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250W Professional FM Radio Transmitter
- STEREO, AUDIO PROCESSING OPTION
- MPX ONLY OPTION
- 48VDC or 90-260VAC OPTION
- USB 192 KHz 24 bit OPTION
- INCLUDES SHIPPING
- 5 YEAR WARRANTY
- EXCEEDS CE/FCC TECHNICAL SPECIFICATION
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LIMITED WARRANTY |
Suitability
This is a beautiful machine, recently upgraded to 250 watts for the 200 watt version we sold for over a decade. There are lot of these units going strong in the world working 24/7 without a hiccup. The internal 250 watt amplifier blocks will operate with ease at full power 24 hours a day non stop in any country and with any AC voltage in the world. The front panel has a neat little meter panel lit up in blue to indicate forward and reflected power.
Which Version Do You Need?
These are the two main versions of this transmitter:
◼ Stereo with RDS and Audio Processing Version
◼ MPX Version
These two versions cover 90% of all customer requirements. Other custom versions are available such as stereo only, no RDS, no processing etc. which we can also make if that's what you require.
You will find these two main versions shown in detail in the two following sections with descriptions of what they do and how they work. You should also see the price, INCLUDING delivery, to your country.
If you are still unsure, you are always welcome to contact us at em: info@aareff.com or ws: +1 829 6980733 and we're more than happy to advise you.
Do You Have A Question?
Stereo, RDS, and Audio Processing Version
If you're unsure which version to choose, this is the ideal option. It automatically adjusts audio levels, ensuring that your 250 watt transmitter remains within the legal specifications set by state regulators. This makes it a great choice for beginners.
Professionals will also appreciate this version as it eliminates the hassle of manual adjustments. Housed in a single enclosure, it includes everything needed for optimal performance. The built-in audio processing ensures a loud yet legally compliant audio level, preventing over-deviation and regulatory issues. Achieving the perfect balance between maximum loudness and compliance is crucial, and this version, with stereo functionality and internal audio processors, accomplishes just that.
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The audio inputs conform to the industry standard: 600 ohm +4 dBu balanced, using XLR connectors.
Additionally, this version INCLUDES RDS, allowing your station name and other information to scroll across car radio displays.
This is not just ordinary RDS; it features fully programmable dynamic RDS. By connecting the transmitter to a PC via USB, you can modify the RDS data in real-time using the USB PC CONTROL shown below.
Flat 30Hz to 76KHz MPX Input
This is for expert users who want to provide the MPX signal from an external source.
The baseband MPX audio input has virtually no tilt whatsoever on the low bass frequencies making it perfect for use with multiband processors such as Orban, Invonics, Stereo Tool, Omnia etc. Check the image of the test we made in MpxTool.
The PLL is loop is very slow, this is good as it maintains low frequency performance down to just a few Hertz. This low frequency response is heaven for processors.
This is achieved by a Hartley loosely coupled Push-Push voltage controlled oscillator (VCO) that is so stable it remains within 10kHz of it's tuned frequency free running when the DSS and PLL is disabled.
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This extreme level of inherent VCO stability means the PLL has a little work to do maintaining the frequency to an accuracy of less than 300Hz, the PLL is only giving it a slight touch. As consequence of this 1: low noise audio is achieved as talked about in the previous paragraph; and 2: the PLL correction voltage can be low pass filtered down to just a few Hz. With the super low frequency loop filter the low frequency audio at 30Hz is not mistaken or confused as frequency drift and passes through to the varicap completely unaffected which results in low frequency audio response which is essential for high performance audio processors
12V and 48V DC Option
The regular version of this unit is 90 to 260V AC. However we can also manufacture it for 12V or 48V DC. To the best of our knowledge, in the entire world, Only We Make 12V DC FM Broadcasting Transmitters and Amplifiers up to RF Power Outputs of 250W.
Applications include mobile setups where only a car or vehicle battery is available. We have a perfect Magnetic Mount FM Antenna for mobile setups. Also fixed installations with connection to solar battery systems of 12V and 48V DC
We default ship the AC version. If you want the 12 or 48V DC version, it's important you notify us by email when you make your order.
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USB PC/RDS CONTROL
Download our free PC app that connects 'plug and play' to the transmitter / PLL DDS exciter via USB. You can see the PLL status and change the frequency and power directly from the PC interface. If you choose to add the optional RDS card, you can also change the PI, PTY and scrolling text of the radio from the interface.
Below are the download links for Windows:
https://www.aareff.com/1wpllm/pll14.4/pll14.exe
https://www.aareff.com/1wpllm/pll14.4/pll14.zip
By clicking on these links, Windows may show you a warning that the software is from an unknown publisher. We assure you that we wrote the apps and the files are perfectly safe, virus-free and come from our registered domain www.aareff.com, which you can verify at https://lookup.icann.org/en/lookup
Normal state when the device is connected: the PLL is LOCKED with an output power of 0.85W and a PLL phase of 2.33V
This shows what happens if the device loses its lock. We simulated a failure by placing our fingers on the oscillator coils.
This shows the return to normal with the user command FREQ:106.7 typed in the input box below. A value between 87.5 and 108.0 MHz can be set.
After pressing 'Send:' the display returns UPDATED FREQ 106.7 along with other technical information. This causes the transmitter to change frequency.
This shows another command, RDS-PI:ABCD typed for devices with the RDS card.
