Broadcast MT100-E User manual

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OWNERS MANUAL
Model MT100 (-E & -U)
100 WATT FM STEREO TRANSMITTER

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USER NOTICES
IT IS VERY IMPORTANT TO READ THE FOLLOWING MANUAL SECTIONS PRIOR
TO OPERATION OF THIS TRANSMITTER!
Notice 1
The transmitter main operating voltage setting is marked on the rear of the MT100
chassis. It may be necessary to change this setting for your operating condition.
Please refer to AC Main Voltage Setting in section 6.0 Set Up Procedure.
Notice 2
The transmitter operating frequency from the factory may not be set for your authorized
frequency as it is normally set for a mid band value such as 98.0 MHz.
Please refer to Frequency Of Operation Change in section 6.0 Set Up Procedure.
Notice 3
For adjusting the RF output power setting a qualified technician should employ the use of
an RF Wattmeter and a calibrated dummy load.
Please refer to the section entitled RF Power Control in section 3.4 of this
manual.
Notice 4
The factory settings of this manual for such this as Input Selection, preemphasis, and
input sensitivity may not be correct for your application or installation requirements.
Please refer to the other exciter settings in section 6.0 Set Up Procedure where
you will be directed where else to reference in this manual.
GENERAL COMMENTS
THIS PRODUCT DOES NOT INCLUDE A DETAILED TECHNICAL MANUAL, RATHER AN
ENHANCED OPERATORS MANUAL. WHAT THIS DOCUMENTATION IS INTENDED TO DO
IS TO GIVE THE USER THE CORRECT INSTRUCTIONS AND INDICATIONS ABOUT HOW
TO OPERATE AND PERFORM PERIODIC CHECKS AND DETERMINE IF THE TRANSMITTER
IS FUNCTIONING PROPERLY.
WE ARE AWARE THAT THE TRANSMITTER DOCUMENTATION MAY PRESENT SOME
SMALL AMBIGUITIES AND IMPERFECTIONS, MANY OF WHICH HAVE ALREADY BEEN
NOTED AND RESOLVED IN THE NEXT RELEASE AND PRODUCTION. FOR THIS REASON,
EVERY OBSERVATIONS/SUGGESTIONS OR PARTICULAR COMMENTS ARE WELCOME.

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ELECTRONIC FILES OF THE SCHEMATIC DIAGRAMS IN THIS MANUAL ARE AVAILABLE.
SHOULD A LARGER MORE VIEWABLE VERSION OF ANY DIAGRAM BE REQUIRED NOTIFY
RICHARDSON ELECTRONICS, LTD.
TO CALL OUR TECHNICAL SUPPORT CENTER OR FOR OTHER CUSTOMER SERVICE
ISSUES AT RICHARDSON ELECTRONICS IN LA FOX, ILLINOIS REFER TO THE FOLLOWING
NUMBERS:
TECHNICAL SUPPORT: 630-208-2790
CUSTOMER SERVICE: 630-208-2304

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Returns and Exchanges
Equipment (Damaged or undamaged) should not be returned unless written approval and
a Merchandise Return Authorization (MRA Number) is received from your Richardson Sales
representative or Richardson Customer Service. Special shipping instruction will be
provided which will assure proper handling. The circumstances and reasons for the return
must be included in the request for return. Equipment that is special or “custom” ordered
may be not returnable. In situations where return or exchange is at the request of the
customer a restocking fee may be charged. All returns must be sent freight prepaid and
properly insured by customer. When communicating with Broadcast Richardson please
refer to your Order or Invoice Number.
Unpacking
Use care when unpacking the equipment. First perform a visual inspection of the item(s)
to determine if any damage occurred during shipment. Be sure to retain all the shipping
materials (crates and boxes or cartons) until such time that it has been determined that
the received equipment arrived undamaged. Find all PACKING LISTS and keep them to
assist in locating and identifying any components or assemblies that may have been
removed for shipping and might need to be reinstalled in the equipment. Make sure that
all shipping straps, supports and packing materials are completely removed from the
equipment prior to initialization and use.
Technical Support
Should you need technical assistance or trouble shooting guidance contact Broadcast
Richardson in your local area or you can reach assistance from Broadcast Richardson
in La Fox, Illinois at telephone [phone], Fax [phone] or Customer
Service at [phone].
Throughout the world there are many Richardson Electronics, Ltd. offices that are also
able to assist in contacting our technical support team.

