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 still in doubt, check the comparison chart further below. You can also drop us a message/e-mail or contact us via Skype for additional info.
Small community stations in remote areas, far from urban centers
STMAX3015+ works best for these since it comes 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. You can mount one of these on the top of these amplifier modules, this will form a complete Stereo RDS FM transmitter. Audio quality is acceptable, but not as good as MAXPRO8015 + SE8000 for example, spurious level is not suitable for professional setups as DDS digital modulator creates some in-band artefacts about -50dBc down. If you’re looking for a low cost solution and just want to play with radio a little bit, get one of these. Set the power limit jumper into 1W position, choose a free unused frequency and it is very unlikely that you will ever get in trouble.
Small community stations that require spurious levels to be >65dBc
If your signal needs to be clean but 15W is all you need, MAXPRO2015+ works best. You will also need a separate stereo encoder oraudio processor with MPX output. The added benefit is that you can now also use MPX STL wireless link.MAXPRO2015+ can be used as a pallet amplifier driver (it has PWR/SWR inputs), but it is a bit less convenient than its larger brother the MAXPRO8015 which come with DIGIAMP interface.
Large stations that require spurious levels to be >65dBc or more
MAXPRO8015+ works best. You will also need a separate stereo encoder or audio processor with MPX output.. The added benefit is that you can now also use MPX STL wireless link. Both are equipped with DIGIAMP interface, the 7015+ is almost identical but is cleaner than the 6015+. MAXPRO8015+ is further improved and also supports MAXLINK II so when interfacing with SE8000 you don’t need to solder at all. Any of these can drive any amplifier up to 10KW and more. Both 6015+ and 7015+ support the new SE7000+ DSP stereo encoders and the new large 4×16 LCD display with rotary encoder. MAXPRO8015+ works best with SE8000 DSP+ and really shines in this combo. Add RDS encoder (listed on that same page) and you’ve got a perfect radio exciter.
MAXPRO8015+ V5 (SB)
New special version with audio response down to the lowest BASS frequencies.
Here is a quick comparison chart between different types of our FM exciters:
| Name | MAXPRO2015+ | STMAX3015+ series | MAXPRO8015+ SB |
|---|---|---|---|
| Available today | Yes | Yes | Yes |
| 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 (54-68 and 76-90MHz on request) |
| Output power | 15W | 15W/25W/35W/50W | 15W/25W/50W/100W |
| Supply voltage | 12-15V | 12-15V | 12-15V |
| PLL step size | 100 kHz (down to 50KHz on request) | 100 kHz (down to 1KHz on request) | 100 kHz (down to 50KHz on request) |
| Antenna connector | BNC | BNC | BNC or MCX with N pigtail |
| Modulation type | Standard MPX input | L/R input | Standard MPX input |
| VCO type | Standard VCO + PLL | DDS digital | Standard VCO + PLL, improved |
| Spurious output | <65dBc | <50dBc | <80dBc |
| Built-in stereo encoder | No, requires SE2000, SE5000 or SE8000 (SE7000 not supported) | Yes | No, requires SE2000, SE5000 or SE8000 (SE7000 not supported) SE8000 DSP+ recommended! |
| MAXLINK support | Yes | Yes | Yes, also MAXLINK II (no MPX cable needed) |
| Built-in RDS | No, requires external | Yes | No, requires external |
| What kind of STL link can be used | MPX or regular split audio channels | Split audio channels only | MPX or regular split audio channels |
| Digiamp support | No, but it has input for external power and swr | Yes | Yes |
| RDS control | Via PC aplication, requires RDS encoder | Directly from LCD display or via PC application | Via PC aplication, requires RDS encoder |
| PC remote control | CyberMaxFM+ program | CyberNanoFM+ program | CyberMaxFM+ program |
| Support for new large 4×16 LCD | No | Yes | Yes |
| Suitable for: | Low cost solution with a clean signal | Low cost Stereo + RDS solution, not the best audio quality, all functions adjustable from LCD display | Very clean signal for pro solutions, requires Stereo/RDS encoder (or MPX source), super bass audio fix. |
A few words regarding some of the typical properties:
PLL step size:
No legal radio stations exist outside 200KHz steps so 100KHz is more than enough for a PLL step size. Many car receivers have fixed 200KHz step size.
RDS:
Radio data system, displays radio station name on the display of receiver
DIGIAMP support:
When building a larger transmitter which consists from exciter module, amplifier module and output filter, this interface simply plugs into our filter to provide a host of signals to the exciter. Exciter can display those on the LCD. These include power, swr, temperature, amplifier voltage and others.
MAXLINK support:
This interface connects stereo encoder to the exciter module. It carries power (+12V) and control signals (I2C and stereo/mono). Supports SE2000, 5000, 7000.
MAXLINK II support:
This extended interface connects stereo encoder to the exciter module. It carries power (+12V) control signals (I2C and stereo/mono), VU meter signals and MPX signal. Supports SE8000 DSP+. At this time only MAXPRO8015+ supports this interface.