[Elecraft] Capicator Size for filtering across battery power

[goldtr8 at charter.net]

Gents,

My setup uses four ()4 12v batteries in parallel for powering my K3 and 
SGC powercube amp that I float with a battery maintainer.

I believe that I have an RF problem with the power setup.   I have put 
chokes in the power leads to the equipment but at certain times I can 
hear the ferrites buzzing with either the digital code being sent of 
matching my voice with SSB.   The chokes are clamp on types.  I am not 
observing any RF problems or reported problems on the air.  But I think 
that something is not right as of yet so I want to go after it to make 
my shack even better.

It has been suggested to me by a ham on the air that batteries just pass 
this thru as they have no filtering capability.   His suggestion is to 
but a bit CAP across the batteries to kill this phenomenon.

So my question as I am not an EE by education is how would I properly 
pick a CAP size and would different materials that CAPS are made out of 
make any difference.

It would be easy to go out and get a large CAP like used on car stereo 
systems but I want to have a better shot of fixing it right than just 
hacking away.

As always thanks in advance for your help.

~73
Don
KD8NNU
FH#4107