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WARNING!
THE VOLTAGES AND CURRENTS IN THIS EQUIPMENT ARE DANGEROUS. PERSONEL
MUST, AT ALL TIMES, OBSERVE SAFETY WARNINGS, INSTRUCTIONS, AND ANY
REGULATIONS.
This owner’s manual is intended as a general guide for trained and qualified
personnel who are aware of the dangers that are inherent in the handling and
operation of potentially hazardous electrical and electronic circuits. It is not
the intent of this manual to provide a complete set of safety instructions or
precautions that should already be understood by trained or experienced
personnel in using this or other types of electronic equipment.
The installation, operation, and maintenance of this equipment involves risks to
personnel and also to the equipment. Broadcast Richardson or Richardson
Electronics, Ltd. shall not be responsible for injury or damage that is the result
of improper procedures or use by persons improperly trained or lacking the
knowledge to perform associated tasks.
All local codes for building, safety, fire, or related standards must be observed.
Consult local authorities for the standards for the area or region where the
equipment will be installed and put in use.
WARNING!
AT ALL TIMES DISCONECT AC/MAINS POWER BEFORE OPENING COVERS, DOORS,
ENCLOSURES, PANELS, OR PROTECTIVE SHIELDS THAT EXPOSE LIVE CIRCUITS. USE
ANY GROUNDING STICKS OR OTHER SHORTING PROBES TO DRAIN ENERGY FROM
CIRCUITS BEFORE SERVICING. NEVER PERFORM MAINTENANCE, MAKE ADJUSTMENTS,
OR SERVICE THE EQUIPMENT WHEN ALONE OR FATIGUED.
WARNING!
IF ELECTROLYTIC OR OIL FILLED CAPACITORS ARE UTILIZED IN THE EQUIPMENT AND
THE COMPONENT APPEARS LEAKY, OR IS BULGING, OR IF THE CASE OR COVERING OF
THE COMPONENT APPEARS DAMAGED OR DISTRESSED ALLOW SUFFICIENT TIME FOR
THE UNIT TO COOL OR FULLY DISCHARGE BEFORE SERVICING. SERVICING HOT OR
LEAKY CAPACITORS CAN CAUSE A RUPTURE OF THE CASE AND POSSIBLE INJURY.
Should accident or injury occur personnel engaged in the installation,
operation, or service of the equipment should seek proper medical attention. It
is advisable that such personnel have familiarity with first-aid practices.

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Table of Contents
User Notices page 2
Returns & Exchanges page 4
Unpacking page 4
Technical Support page 4
Warning page 5
Table of Contents page 6
MT100 Datasheet with Picture
1.0 Overview page 8
2.0 MT100 Basic Block Diagram page 8
3.0 Subassemblies Description Page 8
3.1 MT100 AC/DC Power Supply page 8
3.2 MT100 DC/DC Power Supply page 9
3.3 FM Stereo Exciter page 9
3.4 MT100 RF Control Circuit page 9
3.5 MT100 RF Amplifier page 10
3.6 Low Pass Filter and Directional Coupler page 11
4.0 MT100 Technical Specifications page 12
5.0 Set up Procedure page 14
OME-1T Exciter Section
6.0 General / Front Panel Graphic Page 1 of 4
7.0 Physical Page 2 of 4
8.0 Monaural Operation Page 2 of 4
9.0 Wideband Stereo Operation Page 2 of 4
10.0 Built In Stereo Encoder Operation Page 3 of 4
11.0 SCA/RDS & AUX Inputs Page 3 of 4
12.0 OME-1T Component Layout Page 4 of 4
13.0 Jumper and Switch Setting guide Page 4 of 4

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Schematic Diagrams and Components Locations
14.0 OME-1T Schematic Diagram
15.0 MT100 Amplifier Schematic
16.0 MT100 RF Board Layout
17.0 MT100 Logic Control Board Layout
18.0 Logic Control Board MT100 Schematic
19.0 MT100 Low Pass Filter Layout
20.0 MT100 GR00175 – 250W Low Pass Filter Schematic
21.0 100W Directional Coupler Layout
22.0 100W Directional Coupler Schematic
23.0 DC/DC Converter Layout
24.0 DC/DC 90W Converter Schmatic
25.0 Lase AC/DC 300W Switching Power Supply

