KX3 Software Page

KX3 Beta Firmware Revision


Please read KX3 Beta Firmware Instructions for installing beta firmware.
Only the current production firmware releases can be downloaded by KX3 Utility automatically.


KX3 Production Firmware Revision

MCU 2.76 / DSP 1.50, 4-27-2017

See KX3 Firmware Release Notes for a complete revision history.
This release can be automatically downloaded by KX3 Utility

  • FINER STEPS FOR AF GAIN AND MONITOR LEVEL: Both the monitor level (MON) and AF gain control now provide somewhat smaller increments.

  • AF GAIN LEVEL RESTORED: An earlier firmware release unintentionally reduced the KX3’s maximum AF gain.

  • ATU DATA SETS FOR USE AT DIFFERENT LOCATIONS: The KX3 will now store two full sets of per-band data for the internal ATU (KXAT3). Use the ATU DATA menu entry to select which set to use. Typically SET 1 is used at a home location, and SET 2 for field operation. Note: This has no effect on KXAT100 ATU data, which is stored separately for each of the KXPA100 amplifier’s antenna jacks.

  • ATU LC NETWORK VALUE DISPLAY: In either the ATU.DATA or ATU MD menu entry, tapping the "ATU" switch shows the present values of L (inductance), C (capacitance) and N (L-network configuration). This applies only to the internal ATU (KXAT3). The displayed data format is LxxCxxNy. is a 2-digit hexadecimal value that, when converted to binary, shows which ATU L or C relays are engaged. shows which side of the L-network the capacitance is on: Nt = TX side, and NA = antenna side.

  • ATU CLEAR AFFECTS ONLY CURRENT DATA SET: Within the ATU DATA or ATU MD menu entries, CLR (hold of the OFS/B knob) now clears KXAT3 ATU data only for the presently selected data set (SET 1 or SET 2) on the present band. As before, CLR is recommended when using the internal ATU with a new antenna. Once the data is cleared, very few ATU tune operations will usually be needed to cover an entire band. Note: If a KXPA100 amplifier is connected, the CLR operation applies to the KXAT100 ATU’s per-band/per-antenna data, not to the data for the internal KXAT3 ATU.

  • PX3 UPDATED WITH CORRECT PREAMP DATA: When the MENU:PREAMP setting is changed, we now update the PX3.

  • PSK-D/FSK-D SIDETONE HANG FIXED: Corrected a problem where sending characters at very slow speeds or with paddles continuously pressed could cause a transmit timeout, leaving the sidetone on.

  • SCANNING WORKS WITH FREQUENCIES BELOW 1.0 MHz. Previously, scanning would stall in this case.

  • DT, FR, and FT HOST COMMANDS DISALLOWED IN TX MODE: Previously, these commands (data submode, unsplit, and split) could be sent to the K3 during transmit from software applications. This could sometimes cause side effects such as muting of transmit audio in DATA modes.


  • POWER OUT NOW 15 WATTS MAX, 80-20 M: On 80-20 meters, the PWR control can now be set as high as 15 W (max is still 12 W on other bands). Supply voltage must be over 12.8 V on key-down as indicated by the KX3’s voltage display (tap DISP, rotate VFO B). Note: The KX3 will automatically reduce power as required if current, SWR, or temperature is excessive, or if supply voltage is too low. If a band other than 80-20 m is selected, power output will be cut back to 12 W max. It must then be manually set above 12 W after switching to 80-20 m.

  • PSK63 MODE ADDED: Tap DATA, rotate VFO B until PSK D is displayed, then use VFO A to select 31 or 63 baud. The default is PSK31.

  • 4-METER POWER OUTPUT IMPROVED: Changed IF band-pass filter configuration to increase drive level on 4 meters. This should improve 4-meter power output in cases where it was marginal due to filter rolloff.

  • 10 W OUTPUT DOWN TO 10-V SUPPLY: The KX3 can now put out up to 10 W from a supply voltage as low as 10 V on key-down, assuming that other parameters remain within range (current, temperature, and SWR). This will allow the use of up to 10 W for much longer when running from an 11-V battery, such as a 3-cell Li-ion pack. While we still recommend the use of 11 V or higher when using 10 watts output, this change will allow you to get a few extra dB in the field when you really need it. NOTE: Transmit IMD performance is better at higher voltages. When running from a 10-11 V battery, only use max power (10 W) when absolutely necessary. Home stations should use a 13-14 V power supply when running full power.
  • 2 METER/4 METER TX CURRENT LIMIT INCREASED: Transmit current can now be somewhat higher when using the internal 2-m or 4-m module. Previously, some units were not able to attain full power output.
  • EXPERIMENTAL CW QSK MODE: Tapping ‘3’ (APF) in the CW WGHT menu entry selects either OLD QSK (original) or NEW QSK (which purges the DSP’s audio pipeline on every key-down). NEW QSK reduces audio artifacts heard in the receiver during CW keying on a noisy band, at the expense of a slightly longer receive-recovery time. (We hope to speed up RX recovery in a future release.) To verify the benefit of NEW QSK: First select a CW RX filter bandwidth of 400-1000 Hz, then transmit 20 WPM dits (at 0.0 watts) on top of an S5 or stronger carrier, or in the presence of S7 or stronger atmospheric noise. While transmitting, you can be in the CW WGHT menu entry, alternating between OLD and NEW QSK by tapping ‘3’ (APF).
  • 60-M U.S. BAND LIMITS CORRECTED: CW/DATA, TUNE, and ATU TUNE are now usable on all 5 channels. Previously, BND END was displayed in some cases. Note: This also applies to other countries where the U.S. band limits are used.
  • RX EQ NO LONGER APPLIED IN DATA MODES: Previously, the RX EQ settings for voice modes were being applied to data modes.
  • KX3 CHANNEL HOPPING UPDATES PX3 DISPLAY PER-MODE: When channel hopping is used (by tuning the VFO or scanning), the PX3 display is now updated based on the mode of each “channel” (frequency memory) in the hop range. This is especially useful on 60 m, which includes both CW/DATA and SSB allocations. See page 17 of the owner’s manual for scanning/channel-hopping setup instructions.


KX3 Archived Firmware Revisions

Please browse our KX3 Firmware Archive FTP Folder for obtaining archived KX3 firmware revisions.
Only the current production firmware releases can be downloaded by KX3 Utility automatically.


KX3 Utility and Drivers for Windows, Mac and Linux


Minimum Operating System Requirements for Elecraft Utilities:

Microsoft Windows: XP Service Pack 3 or later, including Vista, 7, 8, and 8.1.

Apple Mac: OS X 10.6 (Snow Leopard) or later

X86-based Linux: GTK+ 2.8 or later, glibc-2.4, libstdc++.so.6 and cURL. 64-bit Linux requires 32-bit compatibility libraries.


Elecraft KXUSB Cable for the KX3

Elecraft offers the KXUSB cable for USB only computers etc.  It uses the FTDI chip set.

Before plugging in this cable to any of your computer's USB ports, you may need to install the correct FTDI USB drivers for your computer's operating system.   Drivers are available for most Windows, Mac, and Linux OS's.  Note that most of the latest Windows 7 operating systems already have the proper drivers for the FTDI chip set and will automatically install them if you just plug the KXUSB cable into a USB port.

Connecting the KX3 to a Computer

If your computer has a standard serial port, all you will need is our KXSER cable for the KX3. .

Most modern computers no longer have serial ports but instead use USB (Universal Serial Bus) ports for connecting to external devices. Elecraft provides the KXUSB cable to connect the KX3 to these computers.

KX3 Utility Download


KX3 Tools and Application Notes