Elecraft KAT500 firmware

Firmware history

All versions below were published by Elecraft on elecraft.com. Third-party and modified firmware is never listed.

1. Version 2.16 Latest Released May 29, 2024 First seen Sep 6, 2026

   Fixes Kenwood memory channel IF response handler. — summary by updatemystuff.com

   Source: elecraft.com

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   Bugfix: Ke​nwood memory channel IF ​response handler.

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2. Version 2.15 Released Sep 26, 2023 First seen Sep 14, 2026

   Source: elecraft.com

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   Bugfix: Attenuator not d​eployed when it should have been during ATU tune. A​ggravated exciter foldback.

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3. Version 2.14 Released Sep 21, 2023 First seen Sep 14, 2026

   Source: elecraft.com

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   Bugfix: Serial port spee​d changes using BR command were not bein​g stored in EEPROM.

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4. Version 2.13 Released Sep 12, 2023 First seen Sep 14, 2026

   New ATU settings per bin feature limits stored settings per frequency segment; fixes band-change stutter. — summary by updatemystuff.com

   Source: elecraft.com

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   Add "ATU settings per bin" to limit the number of ATU settings that can be stored in any given "bin" (frequency segment) for a particular antenna.

   Each "bin" has room for ​6 ATU settings, shared by all three antenna connectors.

   For example, If you're using all 3 antenna connectors for a particular band, you might limit the maximum number of ATU settings for each antenna to 2.

   If you're using 2 connectors on another band, you might set ATU settings per bin to 3.

   See the updated KAT500 Automatic Antenna Tuner Serial Command Reference AB command for details.

   An updated KAT500 Utility may be used to configure ATU Settings per bin.

   Illuminate BYP LED in modes AUTO and MAN when the current ATU setting is "bypassed".

   DM command response trimmed, now shows the number of unused ATU settings on one line.

   Band, bin, and EEPROM address were removed.

   BYP relay shown only when bypassed.

   Added trailing ; CR LF.

   In some low forward power high SWR scenarios when only the frequency counter is used to detect band change, the ATU was reluctant to change ba​nds and full search tunes "stuttered".

   Full search tune requires more than minimum power to compute an accurate SWR, 20 watts is suggested.

   Use last-measured SWR bypass when capacitor or inductor is manually changed.

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5. Version 2.10 Released Jun 27, 2023 First seen Sep 14, 2026

   Source: elecraft.com

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   Add semicolon ​terminator to DM command response. Reset amp key interrupt when fault is cleared if no longer transmitting. Don't undo manual ​AMPI1; setter without power cycle.

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6. Version 2.08 Released May 11, 2022 First seen Sep 14, 2026

   Source: elecraft.com

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   Accept AKIP and SM com​mands with leading​ spaces and don't require leading zeros.

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7. Version 2.07 Released Jan 7, 2022 First seen Sep 14, 2026

   Source: elecraft.com

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   Some low power​ full search tunes were errone​ously replaced with "bypassed".

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8. Version 2.05 Released Oct 11, 2021 First seen Sep 14, 2026

   Adds support for multiple transceiver brands, improves frequency tracking, and realigns band boundaries. — summary by updatemystuff.com

   Source: elecraft.com

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   Accept K4 transceiver frequency messages with 1 kHz resolution via AUXBUS Accept IF, FA, FB, and FT transceiver TX frequency messages from Elecraft K3S, K3, KX3, Kenwood, Flex, Yaesu FT-450, FTDX3000, FTDX5000, FT-891, FT-991A, FTDX101MP, and FTDX101D.

   KPA500 and some logging programs poll with these messages.

   Add commands: FC; (TX frequency count), FX; (last XCVR or CAT-supplied frequency), and FY; ​that shows the frequency span for the currently selected ATU memory.

   An updated KAT500 Utility Program shows these values on the Operate tab.

   Add FDT; command to specify the distance, in kHz, between the current ATU frequency and a new TX frequency count for the ATU to retune.

   DM; command, without a specified frequency, shows all the stored ATU settings for the currently selected frequency segment (bin) Add FTNS; command to perform full search tune, but skip saving the result.

   ATU settings can then be saved with SM; if desired.

