Can someone recommend a ferrite bead for composite video input purposes? I can find beads that have ~75R impedence at 9MHz (which would be a 3dB loss into the 75R termination) but I don't know if I should stay far, far away from that corner with a bead.
I've looked at some consumer electronics and most seem to use a bead of some kind but of course it's hard to know its properties without pulling it out and applying a VNA.
ISTR that LT spice has a whole pile of Wurth ferrites in the libraries
martin
I've seen no visible picture degradation using low pass filters in the
8-10MHz area. Had a DVR video interference problem the other week. Turned out the DVR was mixing down ~13Mhz noise peaks on the incoming composite signals. Crap DVR. Sorted using external lowpass filters. So yes, filtering somehow at lowish frequencies may be advisable.
Is this something we should emulate? I've not used lossy beads in my video-processing designs, and I don't recall seeing them used that way in professional video inputs. What's the story? If a low-pass filter is required for some reason, let it be a real properly-designed filter.
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