"m II" wrote in message
news:lS9Ac.48479$Ds.19843@clgrps12...
Dave Holford wrote:

I recently purchased a pack of the small screw-in fluorescent bulbs and
the package contained a statement to the effect that although they had
been approved by the FCC they may cause interference to radios, wireless
networks, remote controllers etc.

A quick check with a portable HF receiver disclosed that they do indeed
radiate wide spectrum noise, although at a low enough level that I have
not noticed a problem when using an outdoor antenna with co-ax feed.

Some years ago there were rules concerning the use of dimmers near
radio telescopes because of the noise. All this stuff is accumulative.

How can any device that causes interference be type approved by UL
or the CSA? There may be some monetary incentives going on that we
aren't aware of.



I can't speak for CSA, but UL doesn't cover RF radiation, only safety issues
and other concerns of insurance companies.

As for the RF noise, FCC Part 15 applies to all such devices. Part 15 rules
allow for really quite a bit of RF garbage (100mW on AMBCB can create quite
a havoc, especially when it's connected to a nice long antenna like your
electrical wiring). I believe all the small fluorescent stuff uses a
switching power supply, similar in function to the one in your computer.
This means square waves.. and square waves mean beaucoup RF radiation up to
who knows how far in the spectrum.