Luminosity of CFLs and H-Line
andrew....@googlemail.com
This might be of interest….
For those that don’t like ChatGPT, please don’t shoot the messenger – just correct the errors on this list instead!
Andy
Adrian
Neon and fluorescent lights are another potential source of radio interference. Radar units tend to be affected not only by devices operating at or near their assigned frequencies, but also by devices operating at multiples of that frequency. For instance, a fluorescent lamp operating at 60 cycles/sec will generate a speed reading of around 20-40 MPH on an radar unit. Officers can avoid this by parking their patrol units well away from illuminated areas, and again, by carefully listening to the tone.
from https://policeradarrepair.com/ghost-readings-and-elimination-of-radar-effect/
Bruce Randall
The small CFL bulbs are interesting. They convert the line voltage to DC then filter with a capacitor. This runs a switch mode power supply (SMPS) usually in the range of 100 kHz to 200 kHz. This is stepped up to a high enough voltage to start the arc in the mercury vapor. The mercury vapor is at a very high temperature, as much as 10,000 K. Because of the low pressure inside, not enough heat escapes to damage the glass. Because of the high temperature it generates noise into the microwave region.
The IBT at 10 GHz and scope in a box at 1420 MHz can easily see CFL noise. I use a plastic work light with a CFL as a crude signal source on both of these. Note that a metal shield work light blocked this noise. Moving the CFL work light around a small dish at a meter or so spacing can actually give you a feel for side lobes and back radiation in the antenna pattern. It is a useful, but crude signal generator! This noise source is noticeable at 10 meters away in the main beam of the IBT.
The SMPS in CFL or LED lights generate RF strong noise in the 100 kHz to 200 MHz area. SMPS Noise drops off rapidly above 200 MHz. They have very little RF noise above that.
I spent a good part of my work life in RFI test labs. SMPS noise always needed filtering to be legal for FCC 15. Problems from a few MHz to 1500 MHz were common for digital circuits. DRAM clocks are the worst headaches. One SMPS had to meet Mil standard 461. That power supply had more RFI filter than SMPS parts in it.
Another note. Passes FCC 15 or CE equivalent says it is not likely to interfere with consumer electronics. Radio telescopes and amateur radio receivers are far more sensitive and often plagued by RFI from "passes FCC 15" devices.
Bruce Randall NT4RT
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andrew....@googlemail.com
My apologies to anyone who might have tried to look at my original link that I posted in this thread (Luminosity of CFLs and H-Line) today, but a server meltdown has irrecoverably wiped anything I added to my website in last 48 hours……probably that is a bonus to the amateur radio astronomy community, really!
For anyone who is bored, and looking to be even more bored, my website (www.astronomy.me.uk) is now over 80 GB in size – plenty there to send you to sleep – better than counting sheep! Feel free to comment on anything you might find there on line or via my contact me page.
Andy
To view this discussion visit https://groups.google.com/d/msgid/sara-list/777f0cbd-a5c3-40c4-bd55-73a349101cba%40gmail.com.