I had an interesting conversation with a salesman at Ham Radio Outlet about putting up an antenna inside a house. He told me that house appliances, florescent figures and many other devices would interfere with an indoor antenna. That evening I connected my Yaesu FT-817 inside my home office to function as a short wave receiver. I hooked it up to my Spider antenna with a 20 Mhz coil. I put the radio into scan and got nothing but a lot of noise. A day later I pulled off a Craftsman portable drill battery off its charger and unplugged the charger while the Yaesu radio was set for 10 Mhz, Fort Collins, Colorado, WWV, National Bureau of Standards station that should be received. All of a sudden the radio was quiet except the click audio of the WWV station sending out timing signals. I reconnected the Craftsman charger and the horrendous noise returned. My Yaesu radio now functions quite nicely with the Craftsman charger disconnected.
Problem Charger: Craftsman 45 Min Quick Charger, model 315.259260