One of the challenges we faced for the CQ WPX Contest was ensuring reliable communication between the computer and the Icom transceiver. The originally intended controller occasionally had problems both with starting up and with communication between these devices. Since we use the DX cluster and Bandmap in the N1MM log, as well as software-controlled tuning to a specified frequency or band, this is a very important feature for the operator. There’s nothing worse than a “frozen log” during a pileup. For this reason, we built an Icom CI-V interface.
The circuit is essentially a very simple bidirectional voltage converter with two transistors and a few components, as shown in the schematic. The photo shows our solution on a piece of universal printed circuit board. Don’t forget to enable the power supply to DTR in the log.
Schematic of the Icom CI-V Interface