[RFI] More on lamp RFI

tduffy tduffy <tduffy@sygnet.com>
Sat, 02 May 1998 12:31:16 -0400

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May 1998 16:27:06 -0500 From: dale and sue Reply-To: svetanof@mc.net
X-Mailer: Mozilla 3.01C-MCKIT (Win95; U) MIME-Version: 1.0 To: "Juan,
EA5RS" CC: RFI Reflector Subject: Re: [RFI] HF Oscilator driven lighting
lamps References: <199805011149.NAA13280@mx1.landsraad.net>
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7bit Juan, EA5RS wrote: > > I remember reading years ago a note in QST
regarding the launch of a > lighting lamp driven by HF energy. Does
anyone know if this kind of > systems are now widely used? What are the
EMC requirements imposed to > this kind of equipment? > > The reason I'm
asking is because I suspect such a system could be the > source of a
high level interference in my QTH. The noise is a > series of very
narrow impulses at the rate of the power line > freq (50 Hz), covering
from 16 MHz up to 30 MHz (may go up higher, > just don't have a receiver
covering >30 MHz). The noise blanker is > very effective in removing it,
but only when there are no strong > signals on the band. Interference
power at my RX is in the order of > -85 dBm in a 6 KHz bandwidth
anywhere between 16 and 30 MHz on a 3 > el yagi, rendering the station
useless for weak long path signal work > during the night ! There is
little or no noise in the LF/MF car > radio when close to the suspect
system, which is 200m away from the > HF antenna and almost within
line-of-sight, and produces a very > bright white - blue light.
Externally it is a 10cm long tube in a > housing fit with an optical
reflector and a glass window in front, > and there is a box on top where
the AC line enters the housing. > > Can anyone help? > Thanks in
advance, > Juan, EA5RS > Dear Juan: I don't believe the light you
describe is one of those RF driven light bulbs. Here in the States, I
think the ones to which you refer are supposed to operate at about 13.26
MHz. Of course, anything is possible. I don't have any at my QTH. It
would have to meet FCC Part 15 and/or Part 18. I have to assume any such
devices there would need to meet current CE standards for emissions. The
device you describe sounds like an industrial type of lamp, so its
permitted emission levels may be higher than for consumer equipment.
>From your description of the light output color, it sounds more like
you have a metal halide lamp causing the problems. These are a gas
discharge lamp that require a ballast, just like common flourescent
lamps. It is possible that the offending fixture has an electronic
ballast that is malfunctioning (or did not meet CE emission standards).
Is there any way you can take your station receiver closer to the lamp?
Alternatively, maybe you could borrow a portable SW radio that tunes
above 16 MHz. Getting either radio closer to the lamp and observing the
noise level would at least confirm that it is the source. Since halide
lamps are usually used in commercial or industrial applications, you
will then need to see if someone would turn it off, then on, as a final
confirmation. (Note: If it is a halide lamp, it will not re-start
instantly. It may require as long as a minute before operation resumes.)
Best luck. 73, de Dale, WA9ENA

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