On Fri,1/30/2015 2:49 PM, Jim Garland wrote:
But, like I said, maybe I'm not following something.
Right -- you are not. First, you don't understand what common mode is. Second, you don't understand the choke. A ferrite common mode choke STARTS OUT as a lossy inductor, but one with shunt capacitance. This forms a very low Q resonant circuit (typically 0.4), and thus a very broad resonant peak. It is the resistance around resonance that forms an effective common mode choke.
I've discussed this in considerable detail in tutorial form in k9yc.com/RFI-Ham.pdf and some of that material has been added to the ARRL Handbook. There's also a pdf of the slides that go with an RFI tutorial that I've done for several ham clubs. It's on my website -- k9yc.com/publish.htm I suggest that you study these two pieces. It's far too much work (and probably boring for many readers of this list) for me to post it here.
73, Jim K9YC _________________ Topband Reflector Archives - http://www.contesting.com/_topband
