Building PC / TXRX Interface

One of the (many) key drivers for me to upgrade my license was to have access to digital modes. My background is in computing and I've wanted to combine that with my interest in radio. So, as a close contender for my first project post license upgrade is the building of an interface between my computer and radio.

Sure, you can buy a commercial one, or even one of the radio specific cables from the manufacturer. But, what's the point of all that study if you don't go and apply it and get building.

Therefore last week I grabbed all the bits I needed, and as of last night my build is well under way. My build is based on the schematics by a fellow VK1er Waldis (VK1WJ) seen on his Digital Modes Primer. I'm going for the one with full galvanic separation and the diode on the RTS/PTT line I'll be swapping for an LED to hopefully help illuminate me to at least whether I've got the software working correctly.

For connection on the TXRX side I'll just have one cable with a PS/2 style mini-din connector. This will connect to the 'DATA' port nicely on my Yaesu radios (both the FT-817ND and the FT-7800). This 'DATA' port is specifically meant for data modes and is different to the 'ACC' port which is what one would use for CAT control (and is only on my FT-817ND as the FT-7800 has no CAT interface I think…). The 'DATA' port is such that it provides a fixed audio output level and also provides access to PTT and ground just like the mic input I was originally planning to use.

Anyway, as I said the build is underway. I've drilled the holes in the enclosure, installed the isolation transformers and wired up the cables for the audio in and out on the PC side. So tonight I'm hoping I can probably get everything else wired up and, fingers crossed, be complete. Once done I'll provide some photos – although, you're still waiting on photos for a few other projects ATM. 😉

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