[RFI] When AC filtering actually makes it worse

[Aaron Kreider]

I'm constantly learning new things about RFI in my efforts to improve my 
noise floor.

I've got AC power line noise - probably in the house wires and power 
lines all around the neighborhood.  Recently I noticed that it was worse 
than normal in my antenna.  The solution was to have my radio and 
antenna interface plugged into the same filter bank on the Isobar power 
strip.  When they are on different filter banks I can get up to 20 db 
more noise!  I think what happens is that my AC is poorly grounded - so 
my coax shield stops working. Does that make sense?

Grounding the coax shield (with a 15 foot wire running into a copper 
grounding rod) is a lot less effective than putting the two AC/DC 
adapters on the same filter bank.

Is there anything else I could learn from this finding?

I forget if I've posted about this before -- I may have learned it and 
than forgot it!

Aaron

QS1R
Wellbrook 1530+ in backyard
Philadelphia, PA