This weekend, I met some local ham geek types at a restaurant for breakfast. The group is really focused on QRP, but they asked me to come and show them D-RATS. They’re mostly hardware-focused, and probably more interested in the world below 30MHz than anything else (thus making D-STAR relatively low on their list of interests). Either way, I’m not one to turn down a chance to geek out with smart people, especially at breakfast.
While I was there, Jason NT7S pulled out his EeePC running Linux and fldigi, which I also run. I noticed that his screen was displaying the rig frequency and proceeded to ask him if he had a CI-V interface for his radio. Later, I learned that this is the default layout in the newer version of fldigi (to which I have since upgraded), but his answer was “yes” anyway. In fact, he too has an ICOM IC-718 and like me, doesn’t like buying cables and interface hardware for insanely inflated prices. He mentioned that he was using a homebrew interface circuit and pointed me to it. I had seen this particular site before, but gained new motivation knowing a living, breathing person who had successfully used it.
This afternoon, I set out to prototype the circuit on a breadboard and was tickled when I got it working. I quickly transferred all of the components to a small perfboard mounted in a project box and ended up with this:
Now, I can use another serial port to interface with the 718, which gives me control over the settings from the software, as well as a live frequencyin my logs. I’m looking forward to the next contest so I can try it out. Before then, I may add an external LED (there is one surface-mounted on the board already) to indicate operation, a panel-mount jack instead of the pigtail, and an additional transistor to key the radio from the RTS signal. As it stands now, I’d still need to use my RigRunner box to key the radio, and thus two serial ports. Unfortunately, the 718 doesn’t allow you to key the radio with CI-V, but adding some additional components to my box will make it possible to cut it down to a single serial port by using the RTS line.