FlexRadio FLEX-8400
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| Frequency | RX: 30 kHz - 54 MHz, TX: 160-6 m (1.8-54 MHz) |
| Bands | 160m, 80m, 60m, 40m, 30m, 20m, 17m, 15m, 12m, 10m, 6m |
| TX power | 100 W (1-100 watts PEP on 160-6 m (25 watts on AM). It is a 100-watt class HF/6 m transceiver; an amateur license is required.) |
| Modes | SSB, CW, AM, SAM, FM, RTTY, digital |
| Year | 2024 |
| antenna | SO-239 main antenna (50 ohm) plus a BNC receive-only / transverter antenna port |
| lan | Ethernet (LAN) - the primary control connection; the radio is headless and runs from SmartSDR on a PC, Mac, iPad/iPhone or the Maestro console, locally or remotely over the internet via SmartLink |
| mic | Microphone input (ships with the FHM-3 hand mic) |
| transverter | Transverter port (100 kHz-54 MHz, 0 to +10 dBm) |
| reference | 10 MHz external reference input; GNSS/GPS antenna input; optional internal GPSDO |
| dc in | 13.8 VDC (about 23 A on transmit) |
| power req | 13.8 VDC +/-15% (14 V nominal); about 1.7 A on receive and up to 23 A on transmit, so it needs a 25-30 A supply. |
A current, high-performance direct-sampling SDR with excellent receiver numbers (about 115 dB RMDR and over 155 dB dynamic range) and two independent 7 MHz receivers, at the more affordable end of the Flex range. Digital modes need no sound card or cables, it can be operated locally or remotely from a PC, Mac, iPhone, iPad or the Maestro console, and software updates keep adding features. It runs 100 watts on HF and 6 m, with an optional ATU, GPSDO and MARS coverage.
It is headless, so it has no knobs or screen of its own; you run it from a computer, tablet or the separate Maestro console, which is a different workflow from a knob-and-display radio. The full SmartSDR experience is best on Windows (the Mac and iOS clients are paid third-party apps), it needs a stout 13.8 V supply (about 23 A on transmit), and it is a premium purchase before options like the ATU.
The FlexRadio FLEX-8400 is a current direct-sampling SDR transceiver that delivers 100 watts on HF and 6 m with two independent 7 MHz receivers and top-tier receiver performance, all controlled by software rather than front-panel knobs. It suits an operator who embraces a computer- or network-driven station and wants remote operation and a software-defined radio that keeps gaining features; those who want physical controls choose the FLEX-8400M with its built-in display, and traditionalists who prefer knobs may want a conventional transceiver.
The FlexRadio FLEX-8400 is a direct-sampling software-defined radio (SDR) transceiver for HF and 6 meters, part of the FLEX-8000 Signature Series introduced in 2024. Rather than mixing signals down in hardware, it digitizes the antenna directly with a 16-bit, 122.88 Msps converter, which gives it very high dynamic range and low phase noise. It runs 100 watts (25 on AM) across 160 through 6 meters and receives continuously from 30 kHz to 54 MHz in all modes, and a license is required to transmit.
Its defining trait is that it is headless: there are no knobs or screen on the box itself. Instead it is run as a server over the network from FlexRadio's SmartSDR software on a Windows PC, a Mac, an iPad or iPhone, or the dedicated Maestro console, either in the same room or anywhere in the world through SmartLink. That architecture also makes digital modes smooth, since transmit and receive audio stream over the network with no sound card, cables or external interface. Two fully independent receivers, each with up to 7 MHz of spectrum and waterfall, can sit on any two bands at once, and the receiver numbers are excellent, around 115 dB RMDR and over 155 dB dynamic range.
For connection it has a standard SO-239 main antenna jack plus a BNC port for a receive-only antenna or a transverter, an Ethernet jack as the main control link, a microphone input (it ships with the FHM-3 hand mic), a 10 MHz reference input and a GPS antenna input. It runs on 13.8 volts and can draw about 23 amps on transmit, so it wants a 25-to-30-amp supply. Options include an internal automatic antenna tuner, a GPS-disciplined oscillator and a MARS/CAP transmit-expansion module.
It is the more affordable, headless member of the 8000 series; the FLEX-8400M is the same radio with an integrated front-panel display for those who want physical controls. For other software-defined approaches, the open-source Hermes-Lite 2 is a low-cost direct-sampling SDR, while the Elecraft K4 is a direct-sampling SDR that keeps a full front panel of knobs and a touchscreen.