Richardson Electronics MT300 300W FM Transmitter User Manual 430026
Richardson Electronics Ltd 300W FM Transmitter 430026
Exhibit D Users Manual per 2 1033 c3
RFCAST – MT300. Rev. 2: 05-17-04
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OWNERS MANUAL
Model MT300 (-E & -U)
300 WATT FM STEREO TRANSMITTER
RFCAST – MT300. Rev. 2: 05-17-04
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Table of Contents
Table of Contents page 2
User Notices page 4
Warning page 5
Returns & Exchanges page 6
Unpacking page 6
Technical Support page 6
1.0 Overview page 7
2.0 MT300 Basic Block Diagram page 7
3.0 Subassemblies Description Page 7
3.1 MT300 AC/DC Power Supply page 7
3.2 MT300 DC/DC Power Supply page 8
3.3 FM Stereo Exciter page 8
3.4 MT300 RF Control Circuit page 8
3.5 MT300 RF Amplifier page 9
3.6 Low Pass Filter and Directional Coupler page 10
4.0 MT300 Technical Specifications page 10
5.0 Set up Procedure page 12
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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
Schematic Diagrams and Components Locations
14.0 OME-1T Schematic Diagram
15.0 300W RF Module
16.0 Layout FM300-108SD
17.0 MOSFET FM 300W RF Amplifier Schematic
18.0 Layout MDL30
19.0 MDL30 Schematic
20.0 MT300 / MT250 Logic Control Board Layout
21.0 Logic Control Board MT250 / MT300 Schematic
22.0 300W Low Pass Filter Layout – MT100/250/300 Low Pass Filter
23.0 300W Low Pass Filter Schematic
24.0 300W Directional Coupler Layout
25.0 300W Directional Coupler Schematic
26.0 DC/DC Converter Layout
27.0 DC/DC 90W Converter Schmatic
28.0 JWS300 – 600 Series Instruction Manual
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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 MT300 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.
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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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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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 +1 (630) 208-2782, Fax +1 (630) 208-2551 or Customer Service at +1 630-208-2304.
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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MT300 FM LOW POWER TRANSMITTER
300 WATT
1.0 OVERVIEW
MT300 is a 300 Watt FM Stereo Low Power Transmitter. It is very simple and easy to operate. It is
composed of a mechanical frame (19 inches std., 3 RU high and 500mm depth), a stereo exciter
(OME-1T), a RF section, comprised of a RF control board and an amplifier section, a directional
coupler and low pass filter, a display, and power supply composed of a AC/DC converter and a
DC/DC converter.
2.0 BASIC BLOCK DIAGRAM OF MT300
FANS
FUSE
48 Vdc
-V
+V
LED
(DISPLAY)
ENABLE
110/220V
L.P.F.
Delay line
RF out
LOW PASS FILTER and
DIRECTIONAL COUPLER
RF AMPLIFIER SECTION
REFL1 REFL2 FWD
RF
PROTECTION
DRIVER
(MDL30)
FINAL STAGE
(FM300-108)
TEMPERATURE
RF CONTROL
CIRCUIT
RF
Monitor
AC/DC CONVERTER
DC/DC CONVERTER
48 Vin
28 Vdc
15 Vdc
FANs
EXTERNAL
ENABLE
OME-1T
FM Exciter
RFout 1Wmax
Left
Rigth
Ext/MPX
SCA/RDS
AUX 15Vdc
3.0 SUBASSEMBLIES DESCRIPTION
3.1 MT300 AC/DC Power Supply
This power supply is a vendor-supplied product. The supply is an AC/DC supply that has a wide
operating range permitting input voltages of 85 to 265 V producing an output voltage of 48V.
Below are the technical specifications:
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Nominal Output Voltage 48V
Max Output Current 13A
Max Output Power 624 Watt
Efficiency 83% typ.