   Commands FCCS, FCMD, MTA, and MTM are removed or have no effect.

   See the updated KAT500 Automatic A​ntenna Tuner Serial Command Reference for details on new commands FC, FX, FY, FDT, and FTNS.

   Revise frequency counter to better track SSB TX count changes Favor frequencies supplied by command or transceiver over the frequency counter Align bins to band boundaries.

   The first 80 meter bin is now 3500-3509 kHz rather than 3481-3500.

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9. Version 1.79 Released Sep 2, 2018 First seen Sep 14, 2026

   Added SWR protection to interrupt amplifier key line when threshold exceeded in all modes. — summary by updatemystuff.com

   Source: elecraft.com

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   Interrupt ampli​fier key line when SWR exceeds a configurable threshold in all ATU modes, including Bypass. SWR Threshold for amplifier key interrupt may be configured high (99:1) to disable this protection mecha​nism. See KAT500 Utility Help: Configuration, Edit Configuration, SWR Thresholds.

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10. Version 1.75 Released Apr 26, 2016 First seen Sep 14, 2026

    Frequency counter updates immediately from F, FA, or MT commands to prevent incorrect ATU settings. — summary by updatemystuff.com

    Source: elecraft.com

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    When ATU's frequency is set with F, FA, or MT commands, update TX fre​quency counter from the command rather than waiting for next transmission. Avoids switching​ to the ATU settings for the old TX count frequency on next TX before the TX frequency is counted.

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11. Version 1.71 Released Feb 26, 2015 First seen Sep 14, 2026

    New FCCS command controls frequency counter responsiveness; fixes band switch retuning. — summary by updatemystuff.com

    Source: elecraft.com

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    When Memory Recall Tune in Manual and Auto are off, don't ret​une on band switch frequency count.

    Add FCCS (Frequency Count Continuous Sample time) command to influence frequency counter inertia.

    Lower values cause the KAT500 to more quickly accept a new frequency count, higher values make the KAT500 less willing to move.

    This is likely to make the most difference in SSB. (FCCS was​ removed in 2.01) Use KAT500 command tester: FCCS; to query.

    FCCS nn; to set.

    Default is 12 msec.

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12. Version 1.67 Released Mar 12, 2014 First seen Sep 14, 2026

    Tuner finds better solutions by resisting transient SWR dips; Icom AH-4 behavior improved — summary by updatemystuff.com

    Source: elecraft.com

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    Attempt to avoid early search termination by a transient SWR dip.

    Pause for excit​er fold back recovery and average over more coupler samples when tuner setting is "best so far" or reaches "stop tune" threshold.

    Tuning speed changes a bit, but sometimes a better tu​ning solution is found.

    Change Icom AH-4 Start to avoid full search tune on each Icom TUNE button press

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13. Version 1.65 Released Mar 7, 2014 First seen Sep 14, 2026

    Source: elecraft.com

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    Perform memory recall tune on transiti​on from mode BYP to MAN or AUTO Bug fix: was releasing ICOM AH-4 k​ey line too early Speed up some tunes

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14. Version 1.63 Released Feb 24, 2014 First seen Sep 14, 2026

    Source: elecraft.com

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    Additional filtering of c​oupler ADC counts Reduce tim​e-to-sleep after each transmission

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15. Version 1.58 Released Feb 12, 2014 First seen Sep 14, 2026

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    Don't interrupt amplifier key on h​igh SWR unless forward power exceeds about 25 ​watts Don't use attenuator when forward power is very low

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16. Version 1.57 Released Feb 10, 2014 First seen Sep 14, 2026

    Source: elecraft.com

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    Use K3 VFO frequency,​ if available, to determine mem​ory address to store tune solution

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17. Version 1.56 Released Feb 9, 2014 First seen Sep 14, 2026

    Source: elecraft.com

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    Ignore band line chan​ges and AUXBUS frequency messages whi​le transmitting

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18. Version 1.55 Released Feb 7, 2014 First seen Sep 14, 2026

    Enables memory recall tuning via VFO tracking and adds antenna control command. — summary by updatemystuff.com

    Source: elecraft.com

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    Perform VFO tracking Memory Recall Tunes using K3 frequency, without requiring transmiss​ion.

