Sounds like your charger is a switching regulator, which are very RF noisy. There may or may not be a solution, other than changing the charger. Other option is to run the power leads through a RF choke of some sort, like a "Snap Choke". Alternatively, wrap the wires thru a ferrite choke, like those found on the ends of monitor cables or similar.
I suspect the charger is producing enough RF that it is getting into the power panel.
However, if the RF interference is simply radiating from the charger itself, you would have to replace the charger with one that is RF quiet...
The RF seems to come about under load, when the charger is actually running with enough power to produce the RF via power spikes. This type of RF noise would be worse on the AM band, and less noticeable on the FM band.