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K4 High Performance Direct Sampling SDR Software

 Current K4 Production Software

K4 Production Software (Release 30)  June 14, 2022

K4 Production Software - General Information
  • K4 software updates are handled at the radio itself.  An ethernet connection is required to obtain new software. It is also possible to load (or re-load) software from a USB flash drive. For further information on that topic, please refer to the K4 Operating Manual.
  • The K4 provides new features via software.
    As a result, you should consider the Release Notes as an extension of the Owners Manual. Documentation for the new features will be found there and will not appear in the Owner’s Manual until the next manual revision is released.
Current K4 Production Software Release Notes



==================== RELEASE 30 ===================== ====================================================

June 14, 2022

* * * IMPORTANT NOTE * * *

THIS RELEASE INCLUDES CESSB AND THE NEW NARROW CW FILTERS. For full details, please refer to the notes for release 29. (RX DVR record/play is still being refined.)

CW QSK IMPROVED: Reduced audible QSK artifacts caused by nearby signals.

MINI-PAN FIX: Corrected a case where the mini-pan could not be displayed.

TOUCH CONTROLS: Improved reliability of LCD touch interface.

LOW-PASS FILTER/RECEIVER CONFLICTS: Corrected receive audio loss that could occur due to invalid antenna selections. 6 meters was the band most likely to be affected.


=================== RELEASE 30Beta2 ================


June 1, 2022

===== BUG FIXES =====

CW-REVERSE TEXT DECODE: This is now working correctly.

CW-REVERSE MINI-PAN: There is no longer any unusual pixellation in CW-R mode.

TOUCH PANEL: Touch panel controller functions improved to eliminate errors/lockups.

RX AUDIO OUTPUT: Further corrections now in place to eliminate loss of audio.

MSG RPT in CW mode no longer continues to flash when a message is interrupted with a paddle or key.

ALC/POWER/SWR meters should no longer show "stale" values.

PAN FREEZE feature now completed.

MINI-PAN doesn't flicker on/off at times when it is touched but is not available.


#FRZn; is now working properly

Added #FRZ; getter

Added #FRZ/; toggle

#FRZn changes now sent to clients

Added MI/; toggle command Added new LOG; command to copy logs to any installed USB flash drive


===================== RELEASE 30Beta1 ======================


May 16, 2022


ALL RTTY MARK/SPACE TONE PAIRS FULLY IMPLEMENTED: All 8 mark/space tone pairs (MENU:FSK Mark Tone) are now fully implemented, with the correct offsets and filter bandwidths, including MENU:FSK Dual-Tone RX Filter.

RTTY 75 BAUD and PSK63 IMPLEMENTED: You can now use both 45 and 75 baud RTTY (FSK mode), as well as PSK31 and PSK63 (PSK mode). To change the selection, tap MAIN RX > TEXT DECODE, then select the desired baud rate.

===== BUG FIXES =====

REFERENCE MODULE FIRMWARE LOAD: The REF module now loads correctly in all cases when updating firmware.

AUDIO DROPOUTS: Loss of audio, typically at power-up, has been corrected.



DARC; command added (clear DAP recording buffers)

DR$; command added (data rate, e.g. RTTY 45/75 and PSK31/63)

DW; command added (TX data bandwidth)

PP command GET handler added (per-band power)

BN^; next band stack command added

#DSM1 command fixed (LCD display mode, spectrum + waterfall)

Sending AutoRef menu values when changed via #AR; command

OV$; getter added (ADC/COR overflow)

#SPM; getter added (span adjust mode; always returns 0)

PC010; (power control) now correctly sets power to 10 watts

ME43; command (menu parameter get/set) now returns IP address

ES0; and ES1; getters added to get SSB and ESSB bandwidth without requiring a mode change

New toggle commands:

#DSM/; #WFH/; #MP/; #VFA/; #VFB/; #CUR$/; #PKM/;


==================== RELEASE 29 ===================


March 22, 2022

NOTE: The RX DVR feature (AF REC/AF PLAY) has been deferred until Release 31 in order to complete implementation and field testing.


ENHANCED SPEECH COMPRESSION & CESSB: Speech compression has been dramatically improved. Controlled Envelope Single Sideband (CESSB) has also been implemented. Together, these boost average talk power by up to 8 dB, with virtually no RF overshoot or in-band distortion. Any nonzero setting of CMP also engages CESSB. Compression also now applies to Extended Single Sideband (wide transmit bandwidths).

TX NOISE GATE: This feature is available in all voice modes. Set up using MENU:TX Noise Gate Threshold. Default is OFF. If a non-zero value is selected, mic audio will be suppressed during transmit when it is below the given threshold.

NEW NARROW CW FILTERS: We've added new CW filtering for the 50/100/150/200 Hz settings -- the highest-performance narrow filters we've ever offered. These filters have much steeper skirts, yet exhibit minimal ringing. They're enabled by default, but can be turned off using the RX CW IIR Filters menu entry. When they're off, the filters will be the same as they are now (FIR). These filters are centered on 50 Hz pitch increments, which means that the narrowest filter width (50 Hz) slightly favors 50 Hz increments of the sidetone PITCH setting. For example, if you were using a 530 Hz sidetone, consider using 500 or 550 Hz instead.

