The hand held portable AM radio and unplugging wall warts, consumer electronics, and table lamps should help isolate the source. As a long time radio listener, SWL, and DXer, I have had a myriad of tough interference sources. Years ago, it was the power lines out front - cracked compression insulators - but lately, it's my consumer electronics. The lite weight wall warts, actually switching power supplies rather than the older, heavier, and quieter transformer operated analog supplies, on your modem, router, and even the $40 digital TV tuner the Feds paid for when the switch to digital TV occured some years ago, have been isolated here as horrible noise sources. The huge 25" LCD screen on my PC monitor is appreciated by my 'mature eyes' - not so much my ears.

Distance and changing the alignment of the AM radio's builtin loop antenna helps. I have the Tivoli Model One above my reloading bench. A great radio, it's weakest link is the variable capacitor used to tune it - mine got scratchy in warranty - they said that was common and there was no fix - just tune it back & forth! I bought a Boston Acoustics 'Receptor' - better sound, too. It's ~ 3 ft from the PC and CFL-equipped drafting lamp. I have CFL's everywhere - no problem.

To help weak AM reception, consider a magnetically coupled tuned loop, like Kaito and Grundid market. My Grundig AN-200 was $27 via AMAZON with free s/h. Good luck!

Stainz