .......................................................................................................... 3
2INSTALLATION ................................................................................................................................7
2.1 UNPACKING. .................................................................................................................................... 7
2.2 INSTALLATION.................................................................................................................................. 7
2.3 WIRING. ......................................................................................................................................... 12
2.4 EXCITER CHECKOUT. ...................................................................................................................... 14
3OPERATION. .................................................................................................................................17
3.1 CONTROLS AND INDICATORS......................................................................................................... 17
3.2 OPERATION.................................................................................................................................... 17
4THEORY OF OPERATION................................................................................................................21
4.1 FUNCTIONAL DESCRIPTION. ........................................................................................................... 21
5MAINTENANCE.............................................................................................................................25
5.1 SAFETY CONSIDERATIONS.............................................................................................................. 25
5.2 FIRST LEVEL MAINTENANCE. .......................................................................................................... 25
5.3 SECOND LEVEL MAINTENANCE. ..................................................................................................... 25
5.4 TROUBLESHOOTING....................................................................................................................... 26
6POWER SUPPLY/CONTROL CIRCUIT ...............................................................................................31
6.1 DESCRIPTION.................................................................................................................................. 31
6.2 ELECTRICAL CHARACTERISTICS. ...................................................................................................... 31
6.3 REMOVAL AND INSTALLATION....................................................................................................... 32
6.4 THEORY OF OPERATION ................................................................................................................. 32
6.5 MAINTENANCE .............................................................................................................................. 38

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7EXCITER METERING CIRCUIT BOARD ............................................................................................45
7.1 DESCRIPTION.................................................................................................................................. 45
7.2 INTERNAL VOLTMETER CHARACTERISTICS...................................................................................... 45
7.3 REMOVAL AND INSTALLATION....................................................................................................... 45
7.4 THEORY OF OPERATION ................................................................................................................. 47
7.5 MAINTENANCE .............................................................................................................................. 50
8MODULATED OSCILLATOR............................................................................................................54
8.1 DESCRIPTION.................................................................................................................................. 54
8.2 ELECTRICAL CHARACTERISTICS. ...................................................................................................... 54
8.3 REMOVAL AND INSTALLATION....................................................................................................... 54
8.4 THEORY OF OPERATION ................................................................................................................. 55
8.5 FUNCTIONAL DESCRIPTION. ........................................................................................................... 55
8.6 MAINTENANCE .............................................................................................................................. 57
8.7 TROUBLESHOOTING....................................................................................................................... 57
9AFC/PLL……..................................................................................................................................58
9.1 DESCRIPTION.................................................................................................................................. 58
9.2 ELECTRICAL CHARACTERISTICS. ...................................................................................................... 58
9.3 REMOVAL AND INSTALLATION....................................................................................................... 59
9.4 THEORY OF OPERATION ................................................................................................................. 59
9.5 FUNCTIONAL DESCRIPTION. ........................................................................................................... 59
9.6 MAINTENANCE .............................................................................................................................. 64
9.7 ELECTRICAL ADJUSTMENTS. ........................................................................................................... 64
9.8 TROUBLESHOOTING....................................................................................................................... 70
10 RF AMPLIFIER ...............................................................................................................................74
10.1 DESCRIPTION.................................................................................................................................. 74
10.2 ELECTRICAL SPECIFICATIONS. ......................................................................................................... 74
10.3 REMOVAL AND INSTALLATION....................................................................................................... 74
10.4 THEORY OF OPERATION ................................................................................................................. 75
10.5 MAINTENANCE .............................................................................................................................. 78
10.6 TROUBLESHOOTING....................................................................................................................... 82
11 SYNCHRONOUS FM BOOSTER.......................................................................................................84
11.1 SYSTEM DESCRIPTION. ................................................................................................................... 84
11.2 SYSTEM CONFIGURATIONS. ........................................................................................................... 84
11.3 ELECTRICAL SPECIFICATIONS. ......................................................................................................... 84