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MT100 STEREO LOW POWER FM TRANSMITTER
100 WATT
1.0 OVERVIEW
MT100 is a 100 Watt FM Low Power Transmitter. It is very simple and easy to use. It is
composed of a mechanical frame (19 inches std., 3 RU high and 500mm depth), an exciter
(OME-1T), a RF section, which comprises a RF control board and an amplifier section, a
directional coupler and a low pass filter, a display, a power supply with a AC/DC converter
and a DC/DC converter.
2.0 MT100 BASIC BLOCK DIAGRAM
FANS
FUSE
28 Vdc
-V
+V
LED
(DISPLAY)
ENABLE
110 or 220Vac
L.P.F.
Delay line
RF out
LOW PASS FILTER and
DIRECTIONAL COUPLER
RF AMPLIFIER SECTION
REFL1 REFL2 FWD
RF
PROTECTION
TEMPERATURE
RF CONTROL
CIRCUIT
RF
Monitor
AC/DC CONVERTER
DC/DC CONVERTER
28Vin
28Vdc
15Vdc
FANs
EXTERNAL
ENABLE
OME-1T
FM Exciter
RFout 1Wmax
Left
Rigth
Ext/MPX
SCA/RDS
AUX
+15Vdc
FINAL
STAGE
DRIVER
STAGE
Not
Used
3.0 SUBASSEMBLIES DESCRIPTION
3.1 MT100 AC/DC Power Supply
The AC/DC power supply is a vendor-supplied product. The input voltage is manually
selectable for 220V or 110V, while the regulation range of the output voltage is 28V. The
input voltage selector switch is located on the front of the power supply inside the MT100
chassis. The VADJ control is used to stabilize the output power. Below, are the power
supply technical specifications:

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Input 110 Vac or 220 +/- 15% (manually switched)
Output 28 to 30 Vdc
Imax 10Aoperating;15Ashortcircuit
Efficiency 85% typ.
Isolation 4 KV (In/out or In/GND)
Weight(Typ.) 1500g
Size (WxHxD) 120x80x200
3.2 MT100 DC/DC Power Supply
The MT100 uses a DC/DC converter. It provides a voltage of 15V to the exciter and power
to the fan circuits. Below, the technical specifications:
Vdc Input 20 up to 53 Vdc
Output 1 15 Vdc/1.5 A
Output 2 28 Vdc/3 A
3.3 FM Stereo Exciter
The exciter is RFCast model OME-1T. The declared nominal RF output power is 1 Watt;
this signal arrives to the RF final stage through the RF protection circuit. All the input
connections are arranged on the front panel. Please refer to the annex datasheet at the
back of this manual for more detailed specifications and for operational settings.
3.4 MT100 RF Control Circuit
The RF input circuit has 3 main functions:
1) RF power control
2) RF protection
3) Measurement/status indication
RF Power Control. A pin diode attenuator controls the RF input power coming from the
exciter (OME-1T). RT3 trimmer may manually control this attenuator located on the
internal control panel, in order to adjust for the output power requirement. The AGC
control regulates the power, manually set, versus frequency and/or temperature changes.
Moreover, the input attenuator includes a soft start, activated at the switching on or after
any RF protection intervention. To access RT3 the operator engineer will need to remove
the transmitter top cover.
When the MT100 works at a very high temperature and/or high reflected output power, a
derating circuit is provided to decrease the output power in order to allow the equipment
on function at a reduced power.

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RF Protection. A fast comparator switches when the output detected reflected power
exceeds a pre-set threshold. The regulation of this threshold is made by RT2 trimmer,
adjusted in factory for a value of 20 Watts. When the protection is switched on, the
protection circuitry removes the RF signal applied to the final stage amplifier very quickly,
in about 1 microsecond.
Measurement/status indication. The two main measurements, FWD and REF power,
are displayed by two BAR LEDs. The MT100 status is indicated with 3 LED's: RF nominal,
RF fault, RF derating. The RF fault is on when the output power is lower than 3 dB related
to the nominal output power. If the power decreases in derating conditions, the fault is off
in all cases. The “enable” switch (SW1) is located on the front panel. It is possible to
operate the enable switch by using the contacts on the rear chassis panel of MT100. The
enable mode of the amplifier is realized when switch SW1 is on and the rear panel
contacts (jumper) are closed.
WARNING: with enable off, there is no RF out but all the internal circuits are powered
(stand by condition). Remember to switch off the main on / off switch on the transmitter
rear panel and remove the power cord before opening the top cover or operating any
inside circuits. Operating with the transmitter cover removed also affects the proper
cooling of the RF amplifier.
3.5 MT100 RF Amplifier
The RF amplifier section provides to amplify the RF signal coming from the RF control
circuit.
It is composed by:
•2 way 90 deg. hybrid splitter
•driver stage
•final stage
•2 way 90 deg. hybrid combiner
The 2way splitter is made by a 90 deg. Hybrid structure and provides to split in
quadrature the input signal. Below, the technical specifications:
Frequency 87.5 – 108 MHz
Input power 50W Max
Return Loss (S11) <-17 dB
Return Loss (S22 ed S33) <-15 dB
Isolation (S32) >15 dB
Insertion Loss (S21=S31) <0.6 dB
The driver stage provides the first step of amplification of minimum 14dB gain in order
to correctly drive the final stages. It is composed by a pair of SINGLE END stages
operating in class AB. Below are the technical specifications:
VCC 28V
Idq 50mApersection