[RFI] Low voltage lighting solid state "transformers" (long, somewhat OT)

Steven Farmer wa5rpf at gmail.com
Thu Dec 21 21:29:20 EST 2006

I received the following from Mike Gruber at  ARRL HQ and received his 
permission to re-post it here.


The rules regarding this sort of thing can be a bit confusing.  Any
device that generates a signal 9 kHz or greater as part of its normal
operation, and does not intentionally radiate that signal, is classified
as an "unintentional emitter" under Part 15.  Assuming the device in
question is an unintentional emitter, it would need some type of FCC

An unintentional emitter such as a switching mode power supply typically
undergoes a process called "verification."  This is a self-approval
process where the manufacturer performs the necessary tests and
determines that the device complies with the rules. It is not necessary
for the manufacturer of a verified device to notify the FCC or to send
them test data.  (Note:  There are also several other processes for
different types of devices, etc.)

Under the verification process, there would be no test data or other
record on file at the FCC.  However, a sticker would be required to be
put on the device.  (One exception is a small device.  The FCC
information can be put in the device manual if it is too small to have a

So - assuming the device in question is an unintentional emitter, does
not have an FCC label on it, and does not have FCC information in its
manual; it would appear to be an illegal device.  Furthermore, if the
manufacturer did not know enough to put a sticker on the device, it
would seem highly suspect in terms of meeting other FCC requirements.
It may not meet absolute conducted emission requirements for example,
which are specified under 30 MHz.

If you would like to send a sample to us, we could test it for conducted
emissions here in the Lab.

Mike Gruber, W1MG

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