2.5 Watt ERP FM Transmitter System

Which Version Do You Need?

MPX System
This is the low cost version, but is not intended for the novice or beginners. The audio input is raw MPX without any audio limiting or stereo coder circuitry, this must be provided externally in accordance with the recommendations of http://www.aareff.com/ETR132.pdf

Stereo System
This is identical to Mono/MPX version but with a stereo coder built in. RDS cannot be used with this. Again it does not include audio limiting, so it's not recommended for the novice or beginner. External limiting need to comply with the recommendations of http://www.aareff.com/ETR132.pdf

Stereo and Audio Processing System
Most small radio stations and beginners will use this version, this is because it includes audio processing circuitry and suitable limiting to keep the transmitter in compliance with the maximum bandwidth permitted by the international regulations. There is also access to the MPX in and out on the back panel which allows all known RDS units to be connected.

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5 Year Warranty

On delivery the equipment is ready to plug in and use. This transmitter is so reliable we can give it a 5 year warranty and our reputation of high reliability without any hesitation.

What's In The Delivery Package?

On delivery this system is complete with all cables, leads and plugs soldered on. Just mount the antenna as high and as clear as possible, plug it all together, switch on and you are on air! The delivery package includes the following:

The MPX and Stereo System is delivered with the compact transmitter and the Stereo with Audio Processing System is delivered with the 19 inch rack transmitter shown in photo above.
Worldwide Power Supply for 90-260V AC 47-63Hz
20m LMR400 Cable with Plugs Fitted
2 Way Stacked Dipole Antenna 4.8dBi Gain


The Stereo with Audio Processing System version of this equipment can be used without any additional equipment and will be in compliance with nearly all regulators in the world. The MPX System will need additional audio limiting and stereo coding equipment and the Stereo System will will need additional audio limiting equipment. All versions with the correct additional equipment comply with EU Telecommunications ETS 300384, EMC EN 301 489-11 and Safety LVD 2006/95/ and also ITU-R BS.450-3 (11/01) FM Broadcasting at VHF. If you are a novice or beginner and you don't have any knowledge of audio limiting, processing and compression you will need to purchase an additional audio limiter at http://www.aareff.com/en/fm-transmitter-limiter/ version ALSB to maintain compliance with the regulations.

Technical Specification

Power Requirements 15 VDC or 90-260 VAC 48-62 Hz
Transmitter RF Output 1W +/- 0.5 dB
Antenna RF Output 2.5W ERP +/- 0.5 dB
Antenna and Cable Gain Gain 0dB (Dipole with 12 m RG58 Cable)
RF Channels 100 KHz steps from 87.5 to 108.0 MHz
Deviation Sensitivity Stability +/-2% max
RF Harmonics >75 dB rtc
RF Spurious >63 dB rtc
Out of Lock Suppression >63 dB rtc
Freq Adj. Accuracy +/- 50 Hz
Fine Freq. Adj. > +/- 1000 Hz
RF Frequency Stability Extreme +/- 2 KHz from -20 to +40 Deg C Normal +/- 300 Hz at 20 Deg C
RF Output Connector BNC
Audio Input Level 0.775 V rms for +/- 75 KHz
Audio Connectors Phono/RCA type unbalanced sockets
Pre-emph (50 uS/ 75 uS/ None) Selectable
Audio Signal to Noise Ratio 80 dBu
Audio Freq. Response Stereo +/- 0.5 dB 30 Hz to 15 KHz MPX +/- 0.5 dB 30 Hz to 76 KHz
Audio Distortion Better than 0.02 % THD at Modulator
Stereo Crosstalk Better than 35 dB
Stereo Pilot Tone 19 KHz
Pilot Tone Stability 0.2 Hz


On all the different versions any frequency between 87.5 to 108MHz can be accurately programmed on the dip switches accessible from the underside panel in a few minutes. Expensive test equipment is NOT required, set up is a simple task using the LED's on the front panel. The transmitter operates from a 15V DC supply or the supplied AC adapter (90-260 VAC). This makes it suitable for use on a standard power pack or automobile power system anywhere around the world.