Yaesu FT-100 PC Link Interface for Digital Modes

Here i present the guidelines to build a PC link interface for Yaesu FT-100. This interface alows you to transmit and receive audio signals from a sound card in order to operate HAM digital modes (FT8, PSK31 etc.).

Additional information is available on my blog http://eaktronix.com

You will need these components:

- 600 ohm 1:1 transformer (e.g. Bourns LM-NP-1001-B1L) (2 pcs)

- NPN transistor 2n2222 (1 pcs)

- Diode 1n4148 (2 pcs)

- Trimmer 1kOhm (2 pcs)

- Capacitors and resistors (cf. step 2)

- DB9 connector (1 pcs)

- Jack 3.5 female connectors (2 pcs)

- Some box

The PTT command is based on the work of WA2NKF (http://k0lee.com/ft100/pskft100.htm) but with an additionnal protection from OZ6YM (http://www.planker.dk) on audio channels. This protection is based on a 600 ohm 1:1 transformer and avoids the damage of the rig from a DC voltage present on the output of the soundcard.

The sound level on a soundcard lines is adjusted with a 1 kOhm trimmer. In order to trig the PTT a DTR (pin 4) or a RTS (pin 7) signal can be used. In my case i use a DTR.

The circut was designed on KiCAD and milled on a CNC machine, but you can use a standard etching method. Gerber files are available on my blog.

Solder all components and put into some box. Be aware, the pins of the transformers should be isolated from the bottom ground plane.

Enjoy !

F4HWK