TECHNICAL DESCRIPTION A.M. BROADCAST TRANSMITTER SENDER AM 3000 SS June 2001-1- Rev. B
TRANSMITTER CHARACTERISTICS 1. BASIC OFFER The basic offer includes: One AM3000SS A.M. Medium Wave Solid State Broadcast Transmitter. One Technical Manual. 2. SALES CONDITIONS 2.1 General Offered equipment corresponds to the latest state of the art technology and complies with international requirements and stipulated specifications. The equipment is fully tuned and tested at customer specified frequency, and is constructed and assembled using first quality components and materials. 2.2 Transmitter Components Single phase 220V 50/60 Hz. Power supply with main A.C. isolation transformer and input R.F. filtering. The transmitter may be ordered optionally for three phase operation. One frequency synthesizer covering the 530 KHz. to 1700 KHz Band. One PWM modulator with two selectable power levels. Four hot unpluggable power amplifiers. Control system for local or remote control of transmitter operation. Extensive front panel digital metering and signaling. Protective system including SWR, overcurrent, overvoltage, overtemperature, overpower, low drive, phase failure and other protections with sequential power reduction. June 2001-2- Rev. B
Bandpass output R.F. filter with lightning protection. Low velocity air cooling system. Compact aluminum cabinet with locked front doors and stainless steel hardware, completely rustfree. One Technical Manual with specific test data. 2.3 Customer Required Relevant Information Mains A.C. supply is 220V +/- 10%, 47 to 65 Hz, single phase. voltages or three phase operation is required contact with the factory. If other Power supply includes main circuit breaker and varistor transient protection. Output connector is 50 Ohm 7/8" E.I.A. flange. Dimensions and weight: - Width: 19.3 (49 cm) - Height: 24 (61 cm) - Depth: 26 (66 cm) - Weight: 330 lb (150 kg) including crating 2.4 Warranty Equipment shall be in warranty for a period of 24 months from the delivery date. The transmitter shall be guaranteed against all defects that should arise as a cause of defective material and or workmanship, unless such defects can be proved to be due to misuse, mishandling or installation conditions not complying with the requirements included in the transmitter Technical Manual. Under warranty conditions, SENDER will replace or repair any defective part, free of charge. June 2001-3- Rev. B
The warranty is conditioned to a correct transmitter installation specially regarding grounding, lightning protection, A.C. supply transient protection and A.C. supply voltage limits. 2.5 Spare Parts SENDER ensures the availability of spare parts and components for a period of 10 years from the delivery date. In the event that an exact spare may not be available, a suitable replacement shall be supplied. Sender undertakes to perform any necessary modification required to accept a spare part different from the original, for a period of ten years. A basic set of spare parts including fuses and semiconductors is optionally available upon request. 2.6 Delivery Confirm with the factory. Usually 7 working days from the date of contract signature and deposit, the offered equipment will be ready for acceptance test, unless other agreement. If the client decides not to participate in the factory acceptance test, official written notice must be given and the delivery will follow immediately afterwards. June 2001-4- Rev. B
3. PRODUCT DESCRIPTION SENDER AM 3000 SS broadcast transmitter is designed to operate in any channel in the frequency band between 530 KHz and 1700 KHz. The nominal R.F. carrier power is 2.5 kw with 150% modulation capacity into a 50 ohm load. When operating at carrier level of 2.75 kw modulation capacity is 125%. Maximum carrier power is 3 kw with 100 % modulation capacity. All SENDER Transmitters are fully Solid State, using a modular redundant architecture, employing class D high efficiency R.F. power amplifiers and polyphase PWM modulators. The transmitter includes a frequency synthesizer that may be easily adjusted to operate in any channel inside the A.M. band. The equipment typically uses a 220V +/- 10%, 47 to 65 Hz, single phase power supply. The transmitter is supplied with two independently adjustable power levels. Power levels may be locally or remotely selected and may be preset between 0.1 and 1.2 times the nominal power. In addition, a step type power control permits a +/- 15% fine adjustment of the preset power level. This adjustment may be commanded locally or by remote control. An external interface permits monitoring the most important operating parameters and to command main functions. 3.1 Physical Description The transmitter is contained in a double compact cabinet. construction employed uses nine different assemblies: The modular A1 Power Supply. A1A1 Regulators/ filter capacitors sub-assembly. A1A2 Capacitor discharge and 270 V addition subassembly A2 A3 Control. PWM modulator (PWM=Pulse width modulation). June 2001-5- Rev. B
