Radio has static when I turn it on 1990 Nissan 300zx

If that's only static with no talking, suspect the antenna or a problem in the radio. If the reception is normal with the engine not running, but there's a loud whining noise that increases in pitch as engine speed increases, a good suspect is the generator. Temporarily remove the drive belt, then start the engine. If the noise doesn't occur, put the belt back on, then have the charging system tested by your mechanic, not at an auto parts store. In particular, for this symptom, I want to see "full-load output current", and "ripple voltage". If the generator has one failed diode of the six, ripple voltage will be very high, and you'll hear that in the radio.