RF Stoppers (1 Viewer)

AudioQuest RF Stoppers have an internal diameter of 10 mm.
They add 245 ohms of impedance at 1 MHz, greatly reducing RF interference.

Very f****** informative!
These ferrite materials come in a variety of configurations: beads, cores, split, bars, etc. and in a variety of internal diameters.
If you need additional impedence you can do one of two things. If you're using the split ones and you add a second one, the impedances become additive. If you're using a core, and you loop the wire through it, the impedance is increased by the number of turns squared. If you're investigating whether the power cord is a source, then you'd be looking to get a big ass core and loop the cord several times.
Ferrites are typically given 'numbers' that indicate the 'mix' and what their performance characteristics are.
#43 used for when your signals are in the 0.01 to 1 mHz range. Once you go above those frequencies, it starts choking or attenuating the signals. It's generally considered effective in attenuating frequencies from 1 to 1000 mHz. It's a general use material, probably the one that AudioAdvisor is selling.
#61 will attenuate signals 100-2000 MHz. It'd be considered if your signals happened to be in the 0.2 to 10 mHz regiion.
#72 or #73 mix are used if your signals happen to be in the 0.001-1 mHz region
#77 will attenuate signals 5-100 MHz
There's a ton of ferrite mixes out there designed to solve particular problems. Their degree of attenuation, the maximum frequency that they'll attenuate, the broadness or "Q" (like in parametric equalizers), are various parameters that can be manipulated by the manufacturer.
In a generals sense, when you purchase the beads you've got to specify the physical size and the mix (those numbers given above). For example:
FB 23 and FB 63 have 0.2" holes
FB 56 has a 0.25" holes and it'd be used for RG58 or 59 coax.
FB 124 has a 0.5" hole and would work for larger cable like RG 8.
It doesn't matter if the ferrite is bigger than the cable and hangs loosely but then it doesn't give that 'finished' look.
If you don't like RS, there are several online places, even ebay, where you can pick these up. For example.
AllElectronics

You could, if you wanted to try, putting one around the coax going to your TV. That'd address any RFI issues, if there were any, with respect to the outer shield. However, most problems with regards to TV's have more to do with improper or non existent grounding of the cable shield which can, under certain circumstances, have flowing common mode currents. Possible approaches here would be to ground the shield to the ground on the outlet that serves the TV.
F Connectors, especially those installed by consumers, can be problematical. They can provide common path for RFI if the connections are not tight or if the connector is not cripmed or screwed onto the coax tightly enough, or if it is completely missing and the center conductor is just
stuck into the female connector!

There is some info on RFI in the FCC's Interference Handbook (which is free if you ask for them at 888-CALL-FCC), or it used to be.

For additional information you might want to consider contacting http://www.arrl.org/ which is an amateur radio site. Very bright people with practical answers to practical problems.

I'll leave to somebody else to give an email over to AudioAdvisor and see if they'll indicate what mix their using. Wouldn't surprise me though if they either don't know or use the old special and proprietary reply.

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