...then don't worry about using it. That's my experience around my own home as well as working with clients. If all your other devices are also working as they should, then it's a done deal. Writing en entire treatise on the merits of using ferrite cores makes no sense when you could simply do some digging on your own and come up with something quickly. Using well shielded/insulated cables is usually sufficient.
My new Samsung plasma television (PN43E450) came with three ferrite cores (Todaisu HT2629S), a.k.a. ferrite "rings" or "collars". Instructions say I should install one on each end of power cord, providing a maximum distance from the plug (at each end) for core installed. But it doesn't say why I should install them, or if they sometimes might not be needed at all.
A third ferrite core is provided for the antenna cable. Well, I don't have an "antenna," my t.v. signal arrives via AT&T's Uverse (a telephone line?). Should I treat that the same as an antenna? If the cores are always needed, why does Samsung leave it up to the consumers to install them, or not, and leave placement up to us as well? The arrangement seems to imply they are either optional or sometimes unnecessary.
I searched CNET forums and found several old posts but, in each case, found no real help. Maybe I misread the tone, but in one case, a reply (by R. Proffitt) seems to come from a someone who knew the answer but felt a snarky response was all that "patshak" was due. Again, sorry if I misread the tone, but if all you intend to say is "figure it out yourself" (exact words were: "Think about or research what this part does."), then why reply at all?
A follow-up by "patshak" politely ignores the attitude, and points out that using two or more of these sometimes bulky ferrite cores, let's say on adjacent lines at a power strip or outlet, can cause crowding. Okay... but this only distracts from the original query... "how does a consumer know if ferrite cores are needed?" Are there situations when using them may do more harm than good (as Proffitt implies in another answer).
Perhaps ferrite cores are analogous to vitamin pills... "vitamins" are good (just like suppressing RFI)... but it they are not "one size fits all." Some of us get too much calcium, or iron, for example. I'll bet using ferrite cores, like taking vitamins, can have unintended consequences. If not, why aren't ferrite rings standard on every television power cord?
Still, I cannot find any guidance for consumers on how to determine whether or not to use one or more ferrite cores. Samsung only tells consumers where, not if, the provided cores should be installed, I found no guidance on what the do or how to know if they are optional or always helpful, or only used to address a problem after it has been detected.
Does Samsung provide these ferrite cores as an afterthought, maybe instead of providing a better quality (shielded) power cord? In one CNET forum thread (on ferrite cores), Proffitt writes that ferrite cores protect your "signal" from the effects of a power cord spewing radio frequency interference, but doesn't say how to determine if that is actually happening, or whether ferrite cores will help or hurt in any particular situation. Another of Proffitt's replies (to "patshak") seemed to suggest using ferrite cores on an antenna cable could harm your signal quality.
If I use the three ferrite cores supplied by Samsung with my plasma television (to suppress RFI?), could they also improve or degrade the quality or quantity of power, or the signal quality delivered by any input line to my television?
As an "electronics technician," I make a pretty good biologist (I am out of my field here). I suspect I am not the only one who would appreciate it if some helpful techie would explain the what, why, when and when not, and why not of using ferrite cores. Simply providing a link to a site that explains this would be fine. Won't someone who aced electrical engineering 101 give us non-techies a little guidance?