Input Voltage Range 85-265VAC (47-63Hz)
PFHC Built to meet EN61000-3-2
Power Factor(100/200VAC) (typ) 0.99/0.95
Output Voltage Range 43.2-52.8V
Over Voltage Protection 55.2-64.8
3.2 MT300 DC/DC Power Supply
The MT300 uses a DC/DC converter to provide a voltage of 15V to the exciter and a pulsed voltage
of 28V to the fans (pulsing does not reduce the fans effectiveness but provides for hard start
conditions). In addition, it supplies a voltage of 28V to the driver (MDL30). Below, are 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 is delivered to the RF final stage through the RF protection circuit. All the input connections
are arranged on the front panel. (See the annex datasheet at a later section in this manual). Located
on the rear panel of the MT300 are also Left & right audio inputs that appear on a screw terminal
strip for convenience when rack mounted.
3.4 MT300 RF Control Circuit
The RF input circuit has 3 main functions:
RF power control
RF protection
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Measurement/status indication
RF Power Control. A pin diode attenuator controls the RF input power coming from the exciter
(OME-1T). This attenuator can be manually controlled by trimmer RT3 located on the internal
control panel, to permit adjustment for the desired output power. To access RT3 the operator
engineer will need to remove the transmitter top cover and locate the trimmer on the control panel
using the Logic Control Board Layout Drawing found later in this manual. An AGC control
regulates the output power, manually set, versus frequency and/or temperature changes. Moreover,
the input attenuator includes a soft start, activated when switching on or after any RF protection
intervention.
When the MT300 operates at a very high temperature and/or high reflected output power, a derating
circuit is provided to decrease the output power to maintain equipment operation, although at a
lower power.
RF Protection. A fast comparator switches when the detected output reflected power exceeds a
pre-set threshold. The regulation of this threshold is made by RT2 trimmer, factory adjusted to a
value of 30 Watts reflected power. When the protection is activated, the protection circuitry
removes the RF drive signal applied to the final stage amplifier very quickly, in about 1 micro
second.
Measurement/status indication. The two main measurements, FWD and REF power, are
displayed by two BAR LEDs. The MT300 status is indicated with 3 LEDs: RF nominal, RF fault,
RF derating. The RF fault is turned 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 on the front panel. It is possible to turn on (enable) the transmitter using the
contacts on the screw terminal on the transmitter rear panel. Enable or turning on the RF amplifier
is realized when switch SW1 is in the on position and the rear panel enable is closed using a jumper
connection or external relay.
WARNING: with enable off, there is no RF output, however all internal circuits are powered (stand
by condition). For safety, it is important to switch off the mains voltage source or unplug the
transmitter before operating inside. Be sure to return the transmitter cover before operating to
permit the proper airflow and cooling of components.
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3.5 MT300 RF Amplifier
The RF amplifier section serves to amplify the RF signal coming from the RF control circuit and
exciter.
It is composed of:
MDL30 (Driver)
FM300-108 (Final Stage)
The MDL30 provides the first step of amplification of minimum 17dB gain in order to correctly
drive the final stages. It is composed of a stage operating in class AB. Below, the technical
specifications:
VCC 28V
Idq 200 mA typ.
Frequency range FM ( 87.5-108 MHz )
Power Gain > 17 dB typ.
Output Power > 25 W
The final stage is an RF amplifier for FM signals operating in band II (87.5 – 108 MHz), with
nominal output power of 300 Watt CW.
Normally it works up to 330 Watt, in order to overcome the Insertion loss of the circuitry that
follows the amplifiers, being the Directional couplers and Low Pass Filter.
FM300-108 uses MOSFET technology where the RF MOSFET‘s bias is integrated on its printed
circuit board. The polarization is in class B, with a 180 mA quiescent current.
VCC nominal 48V
IDC (@ Full Power) 11 A typ.
Idq 180 mA typ.
Frequency range FM ( 87.5-108 MHz )
Power Gain Typ. 18 dB
Output Power 300 W min
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3.6 Low Pass Filter and Directional Coupler Unit
The filter has a particular elliptic configuration; this configuration has been specifically chosen to
guarantee the values of the harmonic components levels.
In-band Insertion Loss <0.5 dB
Insertion Loss @ 175MHz >55 dB
In-band Return Loss <-20 dB
The directional coupler is a block composed by 2 directional couplers and a quarter wave delay line.
