I was wondering how the Radio interfaced with a TNC. I thought the computer sent digital data (in a serial format) to the data port on the radio, but from what I read online, it is not a data port.
This jack is variously called "data", "packet", "auxiliary", etc, but actually there are no data connections on this connector. This IS NOT a serial data or RTTY direct FSK port. Only various forms of receive and transmit audio are present. The connector provides receive audio output at a fixed level of about 100-300mV, transmit audio input at about the same level, transmit PTT keying, receiver squelch status (COR), and ground/common.
But on the yaesu's manual, it mentions about packet data rates. So if the signal received by the radio over the data port is good ol' FM, how can it have a bit rate?