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FT8x7 OptoCAT - The safe RS232 CAT interface and PA buffer for Yaesu FT-817, FT-857, FT897 and FT-100 rigs

Here is a simple interface for the Yaesu FT-100 and FT-8x7 series (817, 857 and 897) with a buffer to switch on TX an external Power Amplifier (PA) or transverter.

Like all my interfaces, also this one is optocoupled to electrically isolate the rig from the PC.

I choose two, easy to find, optocouplers: one is the cheap 4N25 and the other is the CNY17-3 (higher CTR than 4N25).

To power the circuit on PC side, I use the DTR and/or RTS signals of the PC: with all the software I tested, these pins are, or can be set, at +12V.

If you don't need the PA buffer, you can build only the CAT, it is very simple (only 8 components) and it fits on a very  small box.

Instead of buy a Mini DIN 8 pin male connector and going mad soldering the wires to the micro pins, I bought a cheap APPLE printer cable and I cut and used a piece of it. The one I used has this colored wires: pin 1 = brown, pin 2 = red, pin 3 = orange, pin 4 = yellow, pin 5 = green

I built the interface using the ugly construction on a little unetched piece of copper-clad circuit board that fit in a little plastic box, as you can see in these pictures (click to enlarge the pictures).

If you want, you can add two toroids, like I did with K2 interface, just to stop better any RFI...

The interface is tested and perfectly working at 4800 and 9600 baud (not working at 38400 baud) with FT817 Commander and Writelog; I think that it would work with any software that don't needs the handshake to the radio with RTS and CTS.

Ciao, 73 and good work

Guido, ik2bcp / iu2r / ab9dg

Any question and/or comment to ik2bcp AT