By connecting the radio's power leads directly to the battery and by installing coaxial capacitors in the alternator leads 

By installing a high-pass filter in series with the radio's power lead and a low-pass filter in parallel with the field lead

By connecting the radio to the battery by the longest possible path and installing a blocking capacitor in both leads

By installing filter capacitors in series with the DC power lead and by installing a blocking capacitor in the field lead



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