I believe CKC lab (if I remember correctly) near Yosmite has facilities
(OATS) with large turntables which can and do accommodate complete rail
cars. But Detroit is closer to you.
Road trip to a beautiful area (but over crowded)???
Dave - WØLEV
On Sun, Dec 25, 2022 at 11:32 PM Hare, Ed, W1RFI <w1rfi@arrl.org> wrote:
> The only way to test a solar system is on an OATS, although the chambers
> at GM in Detroit would probably be big enough. The interference reports we
> are seeing are all on HF, unless we have a smattering of reports on VHF,
> and, from all indications of the system we were able to probe closely, the
> AC mains are not the primary radiating element on HF, so it is our belief
> that the system meets the FCC emissions limits.
>
> In the long run, in response to changes in technology, I think that FCC
> will need to specify conducted limits for secondary wiring, too, but even
> if an NPRM were to come out tomorrow, 10 years would probably be a
> realistic time frame in which to expect a decision.
>
> IMHO, we are better off gathering the industry to create a Recommended
> Practice that sets "voluntary" limits, defines good installation practices,
> provides an Annex to provide information for consumers and outlines
> appropriate complaint responses. By my guess, building on (subtracting,
> actually) what was accomplished for the electric-utility industry, this
> could be in IEEE ballot within 3 years.
> ------------------------------
> *From:* David Eckhardt <davearea51a@gmail.com>
> *Sent:* Sunday, December 25, 2022 6:11 PM
> *To:* Hare, Ed, W1RFI <w1rfi@arrl.org>
> *Cc:* Henry Pfizenmayer <pfizenmayer@q.com>; rfi@contesting.com <
> rfi@contesting.com>
> *Subject:* Re: [RFI] : Solar Panerl RFI / noise in sync with music
>
> Thanks for relating, Ed. And you (et.al) should wonder why I see a
> crying need to revisit limits, measurement philosophies, and even C63.4.
> But it won't happen in my lifetime as I just turned 76 (pray for a flip of
> the magnetic poles of the earth????).
>
> I've always tested to "as typically installed or used by the consumer".
> We all know resistors are (ideally) non-reactive and convert electric
> energy to heat (and some infrared electromagnetic radiation, but that's for
> the safety guys). Not so with speaker "antenna" wires.
>
> And the real problem with solar power is how do you satisfy that
> requirement in a typical 10-meter Semi Anechoic Chamber? With all the
> connecting wiring, it doesn't fit on the turntable. Man, I still favor
> OATS in a nice quiet valley in the Rockies. We used to have just such an
> installation, but the guy lost his accreditation due to not keeping up with
> the paperwork.
>
> Dave - WØLEV
>
>
>
> On Sun, Dec 25, 2022 at 9:14 PM Hare, Ed, W1RFI <w1rfi@arrl.org> wrote:
>
> The one i have experience was a Class D amp intended to be wall mounted
> and connected to with bluetooth. A ham with a very sensitive setup was
> hearing it 1700 feet away. Yikes!
>
> Now, here's the interesting story that I need to find time to document so
> I can present it at a future IEEE EMC Symposium, or at least publish it as
> a peer-reviewed article. It really points out a problem that could impact
> future standardization.
>
> So, I bought one of the Class D amps in question. I terminated its speaker
> outputs in 15 ohms and I tested its conducted emissions in "standby" and
> powered on. It measured about 10 dB below the Part 15 Class B limits. What
> the actual heck is going on? There is no way the conducted emissions could
> be heard that far away, so I explored farther. I connected a signal
> generator to it and cranked it up. Conducted emissions increased slightly,
> but not to the point where I believed this to be the radiated problem.
>
> So, I assumed that the speaker leads were the radiators, so I took off the
> 8-ohm resistors and put them at the end of 16-foot speaker wires, zip type,
> untwisted, to be a reasonable worst case. I brought out the EMCO loop
> antenna and put it about 10 meters away. (Yes, this was in the Lab, so
> scatterers galore, but I was looking for gross problems. Yup, it was
> loud. So I then put an L/C filter in the speaker lead and a ferrrite
> choke. It was STILL pretty loud. I then happened to look at the conducted
> emissions. The CONDUCTED emissions were about 20 dB or more higher.
>
> It turns out that the coupling from the common-mode currents put on the
> speaker leads to nearby conductors unbalanced the conducted emissions,
> creating a substantial common-mode current that changed conducted
> emissions. So, when tested in a Lab with 8-ohm resistive terminations on
> the speaker lead, the unit "passed," but when used in its normal fashion,
> with real speakers, it did not.
