Many modern-day amateur radio programs use a single USB cable between the transceiver and computer to transfer three basic types of information; audio signals which can include SSB, RTTY, digital or CW signals, critical transceiver control and polling data, and transceiver transmit activation signals. Any RFI (radio frequency interference) in your radio room could disrupt the data flow on any one of these signals, necessitating a program reboot or, worst case, a system reboot.
One purpose of this circuit design is to greatly reduce the chance of RFI interrupting the data flow by separating the three specific signals into separate pathways between the transceiver and the computer; the audio signals, the transceiver control and polling data, and the transmit enable signal.
Another purpose of this interface is to eliminate the time-consuming nuisance of having to adjust Windows® sound settings each time you switch from phone to digital to CW or back again. This interface will allow up to four separate amateur radio programs access the transceiver’s PTT (push to talk) line to key the transceiver.
Many modern amateur radio programs state you must use CAT (computer aided transceiver) to key the transceiver, yet they still provide the choice of using a communications port (COM Port) for keying. As long as you can activate the PTT line in your transceiver, you can key your transceiver and not have to use CAT. This circuit eliminates the need to use CAT.
Putting the CAT Back in the Bag
I designed this interface because using CAT with many of the new digital modes caused me a problem when I wanted to switch quickly from digital to voice mode. Digital modes need some type of codices
