It's an all-analogue design, so probably could be considered a bit dated when the input circuitry, and possibly even more, could now all be done on a DSP chip.  But at least it's simple to build and to visualise!

There are three PICs inside it, two doing completely trivial tasks,  but was the easiest way to implement them; the other is a DDS tuning controller.  Source and Hex code for all of them can be downloaded from the link given in the .PDF

In view of the complete lack of interest in PCBs when I mentioned this earlier - I shan't be designing one.  My breadboard PCB design, shown in the photograph at Figure 6,  isn't really suited for distributing as it has been hacked around more than a bit.

Andy  G4JNT