Both ports of each directional coupler are used. Two of them detect the reflected power, one detects
the FWD power and one is used as RF monitor. The function of the delay line is to have two
reflected power signals detected at 90° of electrical angle. In this way, it is possible to have a quite
constant reflected power level vs. the phase angle of that signal. The RF monitor is connected to the
front panel (RF monitor port) to have 0 dBm nominal signal.
4.0 MT300 Technical Specifications
Environmental
Storage Temperature: -20/+65 °C
Operating Temperature: -5/+45 °C
Guarantee Performance Temperature: 0/+45 °C
Relative Humidity (Non Condensing): < 90%
Guarantee Performance Altitude: 2000 m, (6560 ft)
Cooling: > 150 cubic meters/hour
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RF Characteristics
Frequency Range: 87.5 – 108 MHz, 50Khz step, synthesized.
Output Power: 300 Watts nominal, (VSWR < 1.8:1).
RF Power Devices Technology: MOSFET
Off lock Attenuation: > 60 dBc
RF Output connector: N Female
RF Output Impedance: 50 Ω
RF Output monitor level: 0 dBm nominal (BNC connector on the front
panel)
RF Spurious: < -95dBc @ +/-1MHz (Exceed
.EBU/CCIR/FCC)
Harmonic: < -70dBc
Frequency stability: < 500 Hz / 6 months @ Center Frequency
Inputs: Mono, Stereo, MPX, AUX, SCA/RDS
Input Impedance: 600Ω or 5KΩ unbalanced
Modulation Type: F3E/F8E Direct FM at the carrier frequency
Frequency deviation: +/-75KHz=100%
Variation of sensitivity for 75 KHz Deviation: +/-1dB from 87.5 to 108 MHz
AF Limiter: +1dB
Center Frequency Shift: < +/-500Hz, (Due to +/-75KHz Mod)
Stereo Operation: CCIR 450/S2 “Pilot Tone System”
Asynchronous AM SNR:
(REF=100% AM Mod, @400Hz, BW=30Hz to
20KHz, FM Mod OFF)
- 56dB
Synchronous AM SNR:
(REF=100% AM Mod, @400Hz, BW=30Hz to
20KHz, FM Mod +/-75KHz @400Hz)
-50dB
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Electrical
Power Supply: 96/130 or 200/268 V, Single Phase AC, 48 to
62Hz.
Power Consumption: < 620 VA
Power Factor: > 0.9
R & Mono Input
Input connectors: BNC female (front panel)
Input Impedance: 1 Mohm resistive, unbalanced, source
impedance <10kOhm
Input level (For +/-75KHz deviation): 3 to 9 dBm/600Ω
Frequency response (30Hz to 15KHz): +/- 0.15dB
Pre-emphasis: Flat/50µSec/75µSec +/-3%
THD (30Hz to 15KHZ): 0.1%
FM S/N Ratio (REF=+/-75KHz):
Weighted CCIR 468-2; BW= 30Hz to 20KHz
flat -68dBc
with de-emphasis 50µsec -73dBc
with de-emphasis 75µsec -76dBc
No-weighted; BW= 30Hz to 20KHz
flat -73dBc
with de-emphasis 50µsec -76dBc
with de-emphasis 75µsec - 78dBc
Audio Filter rejection: (19KHz to 100KHz) >30 dB
19KHz suppression: > 46dB
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External MPX Input
Input connectors: BNC female (front panel)
Input Impedance: 10KΩ
Input level (For +/-75KHz deviation): 3 to 9 dBm/600Ω
Composite amplitude response (30Hz to
100KHz):
+/- 0.5dB
Composite phase response ( 30Hz to 53KHz): +/- 0.5°
SNR: (30Hz to 200KHz; with de-emphasis
50µsec)
> 75dB
Stereo Operation (L & R Channels)
Input connectors: BNC female (front panel)
Input Impedance: 1 Mohm resistive, unbalanced, source
impedance <10kOhm
Input level: 3 to 9 dBm/600Ω
Audio Filter Attenuation: > 68 dB @ 19 KHz
Crosstalk Attenuation (From 30 Hz to 15 KHz): > 50 dB
Pre-emphasis: Flat/50µSec/75µSec +/-3%
38 KHz Suppression: > 50 dB
Sub-Carrier Frequency: 38 KHz +/- 2Hz
Pilot Frequency: 19 KHz +/- 1Hz
Phase Difference 19/38 KHz: 0° +/- 2°
THD on Encoded Channels (30Hz to 15KHz): < 0.1%
Audio Response (30Hz to 15KHz): +/- 0.25dB
Nominal Pilot Deviation: +/- 7KHz
Pilot Output level: 1 Vpp, square wave
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SCA/RDS & AUX input
Input connectors: BNC type female (front panel)
Input Impedance: 5KΩ
Input level (for +/-7.5KHz deviation
@97.5MHz):
2.2Vpp/5KΩ
