[Eric Adams]

I've got a strange one. All electrolytic and wax caps replaced. Resistors replaced as necessary. Tubes tested. Set aligned on both AM and FM.
The problem is that I get a hum on AM only and only when on a station. In between stations on AM is silent as well as FM.
Any thoughts?

Thanks,
Eric
Schematic:
http://www.nostalgiaair.org/Resources/251/M0015251.htm

[BrendaAnnD]

Selective hum like this is usually environmental. Try moving the radio to a different area of the house and see if it goes away. My workbench is insane for reception problems. There's some kind of field there that creates a ton of RFI, but if I move the radio under test off of the bench, even just a couple feet, all the noise goes away. Before I discovered this, it nearly drove me mad trying to figure out what was wrong with the radios.

[codefox1]

Agree, try moving set around. Most likely a really old dimmer, imported unshielded power supply, shut your bench down completely first.

[Eric Adams]

Thanks BrendaAnnD, out of the basement and away from my bench the hum is minimized. It's just strange that this is the only radio that I've had this issue with.