[time-nuts] Power supply for time source concerns

[jimlux]

On 12/23/19 10:17 AM, Taka Kamiya via time-nuts wrote:
> I think the conversation is going into an area way beyond my initial intent.
> My goal is to have a "good enough" source for 24V to run multiple time sources.  Yesterday, I measured the output of switcher I've been using for testing purpose only.  Holy cow it's dirty!  120mV peak-to-peak wide band noise.  Put one ferrite bead on plus side and it had an amazing result.  Broadband noise disappearance and periodic pulse (still 120mV p-p)
> My goal is to have about 5mV p-p or lower capable of delivering 20Amp in switching arrangement.  It's easy to do with linear regulators but it makes the room awfully warm.  Why 5mV?  Because it is good enough.  If more is necessary, it will have to be dealt with locally inside the time source itself.  Cabling can pick up that much easily.
> 


Check out Jim Brown K9YC's compendia of filters - he's done measurements 
on a variety of ferrite mixes in a variety of configurations (number of 
turns, number of cores, etc.)

http://audiosystemsgroup.com/RFI-Ham.pdf
http://k9yc.com/2018Cookbook.pdf


He's done a lot of work to take the raw material data sheets and turn it 
into practical recipes.

Of course, you could get yourself a copy of Snelling's book on "Soft 
ferrites: properties and applications" which is the recognized tome on this.