Amplitude Response (10KHz to 100KHz): +/- 0.15dB
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5.0 Set up procedure
The MT300 is shipped in a wooden box. It should be removed carefully removing the foam packing
material and the clear protective film. This equipment can be operated freestanding or by its
standard mechanical frame (19 inches), it may be mounted in an equipment rack.
AC Main Voltage Setting
The MT300 is supplied for 220Vac, +/- 15%, single phase at 50Hz or 60Hz operation but it can
operate at 110VAC single phase, because its AC/DC power supply capable of a wide operating
range. The normal current draw is approximately 2.8 amps for 220Vac operation, but, if supplied at
110Vac, the normal current is around 5.3 amps. It is installer’s responsibility to correctly connect
the three wires (line, N, GND) to the mains line use the power cord supplied. It is also
recommended that a transient or surge protector be properly grounded and the MT100 connected
through the protector. Before switching the transmitter on, it is necessary to connect the RF output
power type “N” (female) connector to either a dummy load or an FM antenna with low loss coaxial
transmission line.
Frequency of Operation Change
The MT300 transmitter operating frequency at time of shipment from the factory may not be set for
your authorized frequency. In order to change the frequency of operation, locate, the OME-1T
exciter section of this manual and review the information on page 4 of 4. After review the
frequency setting examples in this section, substitute your values for the switch settings through the
OME-1T chassis top. You should make sure that the transmitter is unplugged and that no power
present.
To access the frequency change selector switches may be necessary to remove the four (4) screws
on the front of the OME-1T and slide it forward far enough to allow a small screwdriver blade to
adjust the three (3) rotary frequency selector switches.
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Output Power Setting
Please refer to the earlier section entitled RF Power Control in section 3.4 of this manual.
Other Exciter Settings
Please refer to the OME-1T exciter section of this manual, page 4 of 4, for jumper settings for left
and right channel preemphasis selection (75 microseconds un-preemphasized, or 50 microseconds),
left and right input sensitivity selection (6..9dBm, 3..6dBm or 0..3dBm), modulation limiter
selection (On or Off), and input selection (Mono, Multiplex Internal, or Multiplex External). This
page of the manual shows the various positions for the jumpers and their location on the OME-1T
printed circuit board.
Turning On the transmitter
After the above procedures are followed, it is possible to turn the transmitter on. On the front panel,
the mains power LED indicates the status of the MT300. If it is on, the equipment has been
correctly supplied the AC line voltage. By activating the enable switch, on the front panel, the
transmitter reaches the maximum RF power set. Other LEDs provide further information on the
functioning of the MT300:
RF nominal (green): ON if some RF output power appears
Derating (yellow): ON in two situations
when the reflected power is higher than 10dB (the transmitter power output is maintained until
VSWR 2:1. If the VSWR is higher, the derating protection intervenes which stabilizes the output
power at a non-dangerous value of operation for the amplifier)
when the working temperature is too high (the temperature protection intervenes when the ambient
room temperature is ≥45°. In this case, the output power is reduced of about 6dB)
Fault (red): ON if the transmitter has other faults (for example, input power without output power,
with for example a fault in the RF amplifier or RF control circuit).