CAT Interface for the FT840

The interface shown here is the same as published in the ARRL Handbook and my contribution to the project is only to the extent of developing a PCB. Virtually all modern Amateur Radio transreceivers have provisions for external computer control. Most hams take advantage of this feature using software specifically developed for control, or primarily intended for some other purpose (such as contest logging), with rig control as a secondary function.

Unfortunately , the serial port on most radios cannot be directly connected to the serial port on most computers. The problem is that most radios use TTL signal levels while most computers use RS-232-D. Interface described here simply convert the TTL levels used by the radio to the RS-232-D levels used by the computer, and vice versa. Interfaces of this type are often referred to as level shifters. This interface was designed for and test on the FT-840 Transreceiver. A PCB for the project is available with me if anyone is interested in building one. I don't see any reason why this project cannot be assembled on a verro board for use.