An additional article can be seen at:
http://www.arrl.org/tis/info/pdf/59378.pdf
73 from ARRL HQ,
Ed Hare, W1RFI
ARRL Lab
225 Main St
Newington, CT 06111
860-594-0318
w1rfi@arrl.org
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> -----Original Message-----
> From: EDWARDS, EDDIE J [mailto:eedwards@oppd.com]
> Sent: Monday, December 27, 1999 2:44 PM
> To: 'kmarch'; rfi@contesting.com
> Subject: RE: [RFI] Noise
>
>
>
>
>
> > -----Original Message-----
> > From: kmarch [SMTP:kmarch@ix.netcom.com]
> > Can someone tell me how to reduce or elimate noise caused by SCR
> > controlled
> > lamps? Tnx, Bob
> >
> [Ed-K0iL] Those darned Touch Controlled lamps!
> Here's some info from the ARRL TS info server on these "Made in
> Taiwain" lamps. Check the RFI list archives at contesting.com for my
> personal story on how I got a new neighbor to get rid of his lamp by
> "haunting" it.
>
> 73,
> de ed -K0iL
>
>
> File: RFILAMPS.TXT
> Updated: November 17, 1995
>
> ARRL RF Touch Lamps and Dimmers Information Package
>
> TOUCH LAMPS
>
> RF Touch lamps are RF-operated devices that often cause, or are
> susceptible to, EMI problems. They have a free running oscillator
> that is very broad and rich in harmonic energy. This oscillator is
> hooked up to a touch plate that changes the frequency of the
> oscillator
> when a hand is placed near the plate. Unfortunately, this plate also
> acts as an antenna, radiating some of the energy of the
> oscillator, or
> picking up nearby radio signals. When the former happens, it
> can interfere
> with other services. When the latter happens, the circuitry
> inside the
> lamp reacts the same way that it would when the plate is
> touched -- the
> lamp changes states from "off" to "on".
>
> Although cases of moderate interference can sometimes be
> cured by
> using a "brute-force" type AC-line filter and/or a
> common-mode choke (see
> the ARRL Book, Radio Frequency Interference -- How to Find
> It and Fix It
> for more information about AC-line filters and common-mode
> chokes) most
> cases will require internal modification to the lamp. For a
> number of
> different reasons (you may be blamed if anything EVER goes wrong with
> the lamp or house wiring) you do not want to perform this
> modification
> on equipment that is not your own. Remember -- house AC
> power is dangerous.
>
> These modifications must only be performed by qualified
> service personnel!
>
> Here are some reprints from QST "Hints and Kinks":
>
> RFI and Touch-Controlled Lamps.
> I have found a simple cure for those touch-controlled
> lamps that turn
> themselves on and off during nearby radio transmissions. In my case,
> 40-meter operation gave the most trouble, with 75-meter
> operation a close
> second. Higher frequencies presented no problem. (I use a
> ground-mounted
> vertical antenna for 80, 40 and 15 meters, and the lamp is
> approximately
> 150 feet from the antenna. An AC-line filter at the lamp did
> not eliminate
> the problem.)
>
> A 1k ohm resistor (in series with the signal input lead to the
> encapsulated circuit that operates the lamp) cured the
> problem for me. I
> suppose the required resistor value would vary with the
> RF-field intensity
> and frequency.
> -- John M. Adams, W7OTC, Sun City, CA
>
> More on RFI to Touch-Controlled Lamps.
> I had the same problems as W7OTC with a touch-controlled
> lamp switched
> on and off by my transmissions (100 W to a roof-mounted
> vertical, with two
> radials per band). The problem occurred during operation on
> the 80- through
>
> 15-m bands, but 10-m operation had no effect. A 1-k ohm
> resistor was not a
> complete cure in my case.
>
> A 3.3k ohm resistor in series with the signal input on the lamp
> helped on all bands except 80m (an additional 1.8k ohm
> prevented the lamp
> from functioning). When the resistor was replaced with an RF choke
> (100 uH, 139 mA), the problem abated on all bands except for 80 m.
