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

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


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