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Old April 30th 08, 03:40 AM posted to rec.radio.amateur.homebrew,sci.electronics.design
amdx amdx is offline
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First recorded activity by RadioBanter: Jul 2006
Posts: 349
Default Help, Laptop causes FM interference


"Phil Allison" wrote in message
...

"Charles"


Switch-mode power supplies are dirty ... lots of harmonic energy. The
interference is both radiated and sent back into the ac mains.



** But they don't usually generate energy in the FM broadcast band ( i.e.
88 - 108 MHz) - that is more likely to be due to the CPU and associated
high speed circuits inside the PC.




...... Phil

Good call Phil,
Maybe I didn't say it clearly, but just plugging the ac cord in and
holding
it near the laptop induces noise on the power line. ( ac cord only, no
switching power supply attached)