FlexRadio FLEX-8600M firmware v4.2.18

Page 1 | Copyright 2026 FlexRadio, Inc. | SmartSDR v4.2.18 Release Notes | SmartSDR+ v4.2.18 Release Notes Version Release Date Release Theme/Title 4.2.18 2026-04-28 DAXv2. 64-bit SmartSDR, DAX, and CAT​.

Band Plan & RX Filter Presets SmartSDR Basic™ and SmartSDR+™ v4.2.18 is an Early Access software and firmware release for Aurora™, FLEX-8000™, and FLEX-6000™ series SDRs, as well as Maestro™.

This version supersedes all previous SmartSDR releases and is available to all users.

Access to new features introduced in this release is limited to SmartSDR+ Early Access feature license holders unless otherwise noted.

Important Release Information Before upgrading, please review all sections marked as IMPORTANT for upgrade prerequisites and other critical information.

There are multiple important notices associated with SmartSDR v4.2.18.

You should understand these changes before upgrading from a previous version of SmartSDR.

Please open a HelpDesk support ticket if you have questions.

Important Notice: It is highly recommended to uninstall all previous versions of SmartSDR before upgrading to SmartSDR v4.2.18.

Prior to installing SmartSDR v4.2.18, it is strongly recommended that all previous versions of SmartSDR be completely uninstalled from your PC, including DAX and the FlexVSP driver.

SmartSDR v4.2.18 introduces a new software architecture that includes updated DAX and FlexVSP drivers.

Retaining older versions on your system may result in installation conflicts or degraded performance.

For best results, ensure all earlier SmartSDR versions (v4.1.5 and below) are fully removed before proceeding with the installation.

Refer to the HelpDesk article “How to Install SmartSDR v4.2.18” for detailed uninstallation and installation instructions.

Important Notice: SmartSDR for Windows supports both x64 and ARM processor platforms.

We are excited to announce expanded platform support for SmartSDR for Windows, DAX, and CAT, including their respective audio and virtual comm port drivers, with the introduction of native compatibility for both x64 (64-bit) and ARM-based processors.

These new features are available for all users.

The x64 version of SmartSDR for Windows replaces legacy 32-bit support, aligning with modern Windows standards and improving overall system efficiency.

This enhancement ensures that SmartSDR can take full advantage of the evolving Windows hardware ecosystem.

When downloading SmartSDR for Windows, make sure that you select the correct installer that aligns with your PC's processor architecture by referring to the HelpDesk article Which SmartSDR Installer Do I Need to Download?

Important Notice: Upgraded DAX to a completely new audio transfer architecture.

Starting with SmartSDR v4.2.18, the DAX functionality has been completely re-architected and is now called DAXv2.

This update delivers significant architectural improvements, enhanced low-latency performance, and improved compatibility and stability with modern Windows systems.

DAXv2 is available for all users.

In addition, DAXv2 is available as a native x64 and ARM application.

The new DAX driver no longer relies on deferred procedure calls (DPCs) for transferring audio data from the radio to PC applications.

For a complete listing of changes, refer to the HelpDesk article DAX Version 2 - Improvements and Updates.

Page 2 | Copyright 2026 FlexRadio, Inc. | SmartSDR v4.2.18 Release Notes | Important Notice: Updated CAT FlexVSP Driver.

Starting with SmartSDR v4.2.18, the FlexVSP driver, used to create virtual comm ports, has been upgraded to be fully compatible with both x64 and ARM versions of Windows 11.

As with DAXv2, this update is available for all users.

Important Notice: SmartSDR for Windows utilizes a Microsoft Installer (MSI)–based installation package.

Upgrading to an MSI installer architecture provides a standardized installation environment that can automatically detect and repair missing/corrupted components (“self-healing”) if files go missing.

It will install any needed .NET and system dependency software often without user interaction.

SmartSDR+ v4.2.18 New SmartSDR+ Early Access Features: As noted below, radios licensed for SmartSDR+ will gain access to these new features approximately 30 days after this Early Access release with a follow-up release of SmartSDR v4.2.

Feature Description Supported Radio Models

SMART-205

Band Plan/Band Edge Markers: SmartSDR now includes an integrated band plan display feature that provides a visual, color-coded representation of amateur radio frequency allocations based on IARU regional standards, including detailed sub- band information on the panadapter.

This feature gives operators a clear, at-a- glance understanding of ban​d usage recommendations directly within SmartSDR, helping ensure compliant and efficient operation across different international band plans.

Band plans for IARU Region 1, Region 2, and Region 3 can be selected from the panadapter display menu, providing an optional context-aware display based on the selected or active region, showing clearly defined sub-band segments within each amateur band.

The default IARU region is based on the radio’s region setting.

Aurora

FLEX-8000

FLEX-6000

SMART-11334

User Configurable RX Filters: SmartSDR now includes mode-specific, user configurable receive filters, allowing operators to tailor receiver bandwidth characteristics independently for each operating mode.

This enhancement provides greater flexibility and precision in tailoring audio and signal response for different types of operation, such as SSB, CW, AM, FM, and digital modes.

Additional benefits include reducing the need to manually reconfigure filters when changing modes and allowing users to fine-tune receive filter characteristics for contesting, DXing, or digital operation.

Aurora

FLEX-8000

FLEX-6000

SMART-12046

Display TX Filter on Panadapter: SmartSDR now includes an optional feature that displays the transmit filter bandwidth directly on the panadapter, with an additional on-screen overlay indicator.

This allows for real-time tracking of transmit filter bandwidth changes as mode or bandwidth settings are adjusted.

From an operational standpoint, this feature provides immediate visual confirmation of transmit signal bandwidth, helping operators ensure transmitted energy remains within the ham bands, which is particularly useful when operating near band edges.

Aurora

FLEX-8000

FLEX-6000

Page 3 | Copyright 2026 FlexRadio, Inc. | SmartSDR v4.2.18 Release Notes | New SmartSDR Basic Features: The following features are available to all users regardless of the SmartSDR feature license version installed on the radio hardware. Feature Description Supported Radio Models

SMART-12134

TURF Changes: New 60m allocation for the US. A new US TURF file is not needed to utilize the new 60m frequency allocation. Aurora

FLEX-8000

FLEX-6000

SMART-11748

• New ARM processor support for SmartSDR for Windows, SmartSDR, CAT, DAX, and
• FlexVSP drivers
• Aurora

FLEX-8000

FLEX-6000

SMART-11323

Added support for an external sampler for use with SmartSignal (aka “APD”) when operating with external amplifiers.

This enhancement enables the radio to use a real-time RF sample from the amplifier output, allowing it to measure and correct distortion introduced after amplification.

The result is improved linearity and cleaner signal performance, particularly at higher power levels.

Aurora

FLEX-8000

SMART-12206

Added APD Reset Button - This will clear the current solution and look for another Aurora

FLEX-8000

SMART-12223

Added new Waveform Deployments. You can now utilize our open API and Docker container to deploy waveforms on your radio. Aurora

FLEX-8000

• Page 4 | Copyright 2026 FlexRadio, Inc. | SmartSDR v4.2.18 Release Notes |
• SmartSDR Bug Fix Highlights:
• Below are the bug fixes highlights for SmartSDR v4.2.18. Some bug fixes may be specific to radio hardware platforms and
• SmartSDR+ feature license holders.
• Please refer to the SmartSDR v4 Changelog for a complete l