One of the first steps when building your own FM transmitter from modules will be the choice of exciter module. Below are a few typical scenarios that will help you decide. If you are lost and don’t know where to start consider reading this guide for setting up drive in cinema FM radio written by PCS Electronics. In contains interesting information to help you get started and will be valuable also for other situations. Typically scenarios in the field:
Small community stations in remote areas, far from urban centers or critical infrastructure, with limited budget. STMAX9015 or STMAX3015 micro work best for these since they come with built-in stereo encoder and RDS. This reduces both cost and complexity. It can also be easily programmed via LCD without the need for PC to set the RDS parameters. Audio quality is pretty good. Spurious level is not suitable for professional setups as integrated digital modulator creates some in-band artefacts about -50dBc down. If you’re looking for a simple solution where those issues are not a factor (remote rural area) do get one of these, you will not be disappointed.
Small and large stations that require compliance with standards and high signal purity MAXPRO8015+ works best. You will also need a separate SE8000 DSP+ stereo encoder or Audio processor with MPX output. It is equipped with DIGIAMP interface and also supports MAXLINK II so when interfacing with SE8000 or amplifier you practically don’t need to solder at all. Any of these can drive any amplifier up to 10KW and more. Used in our high quality CE certified CyberMaxFM+ SE+ and BE+ series.
Here is a quick comparison chart between different types of our FM exciters:
| Name | STMAX3015 +micro Micro Budget series | MAXPRO8015+ SB Professional series | STMAX/9000+ series Low Budget series |
|---|---|---|---|
| Available today | Yes | Yes | Yes/Soon |
| Frequency range | 87,5-108 MHz (54-68 and 76-90MHz on request) | 87,5-108 MHz (76-90MHz on request) | 87,5-108 MHz (76-90MHz on request) |
| Output power | 15W, 25W | 15W, 25W. 50W, 100W | 15W/25W/50W/100W |
| Supply voltage | 12-15V | 12-15V | 12-15V |
| PLL step size | 100 kHz (50KHz) | 100 kHz (50KHz) | 100 kHz (50KHz |
| Antenna connector | MCX (N, BNC, SO239 pigtails available) | BNC female | MCX (N, BNC, SO239 pigtails available) |
| Modulation type | L/R input (2xRCA), with input board also XLR, USB and AES/EBU | Standard MPX, with MPX input board or Stereo encoder also L/R input (2xRCA), with input board also XLR, USB and AES/EBU | L/R input (2xRCA), with input board also XLR, USB and AES/EBU |
| VCO type | Integrated digital modulator | Super low noise VCO + PLL | Integrated digital modulator |
| Spurious output | ~-50dBc | >-83dBc | ~-50dBc |
| Built-in stereo encoder | Yes | No, requires SE8000 DSP+ stereo encoder! | Yes |
| Digiamp | Yes partial | Yes full | Yes full |
| Built-in RDS | Yes | Pro plug-in available | Yes |
| RDS control | Directly from LCD display or via PC application | Via PC application (SE), requires RDS encoder. Web remote control when used with OLED display (BE). | Directly from LCD display or via PC application |
| PC remote control | CyberNanoFM+ program | CyberMaxFM+ program (SE series) or web interface (BE series OLED display) | CyberNanoFM+ program, web interface with OLED display |
| MPX input | No | Yes | No |
| Suitable for: | Low cost Stereo + RDS solution, all functions including RDS adjustable from LCD display. For remote areas. | Very clean signal for pro solutions, requires Stereo/RDS encoder | Low cost Stereo + RDS solution, all functions including RDS adjustable from LCD display. For remote areas. |
For all other considerations and questions do not hesitate to contact us.
We have observed that many of our new inexperienced customers struggle with simple concepts and wiring 2-3 boards can sometimes be a problem. We have prepared a list of example packages which come with exciter, stereo encoder and sometimes also RDS and IO board. All these boards need to be wired together, installed into enclosure and connected to antenna and power supply to form a working transmitter. We strongly encourage you to install the boards in an enclosure, preferably metal enclosure with a small fan (40×40 should work). Running without a small fan or metal enclosure does not insure sufficient cooling and is not recommended.
We will list these example packages below with their main characteristics, you can read more about the used components in their respective listings (they are all available for purchase on this website).
