I have one CFL at the moment which gives the same pattern on 24kHz.
Over the years I have had all makes play up, one decided to wipe out
10MHz, that was due to a dry joint on a suppression capacitor. Dry
joints have also caused other interference and total failure. I
have dismantled several CFL's, poor soldered joints are rife in
them, some components can often be pulled dry from the PCB.
Some designs are a nice source of a VLF ring core, material / type
unknown, I have used them for coupling on two 500kHz / 136kHz multi
turn RX Loops.
As for filament lamps, there is always the classic 'candle bulb
effect' which wipes out analogue TV, I did have the pleasure of
finding one of those in a customers house once.
Eddie G3ZJO
On 01/03/2011 19:13, Mike Dennison wrote:
Today I noticed QRM on 136kHz that started when my wife switched a
light on in our spare room. It had a low energy bulb by Status, and
was marked "11W, 220-240V, 50/60Hz, 100mA". It is described on their
web site as "stick type" and is bayonet fitting. The QRM consisted of
rapidly changing noise sweeping back and forth across the band (see
attached pic).
I replaced it with a Philips Genie WW287 light which did not seem to
generate any noise.
The other low energy lights in the house are General Electric E27-ES
11W bulb types which are very slow to get to full brightness, but are
low QRM at LF. The rest are ancient filament types which are
completely QRM-free of course.
So if you have this noise, perhaps it's one of your light bulbs.
Mike, G3XDV
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