These pictures show the prototype interface under construction.
The 3.5mm audio plugs to connect to the PC sound card. In this example, the microphone input is a mono socket, and the headphone output a stereo one. Dual screened audio cable is used to connect to the interface box.
The 9-pin D-type socket connects to the PC serial port, so that the RTS line can control the transceiver's ptt. Screened audio cable is used to connect to the interface box.
In this case, the transceiver interface is a 13-pin DIN plug. The pins are much easier to solder if the chrome plating is first scraped off. Heatshrink sleeving is used to prevent the risk of shorts between the close-spaced pins. 3-core screened cable is needed to connect to the interface box (I used 4-core, and had a spare red wire).
The simple interface circuitry may be constructed easily on Veroboard...
..and mounted in a suitable box.
This prototype has been tested successfully with both FT817 and TS2000 transceivers, and with two different PCs.