Use the "Scientific Filter" and select a curve that emphasizes the mid-range frequencies.

Old radios had limited frequency ranges. Use an EQ plugin to cut out the deep bass and very high treble. A good starting point is a High Pass filter around 600Hz and a Low Pass filter around 3.5kHz .

Use keywords like "radio static," "tuning buzz," or "frequency scan" .

Use the "Trickster" or similar voice-changing filters in the audio editing menu after recording a clip.

If you need immediate "foley" (performed sounds) or background noise, look for these specific elements: