[aprssig] APRS: RFI from LED bulbs?
noskosteve at yahoo.com
Mon Oct 22 16:43:26 EDT 2018
Fun times ahead from Mr Negative here...
I have investigated VHF RFI and before retiring, managed a lab [M] that was responsible for product validation (performance to specs), RFI measurements, EMC (Electromagnetic Compatibility) and UL approval.
I have an 18 W desk lamp that produces more HF RFI when it is OFF than on, yes, OFF. It has a lighted-touch-button on-off and needs power to light the button and run the button detect.
--> Switch-mode power supply...
The issue with LED bulbs is not whether a bulb meets Part 15, but that there will be [are] hundreds of them in your neighborhoods and all that noise adds up.
Ten bulbs means the noise can be 10 dB above the legal limit !
It's not that simple, but bad none-the-less.
Part 15 has a limit to the amount of interference each can emit. It is not Zero. Also, that is for ONE bulb in some fixture. If you're close enough to one, it can still cause problems.
With many of them in random fixtures, who knows. This has been a gloom-n-doom bad omen since CFLs came out since they also used electronic switching to generate the high start and run voltages
In 08-09 a local VHF repeater suddenly had reduce sensitivity for mobiles at the boundaries of the county. After some weeks of hunting and conferring with the ComEd RFI hunting Field guys, I found it was a bad batch of newly installed lightning arresters in McHenry Illinois. There were 6 on every 5th pole for DUAL 3-phase, 38 kv (I think) Lines. Real sweet.
The power lines when modeled as a long-wire antenna showed a really nice lobe that pretty much pointed right at the repeater up the hill west of town.
They were arcing internally, but had been 100% tested for RFI !!?!!
I visited the manufacturer's factory and we found that their RFI test setup was faulty... Also, their molding machine was cocking the MOV pucks when the external silicone was molded on (they aren't glass, but look like it). Then, the factory RFI test station had somehow gone ka-flouie.
IIR, I talked with Ed back then.
Dozens of these arresters in town were spewing forth, joyfully.
Just like our future for LED bulbs... [sad face emoji]
Regards, Steve K9DCI
Science & Technical Advisor
P.S. A 350 watt DC Brushless blower motor (Pulse Width Modulation switch-mode) I designed in around 1987 would absolutely drive an Am radio off the table without a 5 buck Cornell Dubilier line filter added on.
On Mon, 10/22/18, Hare, Ed W1RFI <w1rfi at arrl.org> wrote:
Subject: Re: [aprssig] APRS: RFI from LED bulbs?
To: "Robert Bruninga" <bruninga at usna.edu>, "aprssig at lists.tapr.org" <aprssig at lists.tapr.org>
Cc: "Gruber, Mike W1MG" <mgruber at arrl.org>
Date: Monday, October 22, 2018, 8:43 AM
The ARRL Lab has the ability to
make quantified measurements of field strength and conducted
emissions from all types of devices. We use calibrated
antennas and spectrum analyzers with CISPR detectors to make
accurate measurements in microvolts/meter. We do not have
an anechoic chamber or calibrated open-area test site, but
our in-situ measurements can give a very good indication of
how these devices would perform if measured under the
laboratory conditions used by manufacturers and regulators
to authorize devices.
are probably literally thousands of LED bulbs made today, so
we can't act on a simple report that "LED bulbs
need to be measured." When they first started coming
out, the ARRL Lab bought a large number of them and measured
them, finding that the ones being sold by the big box stores
at the time complied with the emissions limits.
(Interference is still possible.) That could change,
though, so what we need are model numbers and where they are
being sold. The Lab can then buy a couple of the suspect
devices, test them, and if there is an apparent
emissions-limit violation, ARRL can turn this over to the
FCC as a formal complaint.
Unfortunately, most of the reports we receive
do not provide enough information to act. They can range
from "LED bulbs are noisy" to "my neighbor
had noisy bulbs so we threw them away and replaced them with
specific RFI reports, including model numbers of bulbs if
RFI at arrl.org.
Ed Hare, W1RFI
From: aprssig [mailto:aprssig-bounces at lists.tapr.org]
On Behalf Of Robert Bruninga
October 22, 2018 9:23 AM
To: aprssig at lists.tapr.org
Subject: [aprssig] APRS: RFI from LED bulbs?
I am hearing reports of RFI
from these LED bulbs. Not just HF, but also VHF.
If you can make any quantitative assessments of
such RFI, please let me know.
And the amazing thing is that at VHF you will
never notice it because RFI is noise power and it is noise
power that keeps a squelch CLOSED.
open the squelch and sometimes RFI will show full scale on
the S meter yet not open the squelch. And on my radios,
when the squelch is closed, the S meter is inactive and
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