Homebrew CAT Interface

This is another note to myself about self made CAT control cables for my ICOM / Yaesu transceivers. These should be easy to build and for portable use. Both manufacturers sell many-dollar interface adapters while schematics and protocol analysis show that this is absolutely overkill. So I built my own from a cheap USB serial interface cable based on the famous FT232RL chipset.

ICOM and Yaesu CAT cables
ICOM and Yaesu CAT cables

The pinout of my cables from eBay are as follows:

  black  --- GND
  red    --- 5v0
  green  --- TX (FT232 ->)
  white  --- RX (-> FT232)
  yellow --- RTS
  blue   --- CTS

For both variants I connected RTS to CTS in order to trick the hardware flow control. For Yaesu RX, TX and GND can be connected straight to the pins on the 8-pin miniDIN connector. The CI-V variant for ICOM requires two extra components because it is a single wire half-duplex interface. I took the schematic from [1]. The diode and resistor were fitted into the headphone jack though there is little space.

Details of the Headphone Connector
Details of the Headphone Connector


[1] https://www.maniaradio.it/forum/showthread.php?tid=458