One of the things that intrigued me about my new Elecraft KX3 is that it has a built-in serial interface (the ACC1 port). I thought it might be a fun project to see if I could interface it with my Google Nexus 7 Android tablet via bluetooth, reminiscent of my old GOLog project with the Serial Sender. I couldn’t find much in the way of Android apps that would interface to the KX3 in a useful way, but I decided to put together a bluetooth-serial interface and then see if I could write an app of my own that might be handy for, say, SOTA activations and Field Day.

Although I haven’t gotten anywhere yet with writing my own Android app, I did come up with a bluetooth serial interface that works with the KX3. The detailed project description is here. A PC board is available from FAR Circuits, and the project is designed to fit nicely into an enclosure with a built-in 9V battery compartment.

My bluetooth-serial interface
My bluetooth-serial interface

The interface is designed so that you can use a straight-through stereo audio cable (like this one) to connect the interface to the KX3. If you build the interface intending to use it with the KX3, remember that the default baud rate for the KX3 serial port is 38400 baud, so you’ll either need to program the interface for that baud rate, or change the default baud rate of the KX3 to 9600 baud (the default for the bluetooth interface.

So far I’ve only found one Android app that will drive the KX3 via bluetooth, and that’s Hamlog from Pignology. I know that another Android app called KX3 Companion was recently released, but as far as I can tell, there’s no bluetooth support yet. The interface won’t work with any Apple devices thanks to Apple only allowing connection to approved devices.

I still have the goal of developing a field contest logging app for myself, and once it’s done you’ll see it here on my website.

5 thoughts on “Bluetooth for the KX3

  1. Am using your FB info for education. Don’t have a KX3. Do have a K3 (& K2).

    Was into S/W years ago. Need to update..!!

    • I’m actually thinking about updating the Serial Sender project so it uses BT, too. I need to write some Android software to make use of this first, though.

  2. Wonder if you could digitized the I/Q out to the tablet over bluetooth as well and have a nice waterfall and control of the radio. That would be pretty neat.

    • Sounds like an interesting project for someone who’s a lot smarter than me! Seriously, I don’t have any need for a panadapter, so someone else will have to tackle this one.


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