Seacom SEA 245. This runs 150W CW or SSB between 1.6 MHz and 30 MHz. It is a dual conversion system with the first IF at 45 MHz and the second at 40 kHz. The 40 kHz IF is run through an A/D and then into a DSP where final filtering and demodulation are handled in a DSP. On the transmit side, the DSP generates the SSB (or other) signal at 40 kHz. It is then upconverted to 45 MHz, and then to the final transmit frequency. The high first IF provides good image rejection with broad band RF filters. In fact, the same band pass filters that are used on the transmit side are used on the receive side.