FLEX-6400 2017-11-30T17:44:53+00:00

FLEX-6400  A Real SDR for Every Operator

Both the FLEX-6400™ and FLEX-6400M™ offer the latest direct sampling SDR technology at an economical price for the general HF/6m operator yet they offer excellent performance for chasing DX and contesting. The FLEX-6400 model is designed for the Ham who wants to operate the radio exclusively as a server from PC, laptop, Maestro, Mac, or iOS clients – whether local or remote. Both models share the same game changing band awareness, industry leading phase noise performance, brick wall filters, and legendary audio performance to deliver you the most fun across a wide variety of operating styles.

With a PC, laptop, or Mac client you can utilize up to two 7 MHz spectrum/waterfall displays and independent receivers to revolutionize your view of the bands. Its two receivers can be placed simultaneously on any band and mode with instant QSY between VFOs. Digital mode operation is a dream with no sound cards, cables or boxes needed.

The FLEX-6400M places the most used controls right at your fingertips. Controls are labeled for intuitive operation and designed to minimize hand motion for the most common operations. Occasionally used controls are easily accessible on the large touch screen display bypassing the complexity of multi-function buttons and multi-level menus found on other transceivers. Like modern smartphones and tablets, capacitive touch control is provided on the large LCD display for intuitive pan, zoom, tune, and menu operation.

FLEX-6400 Feature Highlights

  • Native Remote Operation: Using Maestro, PC, Laptop, iPad or iPhone
  • SDR Architecture: Direct Sampling
  • Reciprocal Mixing Dynamic Range (RMDR): 116dB
  • Independent High Performance Receivers: Two (2)
  • Maximum Panadapter Bandwidth: 7 MHz
  • Radio Control Surfaces: Ergonomic tactile controls with touch screen interface
  • Integrated Display: 8-inch 1920x1200 IPS Display
  • External Display: 1920x1200 WUXGA via HDMI interface
  • Antenna Connectors: SO-239x2, BNC XVTRx1, BNC RX-INx1
  • Wideband Frequency Coverage: 30 kHz - 54 MHz
  • Transmit Frequency Coverage: 160-6m amateur bands, 100W nominal output
  • Transverter IF Frequency Coverage: 100 kHz - 54 MHz
  • Full Duplex Operation: Yes
  • Digital Audio Exchange (DAX) Channels: Two (2)
  • DAX IQ Channels/Bandwidth per Channel (DAXIQ): Two (2)

Order NowOrder NowOrder NowOrder NowOrder Now
8-inch Integrated 1920 x 1200 IPS Touch Displaycheckmarkcheckmark
Dual VFO Front Panel Control Setscheckmarkcheckmark
External HDMI Compatible Display Supportcheckmarkcheckmark
Internal 2W Front Speakercheckmarkcheckmark
2 kHz Reciprocal Mixing Dynamic Range1116 dB116 dB116 dB116 dB116 dB
Independent Receivers22448
Panafall Displays (Max)22448
Cableless Digital Audio Channels (DAX/DAXIQ)2/22/24/44/48/4
Receive Only Ports (Base / Including XVTR Ports)1/21/22/42/42/3
Transverter Ports11221
ADC Sampling Rate122.88 Msps122.88 Msps245.76 Msps245.76 Msps245.76 Msps
Frequency Coverage0.03-54MHz0.03-54MHz0.03-54MHz0.03-54MHz0.03-72MHz, 135-165MHz
Spectrum Dynamic Range (Max Zoom)>145 dB>145 dB>155 dB>155 dB>155 dB
100W Output HF - 6mcheckmarkcheckmarkcheckmarkcheckmarkcheckmark
Ultra Low Transmitter Phase Noise & Harmonicscheckmarkcheckmarkcheckmarkcheckmarkcheckmark
Full Duplex RX/TX Operationcheckmarkcheckmarkcheckmarkcheckmarkcheckmark
Full Break-in QSKcheckmarkcheckmarkcheckmarkcheckmarkcheckmark
Integrated Remote Operationcheckmarkcheckmarkcheckmarkcheckmarkcheckmark
Maestro, PC, MAC, iPhone & iPad Clients2checkmarkcheckmarkcheckmarkcheckmarkcheckmark
630m and 2200m IF Coveragecheckmarkcheckmarkcheckmarkcheckmarkcheckmark
D-STAR with Optional ThumbDVcheckmarkcheckmarkcheckmarkcheckmarkcheckmark
GPS Disciplined Oscillator Optioncheckmarkcheckmarkcheckmarkcheckmarkcheckmark
External 10MHz Reference Inputcheckmarkcheckmarkcheckmarkcheckmarkcheckmark
Integrated Automatic Antenna TunerOptionalOptionalcheckmarkcheckmarkcheckmark
Continuous MARS/CAP TX CoverageOptionalOptionalOptionalOptionalcheckmark
3rd Order Ham Band Preselectorscheckmarkcheckmarkcheckmark
Enhanced 7th Order Contest Band Preselectorscheckmarkcheckmark
Simultaneously Receive on Two Antennas ( e. g. 20m & 6m)checkmarkcheckmarkcheckmark
Synchronous Diversity Receptioncheckmarkcheckmarkcheckmark
Enhanced Panadapter Zoom (1.6 Hz RBW)checkmarkcheckmarkcheckmark
HD Zoom View Eight Bandscheckmarkcheckmarkcheckmark
Dedicated Balanced Audio Input (mic or line)checkmarkcheckmarkcheckmark
4m and 2m IF Coveragecheckmark
Ultra High Stability Oven Controlled Oscillator (OCXO)checkmark
Simultaneous Receive on 2m and HFcheckmark

