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](https://www.florian-wolters.de/images/80ffca61-0f2b-4ca6-a544-a7de8093c8c2.jpg)
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](https://www.florian-wolters.de/images/c82d0a9e-b418-4057-8e10-fac59491b91f.jpg)