FlexRadio 8400ATU Signature Series SDR Transceivers offer the latest in high-performance, direct sampling software-defined radio (SDR) technology designed for the HF and 6-meter amateur bands. Designed for hams who operate exclusively via remote access, the FLEX-8400 is engineered as a server-based SDR transceiver. It supports SmartSDR clients on Windows, Mac, iOS, and Maestro, allowing seamless control from virtually anywhere. With dual independent receivers and full duplex cross-band capability, it’s ideal for DXing, contesting, and digital modes—no external sound cards or interfaces required. The integrated automatic antenna tuner (ATU) is designed to match antennas with up to 3:1 SWR on 80–10 meters and up to 2.5:1 SWR on 160 and 6 meters.

Using a PC, laptop, or Mac client, the FLEX-8400 supports up to two 7 MHz spectrum/waterfall displays and independent receivers, providing enhanced band visibility. Both receivers can operate simultaneously on any band and mode, with instant QSY between VFOs. Digital mode operation is streamlined—no sound cards, cables, or external interfaces required. The radio delivers advanced band awareness, low phase noise, brick wall filters, and high-quality audio performance to support a wide range of operating styles.

FlexRadio’s SmartSDR™ software is compatible across the entire FLEX-8000 Signature Series, supporting ongoing software enhancements. SmartLink™ technology enables remote access to your radio from any SmartSDR-compatible client using just a login and password—including on iPhone.

What’s in the box:

• (1) Flex-8400

• (1) FHM-3 Hand Mic

• (1) DC Power Cable

• (1) Ethernet Cable

• (1) Quick Start Guide

• (1) GNNS/GPS Antenna

Key Features:

Integrated Automatic Antenna Tuner: Designed to Tune antennas up to 3:1 SWR or better on 80-10m and 2.5:1 SWR on 160m and 6m.

Direct Sampling SDR Architecture: The FLEX-8400 uses a 16-bit, 122.88 Msps direct sampling ADC, delivering high dynamic range and ultra-low phase noise. This architecture enables superior signal clarity and eliminates the need for traditional analog conversion stages.

Dual Independent Receivers with Full Duplex: Operate two independent receivers simultaneously on any band and mode, with full duplex cross-band capability. Each receiver supports up to 7MHz of real-time spectrum and waterfall display, ideal for contesting, DXing, and digital modes.

Integrated Remote Operation with SmartLink™: SmartLink™ allows seamless remote access from any SmartSDR-compatible client—Windows, Mac, iOS, Maestro—using only a login and password. No complex setup or VPN is required, enabling operation from virtually anywhere.

Additional Features and Specifications:

• Integrated Automatic Antenna Tuner: Designed to Tune antennas up to 3:1 SWR or better on 80-10m and 2.5:1 SWR on 160m and 6m.

• RX Frequency Coverage: 30 kHz – 54MHz

• TX Band Coverage: 160-6M / 1.8-54MHz

• Transmit Power: 100W (25W AM)

• Modes Supported: SSB, CW, AM, SAM, FM, RTTY, DIGITAL

• Reciprocal Mixing Dynamic Range: 110/115dB at 2kHz

• Dynamic Range: >155dB

• ADC: 16-bit / 122.88 Msps (Mega Samples Per Second)

• Receivers: 2 independent band/mode

• Transverter Ports: 1 (100kHz – 54MHz / 0 to +10dBm)

• Receive Only Ports: (Base/Including XVTR Port):1/2

• Amateur Band PreSelectors: 3^rd Order

• Antenna Tuner: Optional, 3:1 SWR range (Sold separately)

• GPSDO: Optional, 5×10 -12 stability over 24 hours (Sold separately)

• Reference Input: 10MHz external

• Performance: Best in Class

• RMDR 115db

• No listening fatigue

• Ultra-Low Phase Noise

• Full Break-in QSK CW

• Full Duplex Cross-Band Operation

• Brick Wall Filters

• Stunning transmit audio

• Power Supply: 13.8VDC ±15%

• Dimensions:(WxHxD) 6.74 × 14.0 × 13.25in

Note: RTTY and other digital modes use 3rd party software over DAX channels.