>
> I had remembered years back we were testing an LED bulb that just passed
> Part 15B, when I went to unscrew it, the conducted emissions rose quite a
> bit. Well, I knew that there is no way FCC would consider that to be
> actionable, so I forgot about it and did the rest of my tests. But the
> incident with the Class D amp piqued my curiousity, so i got out some
> spotlight LED bulbs that were near the limit and tested them again. Sure
> enough, putting my hand near them caused conducted emissions to rise.
> Interesting, but still not actionable.
>
> My test fixture was a simple ceramic socket, placed in a C63.4 compliant
> room. I then purchased on of the "cans" that most spotlight bulbs are
> installed in, and grounded it to the room ground plane. The conducted
> emissions increased by 8 dB simply by using the bulb in a way that it is
> very likely to be used. To me, this speaks loudly to the need to make
> revisions to the test standards, which simply measure the bulb pretty much
> the way I did.
>
> There is plenty of work to keep me busy for the rest of my life! 🙂
>
> Ed Hare, W1RFI
> ARRL Lab
>
>
>
>
>
> ------------------------------
> *From:* RFI <rfi-bounces+w1rfi=arrl.org@contesting.com> on behalf of
> David Eckhardt <davearea51a@gmail.com>
> *Sent:* Sunday, December 25, 2022 3:22 PM
> *To:* Henry Pfizenmayer <pfizenmayer@q.com>
> *Cc:* rfi@contesting.com <rfi@contesting.com>
> *Subject:* Re: [RFI] : Solar Panerl RFI / noise in sync with music
>
> It likely was a Class-E amp (or worse). They can be dirty as $%^& when
> stressed (by the strong bass notes).
>
> I once tested a Class-E home automation system with all kinds of Class-E
> amps (for intercoms and distribution of music from a number of sources).
> It was the ONLY product in 35+ years we had to install an 20 dB attenuator
> in series with the input to the R&S conducted emissions receiver!
>
> Dave - WØLEV
>
> On Sun, Dec 25, 2022 at 8:09 PM Henry Pfizenmayer via RFI <
> rfi@contesting.com> wrote:
>
> > Mike et al ---If that was not tongue in cheek as they say -- this last
> > summer I started getting thumps of
> >
> > noise on 6 meters -and was far worse at 25 mhz -- Then I noticed it was
> > in sync with neighbors outside
> >
> > speakers thumping out a strong bass line. I went out with my IcomR10
> rx
> > and loop -
> > and yep that was the source. The amp was obviously going into oscillation
> > in sync with the loud bass notes .
> > No use talking to that guy - so I just prayed the damn amp would fry
> > itself . Prayers were answered
> >
> > in just a hour or so and noise never re-appeared.
> >
> >
> >
> > 73 Hank K7HP
> >
> >
> >
> >
> >
> >
> >
> >
> >
> > Message: 1
> > Date: Sun, 25 Dec 2022 11:51:20 -0500
> > From: Michael Martin <mike@rfiservices.com>
> > To: "Dave (NK7Z)" <dave@nk7z.net>
> > Cc: Rfi List <rfi@contesting.com>
> > Subject: Re: [RFI] Another Solar Panel RFI System
> > Message-ID:
> > <CAPZkRSEvyTNyLcJT-3e1gNnkTP+WNX15DFXUXHpqf5YZa67YEw@mail.gmail.com>
> > Content-Type: text/plain; charset="UTF-8"
> >
> > I'm trying to capture a noise with the intermittency rhythm in sync with
> > Christmas music
> >
> > Michael Martin
> > RFI Services
> > 51 W Bay Front Rd
> > Lothian, MD 20711
> >
> > 240-508-3760
> > mike@rfiservices.com
> > [http://www.rfiservices.com<]www.rfiservices.com<
> > https://webmail.centurylink.net/app/www.rfiservices.com>
> > _______________________________________________
> > RFI mailing list
> > RFI@contesting.com
> > http://lists.contesting.com/mailman/listinfo/rfi
> >
>
>
> --
> *Dave - WØLEV*
> _______________________________________________
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> http://lists.contesting.com/mailman/listinfo/rfi
>
>
>
> --
> *Dave - WØLEV*
>
>
>
--
*Dave - WØLEV*
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