Pro level 15W stereo FM transmitter with RDS and remote control via USB Contains: –MAXPRO8015+ SuperBass FM exciter with LCD (2×16 + rotary encoder button) – SE8000DSP+ stereo encoder – RDSMAX8000 mini RDS board – IO board with 3 BNC inputs – Pre-drilled LCD panel (rotary button 2×16) for easy assembly – Pre-drilled back panel for SE8000 for easy assembly – Pre-drilled back panel for IO board for easy assembly Specifications: – 15W, operates from 12-15V DC (2.5A) – BNC antenna connector – Excellent stereo sound – Fantastic stereo separation – DSP sound processor (adjustable pilot via LCD etc) – RDS with PS, RT and all other functions – Two RCA audio inputs – Two XLR audio inputs – Digital audio input – USB – BNC connectors for MPX in, MPX out and 19KHz pilot (TTL) – Remote control with PC via USB or RS232 for full control over transmitter functions Requires: – Antenna and 15V mains power supply – Enclosure
Pro level 25W stereo FM transmitter with RDS and remote control via USB Contains: –MAXPRO8025+ SuperBass FM exciter with LCD (2×16 + rotary encoder button) – SE8000DSP+ stereo encoder – RDSMAX8000 mini RDS board – IO board with 3 BNC inputs – Pre-drilled LCD panel (rotary button 2×16) for easy assembly – Pre-drilled back panel for SE8000 for easy assembly – Pre-drilled back panel for IO board for easy assembly Specifications: – 25W, operates from 12-15V DC (4A) – BNC antenna connector – Excellent stereo sound – Fantastic stereo separation – DSP sound processor (adjustable pilot via LCD etc) – RDS with PS, RT and all other functions – Two RCA audio inputs – Two XLR audio inputs – Digital audio input – USB – BNC connectors for MPX in, MPX out and 19KHz pilot (TTL) – Remote control with PC via USB or RS232 for full control over transmitter functions Requires: – Antenna and 15V mains power supply – Enclosure
Pro level 400W stereo FM transmitter with RDS and remote control via USB Contains: –MAXPRO8015+ SuperBass FM exciter with LCD (4×16 + rotary encoder button) – SE8000DSP+ stereo encoder – RDSMAX8000 mini RDS board – IO board with 3 BNC inputs – 400W AMPBOX with high-power fans – DCDC to generate 15V for exciter – Pre-drilled LCD panel (rotary button 4×16) for easy assembly – Pre-drilled back panel for SE8000 for easy assembly – Pre-drilled back panel for IO board for easy assembly – 1800W mains power supply (220V required for full power) Specifications: – 400W, operates from 220-240V mains – 7/16 antenna connector – Excellent stereo sound – Fantastic stereo separation – DSP sound processor (adjustable pilot via LCD etc.) – RDS with PS, RT and all other functions – Two RCA audio inputs – Two XLR audio inputs – Digital audio input – USB – BNC connectors for MPX in, MPX out and 19KHz pilot (TTL) – Remote control with PC via USB or RS232 for full control over transmitter functions Requires: – Antenna and mains power – Enclosure, best put it in 2H rack, – Mains cable and mains switch –Maybe some normal strength size 80×80 fans
Pro level 1000W stereo FM transmitter with RDS and remote control via USB Contains: –MAXPRO8015+ SuperBass FM exciter with OLED display with web control interface – SE8000DSP+ stereo encoder – RDSMAX8000 mini RDS board – IO board with 3 BNC inputs – 1000W AMPBOX with high-power fans – DCDC to generate 15V for exciter – 1800W mains power supply (220V required for full power) – Pre-drilled LCD panel (rotary button 4×16) for easy assembly – Pre-drilled back panel for SE8000 for easy assembly – Pre-drilled back panel for IO board for easy assembly Specifications: – 1000W, operates from 220-240V mains – Full remote control via WEB browser – UECP compatible RDS – 7/16 antenna connector – Excellent stereo sound – Fantastic stereo separation – DSP sound processor (adjustable pilot via LCD etc.) – RDS with PS, RT and all other functions – Two RCA audio inputs – Two XLR audio inputs – Digital audio input – USB – BNC connectors for MPX in, MPX out and 19KHz pilot (TTL) – Remote control with PC via USB or RS232 for full control over transmitter functions Requires: – Antenna and mains power – Enclosure, best put it in 2H rack, – Mains cable and mains switch –Maybe some normal strength size 80×80 fans
Recommendations for assembly of transmitters: 1. Install the boards into metal enclosure, fan is recommended for exciter 2. If full power is too much, set power limit jumper to desired setting with jumpers (you can select 1W, 2W, 3W, 4W, 5W, 6W, 7W, 8W, 9W, 10W….or 15W) 3. Connect antenna, audio input and supply voltage 4. You can change power and frequency with LCD as desired 5. With mains operated units please beware of high voltage, it can be deadly. Use inline mains fuse and mains filter.
How does this work with driving amplifiers? 8015+ is easy to setup for driving a pallet amplifier: – Set power limit jumper to desired drive power setting with jumpers (you can select 1W, 2W, 3W, 4W, 5W, 6W, 7W, 8W, 9W, 10W….or 15W) – Connect the SWR and power reading voltage to PWR and SWR pins (2015) or just connect DIGIAMP cable to our filter (8015) – Set the power meter voltage sensitivity (trimmers on directional coupler – usually on filter) as you wish and the exciter will never drive your amp beyond preset value.
What is the Predrilled LCD front panel? – This is a rectangular piece of aluminum with predrilled holes for LCD display, buttons and LED diodes. These exist also for stereo encoder and IO board. It also has 4 holes in the corner so you can easily mount this to your case. This makes it much easier to mount the transmitter into a nice looking case (eliminates the hard work with the LCD). This is of course an optional item.
To look for a suitable antenna check: here. To look for a suitable coaxial cable check: here.
Please ensure that you always run this or any other transmitter with antenna or dummy load attached.
