[Elecraft] New K4 & K4/0 Beta releases: Spectral Subtraction Noise Reduction and other features

[Dave Sublette]

Speaking of back porting to the KX3, what about the K3?  Any hope that this
might end up on the K3 also?

K4TO

On Mon, May 11, 2026 at 3:37 PM Wayne Burdick via Elecraft <
elecraft at mailman.qth.net> wrote:

> The latest beta release for the K4 and K4/0 software includes the
> long-awaited Spectral Subtraction Noise Reduction feature (SSNR). Our Field
> Testers have found our SSNR algorithm to work very well in all modes,
> especially SSB and CW, with many commenting it's the best NR they've used.
>
> We've also implemented a new STARTUP macro capability. This allow users to
> customize the K4's power-up behavior. For example, you can have SPLIT
> always default to OFF if desired.
>
> This beta release is recommended for all K4 users. Please test using all
> bands, modes, and features you normally use, while also giving SSNR a good
> workout. For full details see release notes below.
>
> IMPORTANT: If you have both a K4 (or K4D) and K4/0, you'll need to install
> new software on both. This is necessary to coordinate access to new
> features between the two units.
>
> 73,
> Wayne
> N6KR
>
>
> ===========================================================
> ====================== K4 R38.BETA3  ======================
> ====================== K4/0 R3.BETA1 ======================
> ===========================================================
>
> May 11, 2026
>
> ------------
> NEW FEATURES
> ------------
>
> - ADDED SPECTRAL SUBTRACTION NOISE REDUCTION (SSNR): SSNR is a major
> enhancement to the K4's receivers, often suppressing background noise to
> nearly inaudible levels. In addition to making reception more pleasant,
> SSNR can often clarify signals near the noise floor that were highly
> degraded. SSNR works in all modes but is especially effect on speech
> signals.
>
> TO USE SSNR: Hold the NR LEVEL switch, change the algorithm from "LMS"
> (least mean squares, the original NR algorithm) to "SSNR", and select a
> level from 1-20. Higher level values will suppress noise to a greater
> degree, at the expense of some erosion of weak signals. As with all NR
> algorithms, the lowest effective value should be used.
>
> NOTE: In CW mode where weak or tightly packed signals are present, LMS NR
> may be preferred. Also, CW copy may be better enhanced by narrowing filter
> bandwidths or using APF rather than using NR. Filtering and APF can also be
> combined with NR and NB for maximum benefit.
>
> - RIT/XIT OFFSET KNOB SPEED REDUCED: The RIT/XIT offset knob's steps per
> turn rate is now set to 50 when VFO A is set for 100, and 100 if VFO A is
> set for 200 or 400. This makes fine-tuning of signals easier.
>
> - CLIENT FREQUENCY MEMORIES: The K4/0 (and K4 when used as a remote client)
> store their own set of GP and Quick memories internally. Those memories now
> apply to every server K4 to which the client connects. Any changes remain
> local to the client. Client activity never changes memories stored on the
> server. If two clients connect concurrently to the same server, they will
> each have their own set of GP and Quick memories. NOTE: When you first
> install this update, your *most recent* per-Server Quick Memories will be
> saved. Any memories that you save from now on will apply to ALL servers. As
> a one-time side effect, GP memories may be replaced by factory defaults,
> mostly blank except for 60 m presets.
>
> - NOW PRESERVING STATES OF SPLIT, TEST, VFO LINK, AND VFO LOCK: The new
> STARTUP macro (see below) allows full customization of the K4's power-up
> state, so we no longer automatically turn these settings off.
>
> - STARTUP MACRO: You can now automatically set up initial conditions each
> time the K4 is turned on, if desired, by editing the STARTUP MACRO. Tap Fn,
> then select MACROS. Scroll to STARTUP (at the top of the list). To bring up
> a text keyboard, tap the empty field at the right end of this selected line
> on the screen. You can bypass execution of the startup macro by holding the
> REV switch during power-on.
>
> For example, if you want SPLIT to be turned OFF on power-up, enter the
> command "ft0;" as the macro command. (A semicolon is required at the end of
> each command in the list.) Another typical use of the startup macro is to
> jump to a preferred frequency and/or mode. The command "fa14250;md2;" in
> the STARTUP macro would set the K4 to 14.250.000, USB mode. Refer to the K4
> Programmer's Reference for full details on available control commands.
>
> ---------
> BUG FIXES
> ---------
>
> - ANT and RX ANT button configuration tracks server ANT CFG correctly upon
> connection.  Changes made to ANT CFG while connected do not modify the ANT
> CFG of the Server, only the Client, and only temporarily for the duration
> of the connection. (Host commands RS2, ACM and ACT may be used to change
> Server ANT CFG while remote, if required.)
>
> - DVR message play can now be interrupted via PTT or VOX activation. RF
> switching artifacts eliminated from DVR message play.
>
> - Eliminated ALC/CMP metering glitch at start of remote transmission. Also
> eliminated false triggering of VOX.
>
> - TX Inhibit status on client now passed correctly.
>
> - RX EQ adjustments on client now adjusting server properly.
>
> - REV button now functions correctly when activated from a K4/0.
>
> - RX command now clears client streaming DVR message.
>
> - Internal storage for frequency memories now based on Client (K4/0) serial
> number.
>
> --------------
> FOR DEVELOPERS
> --------------
>
> - DARS (start voice recording of speaker audio) is now allowed in the
> STARTUP macro.
>
> - Updated RS (Remote Set) command:
>
>   * Added '2' as a new parameter for experimental mode command tunnel.
>     RS2; enables a remote set command tunnel which, when enabled,
>     causes commands to be forwarded to the server radio.
>     For example, RS2;MG0;RS0; will set MIC GAIN on the server radio to 0
>     without affecting the client radio.
>
> - Added NRS command for SSNR configuration. Associated change to NR command
> (for LMS).
>
> - RX; command interrupts DVR messages sent to server.
>
> - RX; command interrupts KZ commands in progress on server.
>
> - TXPARAMS in status area no longer flickers between 0 and current value.
>
> --
> Elecraft, Inc.
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