DRMAX is a DRM compatible AM Medium Wave DDS-based (better than PLL stability) radio broadcast board that offers great audio quality, 1KHz frequency step selection (for both 10KHz US and 9KHz EU steps) using only four keys. You connect audio and send it wirelessly using whip antenna, distance varies with surrounding conditions, RF PEP output 500mW (at 50 Ohm) maximum over the entire band. FULL BROADBAND DESIGN, no variable caps to adjust! Reception is on a regular DRM radio set anywhere from 530KHz to 1700KHz (special model available for 510-2000KHz covering 160m band) and minimum step of 1KHz.
It has two independently adjustable audio inputs, for I and Q channels that accept the output of a PC audio card encoded by appropriate software such as SPARK DRM Encoder.
You can change the broadcast frequency on the fly using incremental speed tuning. Just press the UP or DOWN button to go up or down the frequencies. After ENTER is pressed the DDS is re-programmed with the new transmission frequency. The power-on frequency and all other settings can be saved to the built-in non-volatile memory at the press of a key.
It has an excellent spectral purity with harmonics rejection better than -50dBc (upper half band) as can be seen in a Spectrum Analyser, out-of-band spurious output better than -60dBc, and accuracy of the lock-on frequency better than +/- 0.5Hz. You can manually turn the RF output on/off, or use the built-in real-time clock to set a daily or weekend schedule for automatic on/off at a specific time. With this option, one can leave the unit at a remote site and have it operate only for the specified hours.
The device requires 24V (International) @350mA maximum.