KX3 Software Page

KX3 Beta Firmware Revision

MCU 1.94 / DSP 1.28, 3-8-2014

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


  • * 8.5-9.5 MHz TRANSMIT AND ATU OPERATION IMPROVED: Corrected low power output in this range, which also allows the ATU to function normally. Note: Applies only if the KX3 is enabled for transmit in this range (U.S. “MARS” allocations, etc.).
  • * KXPA100 POWER SETTING IMPROVEMENT: The KX3’s PWR control can now be adjusted across the 10-watt/11-watt boundary in either direction during transmit (including TUNE mode) without causing a large spike in KXPA100 power output. Also, during TUNE, the “TX” knob function is now always assigned to power output rather than keyer speed or mic gain.
  • * AGC-OFF AF LIMITER NOW WORKING: Some operators prefer to turn off AGC and control gain manually using the KX3’s RF GAIN control. However, if an extremely strong signal is present with AGC off, audio output can be uncomfortably loud. The KX3 provides an AF limiter for the AGC-off case. Use the AF LIM menu entry to adjust the threshold at which limiting takes place.

      For Application Programmers:

  • * "PO" (POWER OUTPUT READ) COMMAND NOW USABLE IN QRO MODE (KXPA100 ENABLED): As with the KX3’s bar graph, the “PO” command returns an estimate of KXPA100 power output based on KX3 drive level. You can use the KXPA100’s “^PF” command to read the amp’s power output more accurately.
  • * "OM" COMMAND NOW SHOWS KXAT100 AND KX3-2M OPTIONS: These are represented by the letters ‘T’ and ‘X’ respectively in the “OM” response. Refer to the K3/KX3 Programmer’s Reference.
  • * ATU.X MD MENU ENTRY (KXAT100 MODE) NOW ACCESSIBLE: When the PA MODE menu entry is set to ON, the ATU MD menu entry changes to ATU.X MD to show the mode of the KXAT100 external ATU. The “MP” command can now be used to read (but not set) the KXAT100’s mode in this case. (To change the mode, use the KXPA100’s ^MP command.)

KX3 Production Firmware Revision

MCU 1.87 / DSP 1.28, 11-26-2013

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

  • WITH KXPA100 IN, LOW SUPPLY VOLTAGE DOES NOT DROP KX3 TO 5 W: If the KXPA100 is connected via the special control cable, and PA MODE = ON, the KX3 will not drop out of QRO mode and go to 5 W at 11 V, as it does without the amp present. This allows the KX3+amp to be used with somewhat depleted 12-V batteries. The operator should monitor key-down battery voltage (e.g., by using the KX3’s “DISP” function) and reduce target power output if necessary. For example, if the key-down voltage is ~11 V, target power should be set no higher than 40-50 W. If it’s ~10 V, battery life should be conserved by using the KX3 at QRP levels. (To minimize current drain in this case, set PA MODE to OFF.) Some 12-V batteries, such as gel-cells, can be permanently damaged if discharged below about 10.5 V.

  • TX GAIN MENU ENTRY FIXED: Wasn’t always displaying per-band drive power accurately in QRO mode (i.e., with PA MODE = ON).

  • AM BROADCAST BAND (BCB) RECEIVE OPTIMIZATION: If you have a KXAT3 ATU installed, you can select one of two optimizations for reception below 1300 kHz. While in the ATU MD menu entry, tap ‘1’ (PRE) to select either BCB NOR (the original setting, which reduces the amplitude of received harmonic images), or BCB=160 (a new setting that may improve receive sensitivity by using the 160 meter ATU settings even below 1300 kHz). BCB NOR is recommended unless you need BCB=160 in order to copy a weak AM station. You can also improve sensitivity by using higher preamp gain settings (use the PREAMP menu entry, which is per-band).

  • SUPPORT FOR HEIL HC-6 MIC ELEMENTS: Mic gain can now be set as much as 20 dB higher to support these low-sensitivity elements. NOTE: USE LOW “MON” (VOICE MONITOR) LEVEL IF MIC GAIN IS SET ABOVE 50. Otherwise you may hear acoustic feedback. Also, higher gain settings in general can make any transceiver more susceptible to noise pickup. If this is a problem, consider using a more conventional mic element that has greater output. The Elecraft MH3 has excellent frequency response, comparable to earlier Heil elements, yet it has far higher output than the HC-6.

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

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