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20W Professional FM Radio Transmitter
- SUPER SILENT
- STEREO WITH AUDIO PROCESSING OPTION
- RDS OPTION
- 12VDC or 90-260VAC OPTION
- USB 192 KHz 24 bit OPTION
- INCLUDES SHIPPING
- 5 YEAR WARRANTY
- EXCEEDS CE/FCC TECHNICAL SPECIFICATION
|
LIMITED WARRANTY |
Suitability
This is a popular choice in Nigeria for campus type university radios that are licensed by the state for 20 watts. Using this 20 watt transmitter with our 4 way stacked dipole is a popular choice producing a total EIRP of approximately 80 watts.
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 System
If you're unsure which version suits your needs, this is the recommended choice. It automatically manages audio levels, ensuring that your 20 watt transmitter remains compliant with state regulatory requirements. This makes it an excellent option for beginners.
Even professionals who prefer a hassle-free setup will benefit from this version. Everything is neatly contained in a single enclosure, and the integrated audio processing optimizes loudness while maintaining compliance with legal limits. This ensures that your signal remains strong and competitive without exceeding deviation limits. Striking this balance is essential, and this stereo version with built-in processing achieves it effortlessly.
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The audio inputs follow industry standards: 600 ohm +4 dBu balanced, using XLR connectors for professional-grade connections.
Additionally, this version comes with built-in RDS, allowing listeners to see your station name and other dynamic messages on car radio displays.
This is not just standard RDS—it features fully programmable dynamic RDS. By connecting the transmitter to a PC via USB, you can update RDS data in real time using the USB PC CONTROL function 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
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
On delivery the equipment is ready to plug in and use with any suitable 50 ohm antenna system such as our:
• 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 system package the 20W EIRP system includes this transmitter with a dipole antenna and very low loss LMR400 cable to give you a full system that will comply with the regulations of the European Union and most other countries in the world.
Reliability
Like all our products, we over engineer them, this is no exception. This uses a 45 watt transistor, for 20 watts output. basically you can throw any amount of reflected power at this unit and it will laugh in the face of it. Basically this transmitter, is not super, not ultra, it's HYPER reliable
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.
Configuration
When we test this unit we need to test it at some frequency, it's obviously better if we test it at the frequency you want to us it on, then you can use it straight out of the box on delivery. But if you don't know the frequency, that's okay, the frequency, FM deviation and power is easy to set in a few minutes on the underside panel controls.
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. 1-20 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 | 40W for 20W 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 |
