[Elecraft] Capicator Size for filtering across battery power

[David Moes]

On 10/6/2012 5:15 PM, goldtr8 at charter.net wrote:
>   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.
That is interesting.    I suspect that they are reacting to the 
elecromagnetic field created by rapid current fluctuations in the DC 
lines rather than picking up RF.    RF would be far to high a frequency 
to cause a ferrite to audibly buzz or rattle.

I too run batteries on my K3 when I am at the cabin. and cant say that I 
am aware of ever suspected RF issues in the DC power system other than 
with  the charger which is horrible for noise  on the reciever and any 
attempts to tame it have failed so I just disconnect it when I'm on the 
air.
As far as RF in the power system   if it really is a problem  I would 
put a small cap across the input terminals to the rig.   for RF id say 
.01mf   ceramic disk.    if you are attempting to filter ripple from a 
generator or charger  which is not an RF issue  I would first connect 
the charger as close if not directly to the battery terminals.   then 
add a large  say 50000 mf 16 to 20V capacitor near the power terminals 
at the rig.   this will filter ripple but wont filter RF well so add to 
it a small .01mf ceramic capacitor for any RF.
> I am not
> observing any RF problems or reported problems on the air.
If you are not having any issues than I wouldn't worry about it. RF 
issues in the power source like batteries are not often a problem so 
long as things are wired and grounded properly

73 Dave