Use of ferrite beads / core on screened cables

[Henry8]

Hi,

I have some ferrites, 10mm i/d, 14mm o/d, 20mm long.
A screened cable can easily pass thru it, or i can loop it one time.
Some tests i did showed it did not help with hum pickup (cable near a txmfr)
Is there any benefit to using one?

 

[sesebe]

Hi,
It will help only at very high frequency (10's-100MHz)

 

[DF96]

It might stop interference from your mobile phone, the broadcast transmitter a few miles away, the CFL a few feet away, and the radio amateur or taxi firm just over the road.