# Case Study 2: 60Hz Humming Noise on Certain Frequencies

## Symptom:
- A distinct hum at multiples of 60Hz (50Hz in some regions).
- The noise is stronger on some bands than others.

## Analysis:
- This is likely power-line interference, possibly from poor grounding, power supplies, or nearby transmission lines.
- Nearby appliances, dimmers, or solar inverters could also be culprits.

## Mitigation Steps:
1.	 Power Down Test:
- Turn off all breakers in your home, leaving only the radio on battery power.
- If the noise disappears, it’s inside your home. If not, it’s external.
2.	Use a Portable AM Radio:
- Tune to a quiet frequency and walk around.
- If the noise gets stronger near power lines, suspect arcing insulators.
3.	Mitigate Internally:
- Add ferrites to power cords of computers, routers, and LED lights.
- Replace noisy switching power supplies with linear ones.
- Improve station grounding with a dedicated RF ground.
4.	Mitigate Externally:
- If a power line is the cause, document the issue and report it to the power company.
- Use a small loop antenna to confirm directional noise sources.