Hello All,
During the past almost 3 years I have tried to find the source of this very annoying noise. Putting a transistor radio near an incandescent light bulb results in overpowering and overloading hum.
Attaching the ground terminal of an outlet to G on a radio INCREASES hum. I have checked and there is a ground wire connected to the supply cold water pipe before the meter and it is correctly connected to every receptacle in the house. I used an outlet tester and all outlets are "correct". If everything is shut off the hum remains and refuses to go away. This is why I wanted to try a separate antenna ground spike.
I tried AC RFI line filters and they do absolutely nothing because the antenna is picking up this annoying hum. I can take a transistor radio outside away from the house to test it. But there's nothing that I can do to stop the noise.
How do I get rid of the noise on the AM broadcast band?

Thanks,

Dave

Go to your breaker box and shut off every breaker, or pull every fuse. No exceptions. Then check your radio for hum as you customarily do. No hum: problem is inside your house, and you can probably fix it. Hum still there: problem is external to your house, and you probably won't be able to do much about it.

If the hum goes away with all breakers tripped off, restore the breakers one at a time, checking with the radio for hum with each breaker reset. Eventually you will find the circuit which is feeding the hum generator.

I recently had a problem like this suddenly occur and suspected that the control pot on one of my SCR lamp dimmers was going bad. As it turned out, it was a cheap Chinese blowdryer bought by my wife - the thing generated RFI whenever it was plugged in, even turned off!

Most common household RFI sources are (1) SCR dimmers; and (2) desktop computer power supplies. There is no cure for SCR dimmer noise aside from replacing them with plain switches; a RFI filter is effective for computers but it must be installed right where the computer plugs into the wall outlet.