Reducing RFI off the powerline into radio set

[wa2ise]

Too another angle in getting better reception of weak AM radio stations. This one is to restrict RFI riding on the powerline from getting into the radio. Took an EMI filter network from an old computer monitor, like this below:

and placed it between the radio's power cord and the powerline input of the radio circuits. You can tell if this is a reasonable thing to do by this test: While listening to a weak station with powerline RFI buzzs, disconnect the power plug and quickly listen to see if the buzz goes away before the station and the radio dies. We're talking about 1/4 second, before the mail filter caps in the radio's power supply looses charge. You can repeat this test after installing this filter and see if any buzz left over still stays on the station after pulling the plug. Idea is that you effectively pulled the plug on the path the RFI was taking. That your plug in radio acts like a portable on batteries.