w4atk at bellsouth.net
Fri Nov 21 06:57:44 EST 2008
This type of noise is characteristic of a Chinese made switching
battery charger. I will just bet one of the neighborhood kids has a
Chinese made electric scooter. The charger is 36V and very bad news.
The frequency will change as the battery charges, but will always be a
consistent 56KHz. A lot of people will confuse this with the refresh
rate on some monitors. I can supply photos of the offending charger and
scooter if you would like. I have one two doors up the street from me.
ICE makes a filter than will go a long way toward clearing it up,
but it is expensive. I have worked out an arrangement with the owners
that stipulates that the charger will only be used when there is
expected use of the scooter. Alas, they forget and leave it plugged up
and eventually I will have to call.
If I can be of further assistance, drop me an email.
73s Jim, W4ATK
More information about the RFI