I have a pair of Truecharge 20's on my boat and have the same problem.
Terrible noise on my shortwave receiver.
I sent a note to Xantrex asking about solutions and they never replied.
Good customer service.
On their web site they have an FAQ page that comments on this problem so I
don't think it is so uncommon. If I recall correctly they mainly talk about
filters on the output lines. I didn't think this would help as my portable
is not picking up interference through a power supply line. I guess the
output leads could radiate so I will try the twist method. Grounding the
cases had no effect.

"Ron" wrote in message
...
I recently replaced my old old battery charger with a Xantrex Truecharge
40+. It works fine except now I have all kinds of noise interference on my
am/fm radio and lines across the TV screen. I called Xantrex and they
could
offer no solution to my problem. Said I was the first one that had this
problem. Is anyone else experiencing this problem or is it just my
problem.
Any suggestions on how to correct the problem? I know it is the charger
for
when I remove power from the charger the interference goes away. When I
power it up again the noise returns.
Thanks for comments.