Computer audio connections for ham radio
Apple has adaptive impedance for the TRRS connector on MacBook. Windows Logo certified computers likewise have standards for voltage levels and impedance for audio input and output. Instead of the built-in computer audio interface, we generally recommend using an external USB sound card to reduce risk of damage to the computer in case of voltage surges. Consider two 3.5mm TRS cables (one each for input and output) to the radio connector (typically the microphone connector that also has fixed level audio output) and a USB sound card. The USB sound card can be used on different computers once it’s known to work with the radio audio interface. At a minimum, a grounded coaxial surge protector should be used in the antenna feedline along with a fused, surge-protected power supply. Consider using an older laptop that still runs a currently supported operating system as a dedicated radio computer. This avoids risking an expensive laptop when an older laptop is often more than adequate for digital ham radio modes.