    Requires K3 firmware revision 04.82 or later, with K3 CONFIG: KAT3 menu option KAT500Y enabled (tap numeric keypad 1 to toggle) and Memory Recall Tune on QSY enabled in KAT500 Edit Configuration, and band line and AUXBUS ​lines connected (e.g.

    KPAK3AUX or E850463 cables).

    Add AN0; command to advance to next enabled antenna

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19. Version 1.54 Released Feb 3, 2014 First seen Sep 14, 2026

    Reduced SWR threshold to 3:1, improved frequency counter stability, added High SWR fault and Cancel Tune command — summary by updatemystuff.com

    Source: elecraft.com

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    Improve Tx frequency counter stability Reduc​e default amplifier key interrupt SWR threshold from 99 to 3:1 Add a new unlogged "High SWR" fault when SWR exceeds amplifier key interrupt SWR thresh​old; reset by transmission with lower SWR Add "CT;" Cancel Tune command

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20. Version 1.42 Released Dec 11, 2013 First seen Sep 14, 2026

    Source: elecraft.com

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    Invoke a finer granularity ​Full Search Tune if tune is repeated within 5 seconds Add "TP;" qu​ery to query tuning status Keep LEDs on while sleeping

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21. Version 1.41 Released May 29, 2013 First seen Sep 14, 2026

    Oscillator can turn off when idle to eliminate unwanted signal; adds Auto Fine Tune and startup power control. — summary by updatemystuff.com

    Source: elecraft.com

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    Use KAT500 Utility 1.13.4.2 or later for this firmware version.

    KAT500 firmware can now be configured to turn off its crystal oscillator when logically powered off or when "idle".

    This removes a signal at about 28004.5 kHz.

    See KAT500 Utility Configuration tab, Edit Configura​tion, Idle Sleep.

    This microcontroller "Idle Sleep" capability is initially disabled because some computer programs may require change to add serial port polls to "wake up" the KAT500 before sending commands.

    See the updated KAT500 Serial Command Programming Reference, SL command, for details.

    Add command to control whether KAT500 starts up with power off (PSI0;) or power on (PSI1;) when DC power is initially applied.

    See KAT500 Utility Configuration tab, Edit Configuration, Initial Power.

    Add "Auto Fine Tune" (AFT) command to use smaller​ inductance steps during coarse search tune.

    Full search tunes take slightly longer, but are sometimes able to find more matches for high SWR antennas with narrow ranges, particularly on the low bands.

    See KAT500 Utility Configuration tab, Edit Configuration, Auto Fine Tune.

    Alternatively, tap TUNE again within 5 seconds if a match is not found.

    Add FA command to initiate Memory Recall Tune Reduce minimum power required for Memory Recall Tune

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22. Version 1.32 Released Feb 22, 2013 First seen Sep 14, 2026

    Memory Recall Tune auto-recalls settings when switching frequencies in same band; improved tuning. — summary by updatemystuff.com

    Source: elecraft.com

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    Add Memory Recall Tune for in-band QSY.

    When the KAT500 detects drive on a frequency within the same band, but in a different band segment, it will recall settings previously stored for that segment.

    This feature defaults ON in mode MAN and mode AUTO, but may be disabled via the KAT500 Utility.

    Select Configuration, Edit Configuration, Tune on QSY.

    KAT500 Utility version 1.13.2.13 or later is required to access thi​s menu.

    Perform Memory Recall Tune on in-band QSY on Tx frequency count in Mode MAN, without regard to SWR.

    Perform Memory Recall Tune on in-band QSY on Tx frequency count in Mode AUTO, without regard to VSWR, followed by a Full Search Tune if needed.

    Add MTA and MTM commands to permit owner to enable or disable Memory Recall Tune on in-band QSY.

    See KAT500 serial command reference.

    KAT500 Utility configuration support for this command is in KAT500 Utility version 1.13.2.13 and later, Configuration Tab, Edit Configuration, Tune on QSY.

    Reduce minimum "start tune" power from 7 watts.

    Reduce Full Search Tune time when starting on a nearby frequency.

    Clear fault on all button presses, antenna change, band change.

