Re: [RFI] LED lighting

[Gedas <w8bya@mchsi.com>]

Roger, not sure what you were using for a detection system but most 
double walled shielded enclosures (i.e., Lindgren etc) provide around 
120-140 dB S.E. to E-fields.  Less as they got older.  If you had a 10W 
RF source outside of the enclosure (call it +40 dBm) you would have 
roughly a -100 dBm signal inside, which even a mediocre detection system 
or S.A. could easily detect. Like yourself, I used to live inside 
various shielded enclosures and buildings from different manufactures 
for a living as I was a tempest engineer for over 30 years.
Gedas, W8BYA

Gallery at http://w8bya.com
Light travels faster than sound....
This is why some people appear bright until you hear them speak.

On 7/28/2015 10:35 PM, Roger (K8RI) wrote:
> I worked in a double walled screen room quite often. All leads were 
> filtered. The door used a cam to finish closing.  A 10W signal outside 
> the door was not detectable inside.  You could watch the signal go 
> down as the cam was closed.  Well before the cam was closed the signal 
> was gone.  I can't imagine needing more than a standard screen room 
> for measuring RFI from LEDs and their switching supplies.
> In my case the screen room was for isolation of very sensitive 
> measurements in an area with a lot of RF. OTOH  I did a lot of RF 
> monitoring to make sure those 200 KW and up, induction heating units 
> could not be heard.
> 73
>
> Roger (K8RI)
>
> On 7/27/2015 11:25 AM, Hare, Ed W1RFI wrote:
> > Actually, we don't.  We have the screen room to do receiver and 
> > transmitter testing, and a room set up in compliance with ANSI C63.4 
> > to do conducted-emission measurements, but not an anechoic chamber. 
> > Outdoor testing should suffice, being a good approximation to a 
> > calibrated open-area test site.  If we find devices a few dB above 
> > the limits, we don't file complaints, but the things we have found to 
> > be bad have been WAY above the limits, so close enough is close enough.
> >
> > Ed Hare, W1RFI
> > ARRL Laboratory Manager
> > 225 Main St.
> > Newington, CT 06111
> > Tel: (860) 594-0318
> > Fax: (860) 594-0259
> > Email: W1RFI@arrl.org
> > Member: IEEE Connecticut Section
> > Member: IEEE EMC Society, Board of Directors
> > Member: IEEE EMC Society Standards Development and Education Committee
> > Primary representative:  ANSI ASC C63 EMC Committee, Vice Chair 
> > Subcommittee 5 (Immunity)
> > Member: QRP Amateur Radio Club International, Board of Directors
> >
> >
> >
> > From: David Robbins [mailto:k1ttt@verizon.net]
> > Sent: Monday, July 27, 2015 11:19 AM
> > To: Hare, Ed W1RFI
> > Cc: rfi@contesting.com
> > Subject: Re: Re: [RFI] LED lighting
> >
> > what?  you don't have an anechoic shielded chamber to do that kind of 
> > stuff???
> >
> > Jul 27, 2015 11:05:16 AM, w1rfi@arrl.org<mailto:w1rfi@arrl.org> wrote:
> > I bought one multi-LED bulb that came from China. It was dead quiet. 
> > My guess is that it simply put the LEDs in series and connected them 
> > to the line. Not all of them will have a switcher in them.
> > ARRL tested a number and found them to be below the conducted 
> > emissions limits. I want to test them above 30 MHz too, for radiated 
> > emissions, though we'd need to set up outdoors to prevent scatters 
> > from throwing off the readings.
> >
> > Ed Hare, W1RFI
> > ARRL Laboratory Manager
> > 225 Main St.
> > Newington, CT 06111
> > Tel: (860) 594-0318
> > Fax: (860) 594-0259
> > Email: W1RFI@arrl.org<mailto:W1RFI@arrl.org>
> > Member: IEEE Connecticut Section
> > Member: IEEE EMC Society, Board of Directors
> > Member: IEEE EMC Society Standards Development and Education Committee
> > Primary representative: ANSI ASC C63 EMC Committee, Vice Chair 
> > Subcommittee 5 (Immunity)
> > Member: QRP Amateur Radio Club International, Board of Directors
> >
> >
> >
> > -----Original Message-----
> > From: RFI [mailto:rfi-bounces@contesting.com] On Behalf Of David Robbins
> > Sent: Sunday, July 26, 2015 11:37 AM
> > To: 'Phil Snyder'; rfi@contesting.com<mailto:rfi@contesting.com>
> > Subject: Re: [RFI] LED lighting
> >
> > They could just be led bulbs in a standard 120v socket also... in 
> > those there is a switching supply in the base of each bulb.
> > David Robbins K1TTT
> > e-mail: mailto:k1ttt@arrl.net
> > web: http://wiki.k1ttt.net
> > AR-Cluster node: 145.69MHz or telnet://k1ttt.net
> >
> >
> > -----Original Message-----
> > From: RFI [mailto:rfi-bounces@contesting.com] On Behalf Of Phil Snyder
> > Sent: Sunday, July 26, 2015 14:51
> > To: rfi@contesting.com<mailto:rfi@contesting.com>
> > Subject: [RFI] LED lighting
> >
> > Well after a 4 year period the local electric company found the 
> > offending lightning arrester and voila no more noise! Unfortunately, 
> > the neighbor behind me just remodeled the outside of their house and 
> > in the process added about 6 LED lighting fixtures in the soffit 
> > across the front and after a few days of watching and listening it 
> > appears that they are causing way more RFI then the faulty arrester 
> > ever did.
> > I am hoping to learn a little more here before approaching them to 
> > make sure all my facts are straight. I am assuming that there is a 
> > switching power supply running the lights and that the power is cut 
> > to the supply when they are not on since the noise is gone when they 
> > are off. Is it possible to try and suppress the noise on the leads 
> > coming out of the power supply? Does he need to contact the 
> > manufacturer to replace the supply? Unfortunately they are mounted 
> > into the soffit like a can type light you would have inside your 
> > house and I hope the power supply is accessible.
> > Thanks
> > Phil
> > N9LAH
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