[Milsurplus] Redux on LED Lamps- so far

[J. Forster]

Thanks for all the info, even though much of it is discouraging.

I was amused by N2LXM’s report that installing CFLs in the light fixtures
of a building his club was rehabbing “drowned out the HF spectrum.”  Also
that the switching supply for their desk lamps was noisy.  All consistent
with my expectations.

I was sorry to hear that his town’s LED street lights "drown out all FM
stations on my car radio when I drives by at night,” and “All I hear is a
loud roar until I get a half a block off of the road.”

It a good bet that these lights are noisy at HF as well as at VHF.

The Town of Watertown has replaced many of its high-pressure sodium street
lights with LEDs, and I have wondered about the noise they make, but I
have not yet had an opportunity to observe.

Similarly, I was sorry to hear that the LED lamps in traffic signals in
KA2IVY’s area are RF-noisy.


It was nice of W2HX to forward the FCC Part 15 certification of an LED
lamp.  I have not yet read this document.  Unfortunately in my experience
these documents have not been meaningful for HF noise, because the FCC’s
standards are extremely crude and lax and because the level of RF noise
radiated or coupled by induction to a receiving antenna depends on
external factors that aren’t tested.

The URL <http://www.ledbenchmark.com/faq/LED-interference-issues.html>
forwarded by David Hess and by Mikhael Brown was very informative and also
showed that the power spectral density of noise emitted slightly below 30
MHz (as far as the graphs showed) is as great as above 30 MHz.

Sean Kelly did not say whether the deathly silent ballast for his kitchen
fluorescent tubes is an electronic switcher or an iron-core
(auto)transformer/inductor.  My iron-core ballasts are silent, too.  But
the electronic switchers I’ve seen are terribly noisy.  Recently I
augmented my cache of iron-core ballasts with what I hope will be a
ten-year supply.


Sadly, few people know or care about RF noise, so things are guaranteed to
get worse.


Via John

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