Dual CI-V


I experiment around with SO2R configurations. In this case I needed something that looked like two CT-17 boxes (about $240). The CT-17 is really very simple, so I decided to layout a board and build one myself. It would work for Icom rig control as well as my special purpose.

The IBS-1 (Intelligent Band Switch) is sold by Array Solutions. The unit as shipped is configured to obtain the band information from either the DIN-7 socket of a Yaesu radio or the CI-V bus of an Icom radio. Other radios can be accommodated by cutting off the Yaesu connector and connecting the appropriate wires to the BCD output of a radio or parallel port configuration. I tried connecting the serial output of my Omni VI+ to the IBS-1 CI-V port and it sort of worked - the IBS would recognize the broadcast signal, but would drop the band after a few seconds.

Since I already had my FKeys utility and it knew about the frequency information (from WriteLog), I decided to add enough code to FKeys to let it open (two) serial ports and pretend to be an Icom radio broadcasting it's band data. Once I had this working I wanted to make a cheap pair of CI-V interfaces to convert the RS232 levels from the serial port to the TTL levels of the IBS-1.

The first circuit here is a dual CI-V interface implemented using a Maxim MAX-232 chip. The circuit is one adapted from one in the ARRL Handbook. Below are a circuit diagram and a PCB layout.

Parts list:

QTY Description Jameco DigiKey
1 MAX232
4 1 mfd / 35V tantalum capacitor
2 470 ohm 1/8w resistor
1 7417 hex buffer
Power Supply
1 7805 voltage regulator
1 1N4001 diode
1 4.7 mfd / 50V capacitor