    Fault when transmit power exceeds 100W with amplifier key line interrupted Add optional frequency to SM command to permit saving tuner settings without having to transmit on​ that frequency.

    See new KAT500 Serial Command Reference for detailed syntax.

    Add FLTC; serial command to clear current fault Issue FT; response when tune completes and exciter tune power is no longer needed.

    Add PS; and PS1; serial commands to query and turn on power.

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23. Version 1.18 Released Dec 3, 2012 First seen Sep 14, 2026

    Reduced minimum start tune power to 7.5 watts and accelerated coarse tuning steps. — summary by updatemystuff.com

    Source: elecraft.com

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    Reduce minimum "st​art tune" power from 10 to 7.5 watts.

    Some ICOM radios produce just under 10 watts when their TUNE button is pressed.

    Matches will sometimes improve if higher power (20 watts) is used.

    Use "bypassed" ​if Bypass SWR is better than full search tune result SWR.

    Speed up coarse tuning steps.

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24. Version 1.13 Released Nov 6, 2012 First seen Sep 14, 2026

    Source: elecraft.com

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    Display last-known SWR in KAT500 Utility after​ transmission stops Alter the criter​ia for rejecting frequency counts introduced by nearby transmitters

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25. Version 1.10 Released Nov 4, 2012 First seen Sep 14, 2026

    Attenuator deployment now conditional on power level and SWR recovery delay added. — summary by updatemystuff.com

    Source: elecraft.com

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    Deploy the attenuator on​ each full tune unless power is too high. Disconnect attenuator if we don't have enough VFWD. Add a short delay after tuning but before releasing the amplifier key interrupt relay to g​ive the amplifier a little time to forget SWR during tuning

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26. Version 1.05 Released Oct 31, 2012 First seen Sep 14, 2026

    Added Amplifier Key Interrupt Power control and improved auto tune behavior — summary by updatemystuff.com

    Source: elecraft.com

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    Reduce tendency to repeatedly auto tune on the same frequency when near the auto tune threshold Change handling of the configuration option "Amplifier Key Interrupt SWR Threshold"​.

    This per-band threshold can be set to 99:1 or larger to defeat this function; it was hot switching some amplifier keying relays unnecessarily.

    KPA500 owners may wish to reduce the Amplifier Key Interrupt SWR threshold to a level that inhibits KPA500 high SWR faults.

    Use the KAT500 Utility Configuration tab, Edit Configuration, VSWR Thresholds, to set this value.

    The default for this threshold is 99:1.

    The "Amplifier Key Interrupt SWR Threshold" is not tested in mode BYPASS.

    Significant changes in how the amplifier key line interrupt relay is handled.

    This was done for amplifiers other than the KPA500 that might be damaged by interrupting the amplifier's T/R relay while RF is present.

    The default value is chosen to be safe for any amplifier.

    Add a new "Amplifier Key Interrupt Power" (AKIP) threshold to allow per-owner control of the KAT500's use of the the amplifier key line interrupt relay.

    The value you choose depends on your amplifier's ability to hot switch its T/R keying relay.

    Some amplifiers (e.g., KPA500) have solid-state switches and are designed to switch the T/R relay at full power.

    For these amplifiers, an "unlimited" threshold is appropriate. 1500 watts is interp​reted as "unlimited", even if the amplifier is incapable of 1500 watts.

    KPA500 owners should choose 1500.

    Some amplifiers have relays that should not be switched at high power.

    Set the threshold to a value that is safe for your amplifier.

    The factory default for is 30 watts.

    Use the KAT500 Utility version 1.12.11.8 or later, Configuration tab, Edit Configuration, Amplifier Key Interrupt Power.

    Click Help from this dialog for recommended settings.

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27. Version 1.04 Released Oct 21, 2012 First seen Sep 14, 2026

    Source: elecraft.com

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    If ring of J3B is held low durin​g startup, ignore it thereafter to prevent continuous tuning. Cycle DC power to recheck. Can​cel full search tune by tapping MODE, ANT, or TUNE button

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28. Version 1.00 Released Oct 9, 2012 First seen Sep 14, 2026

    Source: elecraft.com

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    First production firmware version

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