Did I mention that I just received my new Elecraft KX3 (#5522) ham transceiver? Wonderful rig (but more on that in another post). The KX3 ships with your choice of a USB cable or a serial cable for interfacing with your PC. With either of these cables, you can use Elecraft’s KX3 Utility software to update the KX3’s firmware, or you can otherwise control the rig with suitable software (say, Ham Radio Deluxe) running on your PC. At any rate, I received the USB cable with my KX3.

I’m interested to see if I can rig up a bluetooth connection between my KX3 and my Android tablet, though, and it seemed that a good place to start would be to fabricate a serial cable, to which I could ultimately connect a serial-to-bluetooth adapter of some sort. Here’s how I did it.

The KX3’s ACC1 port is where you connect a three-conductor 3.5 mm audio plug for serial communications. On the PC side, you need a DB9 female connector to plug into your PC. Connect them like this:


DB9F Connector Connects to 3.5 mm Audio Plug
pin 2 (TX to PC) ring
pin 3 (RX from PC) tip
pin 5 (ground) sleeve

This is the standard scheme for connecting the KX3 to a PC. In the parlance of the RS232 standard, the PC falls into the category of Data Terminal Equipment (DTE). It will receive data on pin 2 of its DB9M connector, and will transmit data on pin 3. The KX3 is categorized as Data Communications Equipment (DCE). It will receive data on pin 3 of its DB9F connector, and will transmit data on pin 2. If for some reason you need to interface the KX3 with another DCE device, you’ll need to use a null modem adapter, or you can replace the DB9F above with a DB9M and swap the connections for pins 2 and 3.

I realize this isn’t exactly rocket science, but since I went to the work of figuring it out for myself, I thought I’d post it in case anyone else needed the information.

2 thoughts on “Roll Your Own Serial Cable for the Elecraft KX3

  1. I am working on a loop antenna tuner/controller and am interested in how to get the frequency information from the KX3’s serial link. Once you have the serial link, how to you poll the frequency?


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