Homebrew Elecraft Kx3 Serial Exchange Cable

I had a KXUSB version of exchange cable with the radio but it stopped working and I had to upgrade the firmware. The new serial cable from Elecraft was $29.95 USD + approximately $40 USD for Shipping to Canada. So I decided to make a cable at home. 

Step One: To begin this project I bought “9 Pin DB9 Solderless Terminal Female Serial RS232 Adapter”

Step Two:  I cut the not working 3.5 mm cable 

Step Three: Attach the cable wires with 

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

The Cable is now complete and works efficiently with Kx3 Software. I am able to upgrade the firmware of the radio. 

3 comments

  1. F4HHY

    DB9F Connector Connects to 3.5 mm Audio Plug

    This is the correct Way to connect

    pin 2 (TX to PC) ring pin 2 (TX to PC) TIP

    pin 3 (RX from PC) tip pin 3 (RX from PC) RING

    pin 5 (ground) sleeve
    pin 5 (ground) sleeve

  2. F4HHY

    This is the correct Way to connect

    pin 2 (TX to PC) TIP
    pin 3 (RX from PC) RING
    pin 5 (ground) sleeve

  3. Fred - VK2WS

    If I wanted to make a USB to TRS cable, would it require the same connections?
    Could I use a USB to serial (or a USB to TTL) convertor board and simply wire the Rx (as marked on the USB-Serial convertor board) to Ring and the Tx to Tip?

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