A4 A5 Synthesizer. Upper Modulated Power Amplifiers. A5A1 Amplifier Nº1 A5A2 Amplifier Nº2 A6 Lower Modulated Power Amplifiers. A6A1 Amplifier Nº3 A6A2 Amplifier Nº4 A7 Back Panel. A7A1 Motherboard A7A2 R.F. Summing Transformer A8 Output Filter. A8A1 Directional wattmeter sub-assembly. A8A2 Transient suppressor sub-assembly. A9 Blowers. Audio and remote control connections are located in a terminal board in the transmitter back. The mains connection is included in a terminal board located at the transmitter base plate. The 7/8" E.I.A. R.F. output is located on the rear panel of the transmitter, close to the upper-right corner. A BNC connector located at the back of the transmitter provides a sample suitable to operate an external modulation monitor. The fresh air inputs through the lower part of the cabinet back and exhausts through the top. June 2001-6- Rev. B
3.2 Functional Description Transmitter functional blocks are: 1) A1 Power Supply. Located in the lower compartment of the transmitter, with the following functions: A.C. mains connections and transformer tap selection. Ferrite toroids in the A.C., audio and external interface conductors, to limit the effects of an eventual strike in the A.C. distribution lines or in telephone lines. Circuit breaker with overload and short circuit protection of the A.C. feed. Rectification and filtering of the main D.C. voltage. Rectification, filtering and regulation of the auxiliary D.C. voltages. Inrush current limiting. Discharge of the filtering capacitors. Current and voltage samples generation, to be used by the control system. Varistor transient protection. 2) A2 Control. The control card includes the following signaling and command elements: DENOMINATION FUNCTION INDICATION A2S1 (OFF) Off LED (Green) A2S2 (ON) On LED (Red) A2S3 (Reset) Alarm reset -- A2S4 ( ) Upper and lower amplifier measurement selection.(bmod, IPB, tºr.f., tºpwm). A2S5 ( ) Advance multimeter reading. -- A2S6 ( ) Reverse multimeter reading. -- 2 LED (Yellow) June 2001-7- Rev. B
DENOMINATION FUNCTION INDICATION A2S7 ( -- ) Selects power meter reading. -- A2S8 ( P1 ) Selects power level 1. LED (Yellow) A2S9 ( P2 ) Selects power level 2. LED (Yellow) A2S10 ( ) Output power increase. A2S11 ( ) Output power reduction. A2S12 (LcRm) Selects between local and remote operation. 2 LED (Yellow) The control board includes two digital meters. Following parameters can be measured: +B voltage in each P.A. Modulator current in each P.A. R.F. amplifier temperature in each P.A. PWM amplifier temperature in each P.A. Main supply D.C. voltage. Main supply total current. R.F. drive peak voltage. R.F. drive RMS current. Synthesizer PLL control voltage. +9V auxiliary supply voltage. -15V auxiliary supply voltage. Incident power. Reverse power. The control board contains the necessary circuits to display the operational parameters scaled accordingly. June 2001-8- Rev. B
Protective circuits and connectors used to distribute signals and D.C. voltages to other boards are also included. A connector is provided to install a battery to freeze the alarm status in the event of a power failure. 3) A3 PWM Modulator. The PWM modulator uses an instrumentation type audio amplifier with balanced input. Two PWM pilot signals with a relative phase displacement of 180º are generated from a crystal controlled frequency reference. This dual phase technique improves the output spectrum, reducing the components associated with the fundamental of the pilot frequency. The modulator includes electronic circuits with the following functions: Soft start. Automatic power control. Discrete and quasi-continuous power adjustment. Balanced to unbalanced audio conversion. Adjustable positive and negative peak limiter. Hum and noise compensation. Fast protection through PWM signal disable. 4) A4 Synthesizer. The synthesizer generates a high stability R.F. drive signal at carrier frequency. Frequency is defined by the position of a set of dip switches. A BNC socket accepts an external reference signal for C-QUAM. stereo operation. June 2001-9- Rev. B
