[RFI] Dell D505 PA-10 PS

Jim Brown jim at audiosystemsgroup.com
Fri Aug 10 13:35:11 PDT 2012

On 8/10/2012 1:19 PM, Dale wrote:
> For starters, go to the K9YC website and read the mountains of info Jim has posted there.  You must read carefully and thoroughly - don't be in a hurry.

That's http://audiosystemsgroup.com/publish.htm

First study http://audiosystemsgroup.com/RFI-Ham.pdf

When attacking your problem, first diagnose it more completely.

1) What ham bands are affected?  Where is it worst?

2) The trash is usually radiated by cables connected to the noise 
source. Could be the power cable, or the video monitor, or the USB, or 
all of the above.  For testing, try removing everything but the AC cable 
(with the computer running) and see if the noise changes on any of the 
bands.  The video monitor itself, or it's power supply, can also be a 
noise generator. (You didn't say if it was a laptop or desktop, so I'm 
assuming a desktop.

3) The power cable is USUALLY the worst offender.

4) Once you've figured out what bands are affected, use the curves in 
Appendix One as guidelines for winding one or more chokes to cover those 
bands.  Appendix One also lists part numbers and distributors of 
suitable products.

Yes, it's good to see that Fair-Rite has added larger the toroid core in 
a few mixes, but you don't need anything that big for this application.  
The listed cores are plenty big enough.  The big ones are great for 
winding low frequency chokes with big coax. .
73, Jim Brown K9YC

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