ALL-MODE SQUELCH: Main and sub receiver squelch can now be used in all modes. The settings are independent.

NOISE BLANKER QRM FILTERING: Noise blankers can be compromised by strong nearby signals. If you hear artifacts, use the NB LEVEL control to turn NB QRM filtering on, then retry different NB levels. NB filtering removes strong signals in the IF demodulation passband (typically 2 to 20 kHz from the VFO frequency) while having a minimal effect on blanking effectiveness. There are 3 NB filter settings:

NARROW: K4 bases NB filter on regular RX bandwidth (as low as 1 kHz)

WIDE: K4 applies a 5 kHz NB filter

NONE: pre-NB filtering off (BW ahead of NB ~24 kHz)

NOTE: The NARROW and WIDE settings may reduce effectiveness on some noise types, so use NONE when there's no QRM.

NEW AM DEMODULATOR: Our new AM demodulator provides excellent audio fidelity, with up to 5 kHz audio bandwidth and enhanced pre-demodulator filtering.


VFO CURSOR OFF-SCREEN ICONS: The panadapter now provides color-coded arrows (A=blue, B=green) that appear if the associated VFO frequency is off-screen. The arrow shows the off-screen direction. VFO COARSE TUNING RATES (PER-MODE): Added a new menu entry, VFO Coarse Tuning, that specifies which of four per-mode tuning rates is to be used when the KHZ switch function is selected. (This is equivalent to the K3's COARSE switch function.) For example, in SSB mode, the "KHZ" tuning rate options are 0.1, 0.5, 1.0, and 2.5 kHz. When the user-specified KHZ rate is selected, the VFO digit underline changes from white to gold. These selections also apply to the RIT control whenever RIT is *OFF* and MENU:RIT Knob Alt Function is set to VFO CRS. Tapping VFO digits to select a tuning rate overrides the KHZ tuning rate.

NEW TRANSMIT MONITOR LINE-OUT MODES: Menu entry "TX Monitor Level, Line Out" sets the level of the transmit monitor signal (sidetone or voice) at the LINE OUT analog jack as well as digital line out (USB-B jack). At the default setting ("=MON"), the LINE OUT TX monitor level reflects the setting of the regular XMTR-MON knob function. Rotating VFO A counter-clockwise from here will select "OFF" mode (no TX monitor line out signal). The other available settings (numeric) will scale the LINE OUT transmit monitor function upward, which is useful for some external devices such as audio recorders. (These values will also prevent K4 switch tones from being heard at LINE OUT.) Max TX monitor LINE OUT level is about 2 Vpp.

TX BAR GRAPH FLICKER ELIMINATED: Previously, the power and SWR bar graphs exhibited rapid cycling or flickering in voice modes.

VOX-OFF WARNING IN CW MODE: If you send CW with VOX turned off (and PTT/XMIT not asserted), you'll now get a warning about not putting out any RF. You may ignore the warning if you're simply testing the keyer, sidetones, etc.

STUCK-KEY WARNINGS: Individual warnings are provided for all "stuck-key" situations on power-up, including PTT, KEY IN, DOT, and DASH.

DIGITAL AUDIO PROCESSOR (DAP) VOLTAGE REPORTS: The DAP now correctly reports its various supply voltages and temperature. To see these, use Status/All Param.

AM/FM VOX DELAY CORRECTED: These modes now use the voice VOX delay setting.


(Refer to rev. C1 or later of the K4 Programmer's Reference)

NB COMMAND CHANGE: The NB command format has changed to NBnnmf, where nn is the NB level, m is 0/1 (off/on), and f is the pre-NB filter mode (0=NONE, 1=NARROW, 2=WIDE). See description of filter settings above.


AG/ AF gain toggle

BL AF balance

DA digital audio

DW data TX bandwidth (DATA & AFSK modes)

PB DVR playback

VT$ VFO tuning step

#CUR$ VFO Cursor Display Mode

#PKM/ toggle panadapter peak mode

#VFA/B added toggle commands

ME43 COMMAND FIXED: This now correctly returns the radio's IP address.


XT/ TOGGLE COMMAND FIXED: This command now correctly toggles XIT on/off.


  • See K4 Software Release Notes for complete revision history.


    K4 Production BETA Software Release Notes

    None at this time


    See K4 Beta Software Release Notes for revision updates.


    K4 Production BETA Software Installation Procedures


    To install the beta software, make sure you have an ethernet connection, then:

    1. Tap Fn, then hold UPDATE

    2. Use the pulldown menu at the top of the screen to select Beta Release (if you didn't have this selected already).

    3. Tap Check for Updates. This downloads the new code but does not do the installation. This gives you an opportunity to optionally tap "Release Notes" and read the notes first.

    4. When you're ready to do the installation, tap "Install".

    NOTE: If the status area shows error messages of any kind, try doing the install a second time. You may have had an older version of the update app itself, in which case a second install should complete the process.