5) A5-A6 Modulated Power Amplifiers. The modulated power amplifier includes 4 identical modulated amplifiers that are easily plugged or unplugged into a motherboard. Each modulated power amplifier is included in a single PCB. The R.F. power amplifier is of the bridge type and operates in class D. The PWM power stage includes two hexfets, of the same type used for R.F. amplification, each one associated with its own filter and damper diode. The amplifiers can be hot plugged or unplugged, in a motherboard that includes contacts for the main D.C. voltage, R.F. drive and R.F. output. A DB-25 socket in the front of each amplifier accepts the PWM pilot signals, auxiliary D.C. voltages and command, signaling and measurements signals. Each amplifier is internally protected against low drive voltage, overtemperature, drive unbalance and output short circuit. For safety reasons, a spring loaded switch discharges the amplifier filter capacitors when the PCB is unplugged. 6) A7 Back Assembly. The central section of the transmitter back includes a box containing the sockets where the power amplifiers are inserted, and the R.F. drive amplifier and tuning circuits. A7A1 Motherboard. Includes the 31 pin sockets that receive the power amplifier plugs. Mentioned jacks feed the drive signal, RF output signal, D.C supply and the insertion loop. To avoid the generation of dangerous voltages when one amplifier is removed, a switch that operate when its associated power amplifier is removed, shorts the primary winding of the output transformer corresponding to the removed amplifier. Mentioned switches are actuated trough the guide pins of the power amplifiers. A7A2 R.F. Summing Transformer. The output transformers for the power amplifiers are located close to the back plane PCB. Mentioned transformers have an isolated secondary winding that is series connected to add the power of the 4 amplifiers. June 2001-10- Rev. B
8) A8 Output Filter. Following functions are assigned to the output filter: To adapt the load impedance to the value required by the amplifiers. To attenuate the harmonics present at the amplifier's output. To protect against antenna over-voltages and transients. The output filter is assembled using frequency dependent coils and capacitors and is located at the transmitter top section. A8A1 Directional Wattmeter. The directional wattmeter generates voltages proportional to the square root of the incident and reverse power. Mentioned voltages are processed in the control board, used to protect the transmitter against excessive VSWR conditions and to display the direct and reverse power. Additionally, the wattmeter board includes a BNC socket with an R.F. sample adequate for the operation of a modulation monitor. A8A2 is a subassembly includes a solid state transient protector. 9) A9 Blowers. The power amplifiers are cooled forcing air through the extruded heatsinks. Two sets of blowers are located in the transmitter central compartment, one set below and one above the power amplifiers. June 2001-11- Rev. B
4. SPECIFICATIONS 1. Frequency range: 530 khz to 1700 khz. 2. Output power : 2.5 kw with 150% modulation capacity. 2.75 kw with 125% modulation capacity. 3 kw with 100% modulation capacity. 3. Maximum power to operate with 100% modulation, continuous tone: 2.75 KW. 4. Power reduction: Two levels standard, up to four upon request, +/- 15% fine adjustment. 5. Configuration: Modular redundant, with 4 hot unpluggable and interchangeable power amplifiers. 6. A.C. power source: 220V +/- 10%, 47 Hz to 65 Hz, single phase. Other voltages or frequencies upon request. 7. R.F. Output impedance: 50 ohms unbalanced. 8. Max S.W.R.: 1.5:1 9. Output connector: Type 7/8" E.I.A. Flange. 10. Harmonic and spurious radiation: Lower than -77 db referred to carrier, at nominal power. 11. Frequency stability: Better than 5 parts per million from 32ºF to 122ºF (0ºC to 50ºC). 12. Audio response: Better than +/- 1 db between 30 Hz and 10 khz. 13. A.F. distortion: Less than 1% @ 90% modulation, 30Hz to 10 khz., at nominal power. 14. Noise and hum : Less than -65 db measured in a 20 Hz to 22 khz band. June 2001-12- Rev. B
15. Carrier shift: Less than 1% between 0% and 95% modulation at 400 Hz. 16. Audio input level: +10 dbm nominal. Internally adjustable between 0 dbm and +13 dbm. 17. Efficiency: > 80% 18. Temperature range: Storage: 5ºF to 167ºF (-15ºC to +75ºC). Operation: 14ºF to 122ºF (-10ºC to +50ºC). 20. Altitude: 0 to 10000 ft (3000 meters) above sea level. For higher altitudes consult with the factory. 21. Humidity: 0 to 95% non condensing. 22. Size and weight: Width: 19.3 (49 cm) Height: 24 (61 cm) Depth: 26 (66 cm) Gross weight: 330 lb (150 kg) NOTE: Specifications may change without notice. June 2001-13- Rev. B