1QST April 2015 Review; FLEX-6700 with 20dB Preamp On
2Mac and iPAD clients provided and supported by third-party developers

Information subject to change without notice.

Receiver Specifications

  • Receiver Architecture: Direct Digital Sampling
  • Spectral Capture Units (digitizers): One (1)
  • Maximum Slice Receivers: Two (2)
  • ADC Resolution: 16-bits
  • ADC Sampling Rate: 122.88 Msps
  • Wideband Frequency Coverage: 30 kHz - 54 MHz
  • DAX IQ Channels / Bandwidth Per Channel: Two (2)
  • DAX Audio Channels: Two (2)
  • Amateur Band Preselector Coverage: 3rd order
  • 1/2 kHz Reciprocal Mixing Dynamic Range (RMDR): 110/116 dB
  • Spurious and Image Rejection Ratio: 80 dB or better

Spectrum/Waterfall Display Specifications

  • Maximum High Resolution Spectrum Displays: Two (2)
  • Panadapter Bandwidth: 5 kHz - 7 MHz
  • Spectrum Dynamic Range (max zoom): > 145 dB
  • Spectrum Resolution Bandwidth (min): 5.85 Hz
  • Integrated Touch Panel Display Size (diagonal)1: 8" (20.3 cm)
  • Integrated Display Resolution1: 1920x1200
  • External Display Resolution/Connection1: 1920x1200/HDMI

Transmitter Specifications

  • Transmitter Architecture: Direct Digital Up-conversion
  • Modulation System: Digital Low Power at Carrier Frequency
  • RF Output Power: 1-100W nominal SSB, CW, FM, RTTY, Digital; 1-25W nominal AM
  • Amateur Band Coverage at Rated Power Output: 160m – 6m
  • Transverter IF Output Power: +0 dBm Typical; +10 dBm max
  • Transverter IF Frequency Coverage: 100 kHz - 54 MHz
  • DAX Transmit Channel: Yes
  • Carrier / Unwanted Sideband Suppression: <-80 dBc typ / <-80 dBc typ
  • Spurious Emissions 1.8 - 50 MHz Amateur Bands: <-55 dBc; -65 dBc 6m
  • Transmit Bandwidth: Default 100-2900 Hz (Variable 50-10000 Hz)
  • Microphone Connector: Pseudo Balanced 1/8" TRS
  • Microphone Impedance: 600 Ohms Nominal (200-10kΩ)

Optional Antenna Tuner Specifications

  • Matching Range 80m - 10m: Optional, 8.3 Ohms - 300 Ohms
  • Matching Range 160 and 6m: Optional, 16.7 Ohms - 150 Ohms

General Specifications

  • USB 2.0 Ports (peripheral control): Two (2)
  • Internal 10 MHz Reference Clock Stability: 0.5ppm TCXO (0-50C)
  • Emission Modes: USB, LSB, CW, RTTY2, AM, Synchronous AM, FM, NFM, DFM, FreeDV2
  • Frequency Resolution: 1 Hz min.
  • Antenna Connectors: SO-239x2, BNC XVTRx1, BNC RX-INx1
  • Antenna Impedance (w/o tuner): 50 Ohm Unbalanced


  • Power Supply Requirements: +13.8V DC nominal ±15%
  • Current Drain (Receive/Transmit Max): 1.7A / 23A @ 13.8V


