Modern HF noise has a different profile than it did twenty years ago. Solar inverters, switching power supplies, and LED drivers have replaced a lot of what used to be quieter analog electronics, and tracking down the source takes a methodical approach.
The modern usual suspects
Solar panel systems, particularly the DC-to-AC inverters, are one of the most common sources of persistent, wideband HF noise in residential areas today, whether it’s your own system or a neighbor’s. Switching power supplies, the small, efficient wall warts and USB chargers that have replaced heavier linear supplies, are chronic offenders. LED lighting drivers and cheap electronic devices with poorly filtered power supplies round out the list of usual culprits.
Finding the source with a portable receiver
A battery-powered handheld or portable HF receiver, disconnected from anything wired into your house, is the single best diagnostic tool for tracking down noise. Walk the property, and even inside the house room by room, watching the noise level rise and fall as you approach or move away from the source. Killing your main breaker at the panel briefly (if it’s safe to do so and coordinated appropriately) can quickly confirm whether the noise originates inside your own home at all, versus a neighbor’s system or utility equipment.
Fixing it once you’ve found it
For your own devices, ferrite chokes clamped on power cords near the source often knock down the noise significantly, and replacing a particularly noisy switching supply with a better-filtered one sometimes solves the problem outright. For noise coming from a neighbor’s equipment or utility infrastructure, the ARRL has documented processes for working with utilities on interference complaints, though results vary considerably depending on the utility and the specific source. Persistence and clear documentation of the noise source help your case considerably if it comes to that.
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