ok – this should be the final post….   I did one more batch of updates…  this time I designed for EMI.  Not only did I ensure I had full isolation between the radio and computer, I also added some ground plane breaks to control noise.  I also did some trace routing to keep signals routed directly above their returns, and some other geometry fixes.

In order to make the board a bit smaller, I removed the perf board section, and moved some components around – the final result being a board just under 3″ x 3″ (69mm x 69mm)….  the nice part is that easyEDA had a sale, too – I ordered 10 boards for $14.

I did have a keep-it-simple, stupid moment….   the CIV to TTL interface components were unnecessary – CIV is designed to allow direct connection of TTL TXD and RXD, so I can just connect them together in the cable for a CI-V radio.  MUCH simpler (lower component count, plus the prototype circuit I found didn’t work)

Next, I need to include the designs for the interface cables – once I get those formalized, and get the first run built, i will upload the gerber files, as well.