So back in around 1998/1999 I was getting into Amateur radio and Malcolm (G0WYW) gave me a Tait 535 which he had performed the 2m conversion on and programmed for the local packet radio station (I had – and still do have a PK232).

I used this for a little while and eventually started looking at how this radio was programmed – a diode matrix board. A light lit up and I realised that there are just 16 pins that select the tx/rx frequency based on binary and decided I’d have a go and producing something that was able to synthesize the whole band.

Back then I was playing with Pic chips (the 16 series) and started work on a Pic16F based project along with two CD4094BE shift registers chained together to program the pins via a few I/O’s from the PIC and a rudimentary keyboard matrix and 7 segment led display.

I quickly hit the limits of that architecture and stopped working on that and it stayed packed away with much of my gear when I took a long break from the hobby.

Cue COVID and having to find things to amuse myself and I dug out my old gear and pondered on how easy it would be with the massive improvements in MCU over 20 years and to see what could technically be possible. Probably not worth it so much on this old radio but it was a challenge and one I’ll start documenting here over the coming weeks.