[AMRadio] "Magic" lamp QRM

[John Beasley]

Don,

    My brother (KAØVEL) has two of those touch lamps.  He bought them
over 15 years ago and I am surprised they are still sold.  We just figured
they had SCR's in them.  We never tried to suppress the noise, it was
easier just to shut them off.  We experienced similar noise from the little
remote control modules too.

John

----- Original Message -----
From: "Donald Chester" <k4kyv at hotmail.com>
To: <amradio at mailman.qth.net>
Sent: Saturday, October 05, 2002 5:05 PM
Subject: [AMRadio] "Magic" lamp QRM


>
> I recently noticed a very rough, broad signal that wipes out 30-kc
portions
> of the spectrum from the middle of the broadcast
> band through 10 m. It is especially bad on 160 and 80m. I did a little
> sniffing with a portable radio and found the source to be a
> table lamp my daughter just bought. The thing doesn't have a conventional
> switch, but a metal base, and you turn in on and off
> by touching the base with your hand. The thing must have some sort of
> oscillator somewhere in the 450 kc range, and works by
> detuning the oscillator when you touch it. What kind of rubbish is someone
> going to think of next to garbage up the radio
> spectrum!
>
> I have never seen one of these things before. Is this a novelty or
> speciality item, or is this the way all table lamps are made these
> days? (This was probably the first time in over 20 years since anyone here
> brought home a new table lamp.) Surely, this must fall under Part 15, so I
> wonder why the FCC even allows those things to be sold on the market. The
> noise is far worse than the hash from my computer monitor, and I thought
> that was already bad enough. I'm surprised the AM broadcast industry isn't
> raising bloody hell about stuff like this. I can't imagine polluting the
rf
> spectrum with rubbish because someone might be too lazy to flip a switch
on
> a table lamp.
>
> I'm wondering if anyone else has had problems with interference from those
> things, and what might be the simplest solution. I tried an in-line rf
> filter, but it made no improvement whatever. Unless there is something
> simple to by-pass, the only solution I can think of is to go into the
thing,
> rip out the electronics, and mount a conventional swith with a knob on the
> base. I'd like to hear form anyone who has successfully fixed one of these
> things some way other than clip-leading the power cord across the HV
> terminals of the plate transformer and throwing the big switch.
>
> Don K4KYV
>
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