The FLEX-6400 and FLEX-6400M are advanced 100W HF transceivers designed for amateur radio enthusiasts, covering shortwave bands from 160 to 10 meters and the 6-meter band. A standout feature of these models is their two independent receivers, which allow operators to engage in split-mode DXing or monitor multiple bands and modes during contests. The entire duplex crossband operation further enhances versatility, making it easier to manage complex communication scenarios.

Equipped with direct sampling SDR technology, the FLEX-6400 series boasts a sampling rate of 122.8 MHz and a 16-bit AD converter, yielding an impressive RMDR value of 115 dB at a 2 kHz distance. This high-performance digital architecture provides users a spectrum width of up to 7 MHz, facilitating the simultaneous observation of various amateur radio bands. The receiver operates within a 30 kHz to 54 MHz frequency range, while the transmitter is restricted to the designated amateur bands. The inclusion of a preselector with 3-pole band filters enhances large signal selectivity, and a low-noise oscillator ensures optimal receiver performance. For those requiring precise timing, a 10 MHz reference clock input compatible with an optional GPSDO and a transverter output and RX input for VHF band operations are available.

On the transmission side, the FLEX-6400/FLEX-6400M delivers 100W of PEP power (25W for AM), with unwanted by-product suppression exceeding 60 dBc. The transverter output can be adjusted from 0 to +10 dBm, ensuring flexibility in power management. The transmitter is confined to the amateur radio bands relevant to the user's location, and an optional automatic antenna tuner can efficiently correct mismatches up to a 3:1 SWR, further optimizing operator performance.