Knowledgebase: Radios > AirWare
How To Update the AirWare in Your Spektrum Transmitter
Posted by Jeff Fryer, Last modified by Jeff Fryer on 11 November 2015 09:55 AM

How To Update the AirWare

in Your SpektrumTM Transmitter


Updating your Spektrum transmitter is very simple, and only takes a few steps!


  1. Download the file SPMTX.SAX by clicking the "Download" or “Update” button.
  2. Save or copy the file from the PC to the SD card. NOTE: Do not change the SPMTX.SAX filename or the file will not auto-load into the transmitter (Tx).
  3. Right-click on the SD icon and select “Eject.” This will ensure that the entire file has been correctly written to the card.
  4. Power up the Tx with the SD card installed.
  5. You should see the Spektrum logo on the main screen and a progress bar while the new software loads.
  6. When it completes, in System mode use NEXT several times until you see the Serial Number screen. The version number is displayed on the same screen.  Verify the new version number matches the expected version from the download.


If you do change the filename in step 2, you can perform a manual update to the code.


  1. In the System menu, scroll to the bottom option to enter the SD menus.
  2. In the Option field, select Firmware Update.
  3. Select the file with the name you desired. Note:  If you are using a Macintosh or other *nix-based computer, there may be a file with the same name but having a leading dot (period).  Do NOT use the file with the dot.  Instead, scroll further down the list to find the one without the dot and select it instead.
  4. Continue from step 4 above.


Note: All software files are unique to the serial number registered online and will only work with the matching transmitter. Using a SAX file created from a different account or serial number will fail.


Sound Updates


Most of the newer Spektrum radios also include voice capabilities.  You can download sound updates by following this link:


Instructions for sound updates are found there too.




The most-commonly reported problem is the update fails.  Please try again with a different SD card, with a fresh download.  The file must be named SPMTX.SAX and must be in the root folder of the SD card.  Some browsers will insert numbers in the name when you have downloaded the same name.  You must remove those extra digits.


The next complaint is that the radio will start reading the update, get most of the way done, restart and try again.   The usual cause of this is skipping the “Eject” step above.  Start over at step 2 (save/copy) again.


If that does not resolve the problem, we suggest using a different SD card, and/or formatting the card and starting again.  Sometimes a card will have a flaw that goes undetected until a file is written to it.  When formatting, don’t use the Quick option.  The SD card must be Class 6 or lower, and 32g or smaller, formatted to FAT or FAT32.  Name brands such as Toshiba and SanDisk provide the most compatibility.  NOTE:  SD cards usually come properly formatted!  If you wish to perform a low-level format on the card, we recommend using this:


If you are continuing to have problems, please contact the Product Support group at your nearest Horizon Hobby office for help in resolving it.

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