After pressing 'Send': the display returns UPDATED RDS-PI:ABCD instantly updating the RDS PI code.
This shows two additional examples of RDS commands:
RDS-TEXT:[write your message here]
RDS-PTY:[number from 0 to 31]
Text is plain ASCII up to 60 chars and valid PTY Codes shown below.
Shown below are the current commands available for USB PC Control and also the PTY codes for program type. We will be making further developments, improvements and more useful commands to this app in the near future. Keep checking this page for details.
◼ DEVICE-ID
◼ STATUS
◼ FREQ:[87.5 to 108.0]
◼ DDS-ADJ:[-1,0 or 1]
◼ PWR:[0 to 1]
◼ RDS-PTY: [0 to 31 list of PTY codes]
◼ RDS-PI: [0000 to FFFF]
◼ RDS-TEXT:[any string up to 60 chars.]
◼ RDS-ON
◼ RDS-OFF
Antennas
250 Watts with a high performance well installed antenna is a typical set up for a local radio station for a big town or small city. In rural areas up to 45 miles range is possible.
• SINGLE DIPOLE
• 4.8dBi 2 DIPOLES
• 7.8dBi 4 DIPOLES
• 10.8dBi 8 DIPOLES
• 4.8dBi 5/8 ANTENNA
• -0.8dBi CIRC. DIPOLE
• Folded Dipole
Our 500W EIRP package includes this transmitter complete with antennas and cables ready to go. It is a full system that complies with the regulations of the European Union and most other countries in the world.
VSWR Protection
The RF output power of the amplifier automatically folds back, very fast to a safe level when there is fault condition of poor SWR and return loss of any level for any duration of time. When the fault clears the amplifier restores to full power.
Temperature Protection
This unit is designed with high reliability in mind to work in hot countries close to the equator. The cooling system incorporates at the back three 60 mm fans and at the front one 80mm fan to keep the heatsinks in this unit cool to touch by hand. Many of these units are operational for years in Nigeria without any issues. If this is not enough, if any of the fans were to fail, and let's face it and be honest, that could happen after a few years of use, the internal temperature sensor will reduce the amplifier power down to a safe level to keep the temperature in check until the fan has been replaced by a new one.
Construction
The enclosure is made in strong 16 gauge steel, powder coated and baked in satin black. This leaves a tough, durable surface that will never rot or corrode and be cleaned to shine for decades. The front panel is 19 inch across and 2U (3.5 inch) high with a depth of 12 inches, so it will fit with ease into a standard rack. It is very strong and difficult to damage even under extreme handling.
Frequency, Power and Deviation
The frequency and power level is easy to change, but not so easy that somebody with no experience can just press a button on the front, that would be too easy and dangerous. We reached a compromise with this, we placed these controls on the underside of the unit. To get to them, just slide the unit out of the rack, flip it over and the little dip switches will allow you to change the frequency and a trim pots for the power and deviation level.
Compliance
The stereo version with audio processing and limiting meets all the regulatory standards required out of the box and pre configured. In fact if you send us a copy of your permit and it's conditions, we will set it up exactly to the specification. This equipment complies with EU/CE harmonised standards and FCC technical requirements for FM broadcasting. More information HERE
RF Specification
All stated measurements were made at 220VAC at 27 Deg. Celsius ambient temperature unless stated.
| Power Output | Adj. 1-250 Watts into 50 ohms |
| Spurious Emissions | Less than -75 dB ref to carrier |
| Harmonic Emissions | Less than -70 dB ref to carrier |
| Freq Stability | +/- 1 KHz max. typ. +/-300 Hz |
| Deviation Sensitivity Stability | +/-2 % max |
| Freq Fine Adj | > +/- 1000 Hz |
| Freq Range | 87.5 to 108 MHz in 100 KHz steps |
| Out of Lock RF Muting | Less than -70 dB ref to carrier |
| Residual AM | Less than 0.5 % |
| Synchronous AM | Less than 0.5 % |
| RF Ruggedness | Any VSWR phase or length of time |
| Output Connector | N-Female |
| Operating Temp | -20 to +40 Deg C |
AF Specification
| Pre-emphasis | (50 uS/ 75 uS/ None) Selectable | |
| Audio Input Connector | Phono/ RCA type unbalanced sockets | |
| Audio Input Sensitivity | +4 dBu for +/- 75 KHz dev. | |
| Version | MPX | Stereo and Audio Processor |
| Signal To Noise Ratio | 80dB | 65dB |
| Frequency Response | 30Hz-76KHz | 30Hz-15KHz |
| Audio Distortion | Better than 0.1% / 60dB THD | Better than 0.1% / 60dB THD |
AC Specification
| Input Voltage | 90-264 V AC 135-370 V DC 47-63 Hz |
| Input Power | 500W for 250W RF OUT with RF SWR less than 1.5 |
| Working Humidity | 20-90% RH non-condensing |
| Safety Standards | UL60950-1 TUV EN60950-1 BSMI CNS14336 CCC GB4943 J60950-1 approved |
| EMC Emission | Compliance to EN55022 class B EN61000-3-2 3 FCC PART 15 / CISPR22 class B CNS13438 class B GB17625.1 |
| EMC Immunity | Compliance to EN61000-4-2 3 4 5 6 8 11 light industry level criteria A |
