Case Study 3: Periodic Short-Duration Pops in Audio

Symptom:

  • Random popping or clicking sounds in the receiver audio.

  • No specific pattern but seems linked to household activity.

Analysis:

  • This suggests impulse noise from electrical switching events.

  • Likely culprits: Thermostats, refrigerators, motor brushes, or light switches.

Mitigation Steps:

  1. Identify the Source:

  • Listen in AM mode on a quiet frequency.

  • Have someone turn appliances on/off and note when the noise occurs.

  1. Suppress Arcing Devices:

  • Add capacitor snubbers (RC networks) across relay contacts.

  • Replace old motors or switches with modern, filtered versions.

  1. Improve Station Filtering:

  • Use ferrite clamps on power leads of affected devices.

  • Install a mains power filter for the radio station’s AC line.