[Hallicrafters] SX 101A hum

[Andy Bullington]

It's winter project time so I've decided to revisit my SX 101A. I've 
realigned it with good results but on using headphones I'm noticing an 
annoying hum. It doesn't seem to be a tube , there is a 60 cycle hum even in 
standby mode. Using a speaker the hum isn't as noticeable but still there. 
The overall audio sound is very smooth and better than my NC303 but the NC 
303 is hum free. I've long ago replaced all the paper caps and electrolytics 
and also some out of spec resistors. At the same time I did all that work I 
replaced the power cord with a 3 prong. I'm wondering if I did that wrong.
Any help for a poor technically challenged musician would be much 
appreciated. Here's where I stand: I get hum even in standby or with the 
audio turned all the way down or the audio tubes removed. It's not run you 
out of the room hum, but it shouldn't be there. Is it something in the power 
supply? Thanks in advance.
                     Andy W1AWB