This cable is designed for quick and easy CAT control and/or programming of Yaesu FT-655 transceiver. It controls the radio’s frequency, mode, and other functions by computer. It requires an external 9VDC battery (not supplied), which should be connected to the DC lead fitted to the DB9 plug. The internal converter circuit board mounted in the DB9 plug. This cable does not include any manuals or instructions for use. Therefore, it will be assumed that the purchaser is knowledgeable in using the cable for the applications it is designed for. Please note that we supply the hardware only, we don’t supply the programming software.