My son brought home a wireless charger for his Apple phone the other day. A generic model from Argos, I grumbled that it probably produces a load of RFI.
Does it?
A quick hook-up this morning shows that, yes, it produces pulsed RFI on 28MHz (it's likely the same or worse on other bands). It's fairly low level when the charger base is just on and sitting there, but bringing my hand in close proximity to it produced a big increase in noise, as you would expect from the capacitive coupling. It might produce continuous RFI when a phone is lying on it and charging is underway, but I haven't checked that yet.
The good news is that, with the addition of a substantial Type 31 split ferrite with at least two, close-fitting windings of the supply cable, the RFI was removed pretty much completely.
Of course, it's a lot easier, cheaper and lower RFI simply to use a cable!
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| Type 31 ferrite pretty much eliminates the problem. |