> On 80 m, the interfering signal was considerably attenuated
> by the choke,
> but the lamp still switched. The choke alone may be enough
> to clear up
> the problem in some cases.
>
> The final answer turned out to be both the RF choke and
> a 1.8k ohm
> resistor in series with the signal-input lead to the
> touch-control circuit.
> -- Colin Hall, G4JPZ/W6, Marina Del Rey, CA
>
> Touch-Lamp Transceiver.
> When my wife told me she had bought a three-way lamp
> that switched on
> and off at the touch of any of its metallic parts, I did not
> realize she
> had purchased a transceiver. I found that my transmitted
> signal would
> cause the lamp to operate exactly as if I had touched its
> metal parts.
> Later I discovered a raspy, S8 signal at 1875 kHz -- it was
> coming from
> the lamp, which was located three rooms away on a different
> AC circuit.
> The lamp signal is present from 40 meters down. At
> frequencies from 20
> meters up, my operation is undisturbed.
>
> A box inside the lamp contains a circuit board through which AC
> line voltage is routed and which has a wire connected to the
> metal base
> of the lamp. When the lamp is plugged in, the lamp signal is present
> at all times, regardless of whether the lamp is on or off.
> In my attempts
> to eliminate the interference, I tried a commercial AC
> filter, coiling the
> lamp cord on some ferrite material and other such approaches without
> success.
>
> To make sure the lamp my wife had was not defective, I
> borrowed a
> similar lamp from a neighbor to try it. I found it to
> perform in exactly
> the same manner except that the frequency of oscillation was somewhat
> different. There is no manufacturer or distributor name on
> the lamp or
> packing container. The lamp was made in Taiwan.
>
> I am writing so that others who may be experiencing similar
> difficulties may have some idea of the probable source of
> interference.
> After I described what I discovered to a ham friend, he realized that
> such a unit had been causing interference to his station for
> more than a
> month.
> -- Cal Enix, W8EN, 209 S Kalamazoo St, White Pigeon, MI 49099
>
> If these cures don't work, it may be possible to shield
> the electronic
> switch module, but this must be done safely! You may also
> want to contact
> the manufacturer and send a report of your problem to ARRL
> Headquarters
> RFI Desk, 225 Main St. Newington CT 06111.
>
>
> DIMMERS
>
> Light-dimmer Interference Reduction.
> Radio Amateurs who've have been cursed with RFI from
> solid-state light
> dimmers will be interested to know that at least one domestic
> manufacturer -
> Lutron - produces light dimmers that incorporate RFI
> suppression techniques.
>
> The Lutron NOVA series uses toroidal chokes that provide a
> significant level
>
> of RFI suppression.
>
> I bought a Lutron model N-600, which will handle up to
> 600 watts of
> incandescent lighting. Temporarily installed in my radio
> shack, a generic
> light dimmer produced an S9+ reading at 230 kHz (an arbitrary noisy
> frequency). The N-600 produced a reading of S3, a difference
> of about 40
> dB.
> Admittedly, this is not zero, but installing the N-600 some
> distance away
> provided a reduction in RFI that is very gratifying. Indeed,
> I new hear new
>
> noise sources, heretofore undetectable through the dimmer din.
>
> You're not likely to find these dimmers at your local
> discount store,
> and they are not inexpensive. Check for the availability of
> these dimmers
> at a lighting fixture store and expect to pay about $25
> apiece for them.
> -- Richard G. Brunner, AA1P, 10 Brookside Dr., Foxboro, MA 02035
>
> Lutron Electronics Co., Inc.
> Suter Rd.
> Box 205
> Coopersburg, PA 18036
> 215-282-3800
>
> If you come up with a better solution for these problem,
> please write
> to the RFI Desk with the solution. It sounds like it would be a good
> candidate for Hints and Kinks!
>
> "73" from ARRL HQ
>
>
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>
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