  • 6400 Height/Width/Depth: 7" (17.8 cm) with feet / 14" (35.5 cm) / 12" (30.5 cm)
  • 6400M Height/Width/Depth: 7" (17.8 cm) with feet / 14" (35.5 cm) / 13.125" (33.3 cm)
  • 6400 Weight: 9.5 lbs (4.3 kgs)
  • 6400M Weight: 10.5 lbs (4.8 kgs)
  • Operating Temperature: 0 to +50 degrees C; +32 to +122 degrees F


  • Antenna Tuning Unit (ATU); 3:1 SWR
  • GPS Disciplined Oscillator; 5x10-12 over 24 hours
  • MARS/CAP Coverage Filter Bank
  • ThumbDV module for D-Star mode

Specifications subject to change without notice.
1FLEX-6400M model.
2RTTY and other digital modes requires 3rd party software over DAX channels.

The following product datasheets are available for download.

FLEX-6400 Product Brochure (1.9 MiB)

FLEX-6400 And FLEX-6600 Bracket Install Guide0.8 MiB190
FLEX-6400 and FLEX-6600 Hardware Reference Manual1.8 MiB1840
FLEX-6400 Product Brochure1.9 MiB4027
FLEX-6400(M) And FLEX-6600(M) GPSDO Installation Guide1.7 MiB449
FLEX-6400M & FLEX-6600M Quick Start Guide3.9 MiB1882
FLEX-6400M and FLEX-6600M User Guide8.1 MiB2464

SmartSDR V2.2.8 Release Notes0.2 MiB1093
SmartSDR V2 ChangeLog25 KiB422
SmartSDR V2.2.8 Installer49.4 MiB3595

A comprehensive listing of software for the FLEX-6400 can be found on the Downloads page.

FLEX-6400 Signature Series 2-Year Limited Hardware Warranty

This Limited Warranty is effective as of the date of first purchase by the consumer. Original equipment hardware warranties and manufacturer support for FlexRadio Systems products applies only to the original purchaser and are not transferable unless a Warranty Transfer agreement is purchased from FlexRadio Systems. Before sending in your product for service, it is recommended that you query the FlexRadio Community to make sure your issue is not easily resolved. If you still have an issue, submit a request for support via the FlexRadio HelpDesk. Once you are assigned an incident or ticket number, one of our Technical Support Engineers will determine if the issue your product is experiencing requires service or repair and will either issue you an RMA (Return Material Authorization) number for service in Austin, TX or refer you to another authorized Service Center. Any product returned for service that is out of warranty or has had its warranty voided is subject to a one (1) hour diagnostic bench charge. This charge will be applied to any work performed.

What is Covered:

During the first thirty (30) days after the date of shipment, FlexRadio Systems will fully repair or replace a defective product at their discretion. For the remaining two (2) years after the date of shipment, FlexRadio Systems will replace defective parts free of charge (post-paid) for transceiver components only. Any replacement hardware parts will be warranted for the remainder of the original warranty period or ninety (90) calendar days from the date of installation or repair, whichever is longer. FlexRadio Systems will also correct any failure caused by defective parts and materials. You must send the unit at your expense to FlexRadio Systems. FlexRadio Systems will pay return shipping to the country of purchase.

What is Not Covered:

This Limited Warranty as it pertains to the transceiver or radio components does not cover repair or damage caused by (1) misuse, negligence, exposure to excessive RF energy or user modifications; (2) any performance or operational malfunctions involving non-FlexRadio Systems accessory equipment; (3) connection to improper or unstable voltage supply; (4) improper execution of hardware calibration or test routines; (5) the incorrect installation of any and all cables connected to the radio by the user; (6) the use of third-party software applications or hardware that directly or indirectly controls radio functions and/or operating state by utilizing a communication or control protocol, such as, but not limited to CAT or I2C commands or (7) random acts of nature such as flood, fire, water, weather related storm, lightning or electrostatic discharge damage.

Limitation of Incidental or Consequential Damages:

This warranty does not extend to non-FlexRadio Systems equipment or components used in conjunction with our products. Any such repair or replacement is the responsibility of the customer. FlexRadio Systems shall not be liable or responsible for reimbursement for any special, indirect, incidental or consequential damages, including but not limited to any loss of business or profits, loss of property, loss of revenue, loss of use, loss of data, inconvenience or cost of unauthorized service.

Purchase the FLEX-6400 or FLEX-6400M Software Defined Radios and accessories directly from our Online store or from one of our authorized FlexRadio Distributors for our international customers.

Purchase a FLEX-6400M via the Online Store Today! Starting at $2999.

Purchase a FLEX-6400 via the Online Store Today! Starting at $1999.

For more information contact FlexRadio Systems Amateur Sales.