Actually, testing BPL was easy. For access BPL, ie, on overhead power lines,
the rules said to crank it to the maximum power, then report what power setting
was needed to achieve compliance. In practice, they were tested at the power
setting that achieved compliance, even though the systems didn't actually
manage to communicate data at that setting. The FCC looked at the test results,
the systems complied, so Certification was granted. For the in-premise
systems, there are no power settings, but the systems are Verified, not
Certificated, although in my experience with HomePlug, the in-premise systems
do comply.
Recent rules changes have put even acc
From: David Eckhardt [mailto:davearea51a@gmail.com]
Sent: Monday, February 05, 2018 5:19 PM
To: Hare, Ed W1RFI
Cc: Cortland Richmond; RFI
Subject: Re: [RFI] RFI every 15 KHz on 160 meters, suspect source is a
manufacturing facility.
Yes, tested as a system. Sure...... Yea....... You bet........ And how
on God's green earth did any reputable and accredited lab responsibly test BPL?
There are in-situ tests for regulatory purposes, but they are usually very
tenuous as to real results, especially with the ever increasing RF fog of today.
True, FCC is no longer directly involved in formal regulatory testing.
However, the lab that conducts the testing is certified by one or several
'competent bodies' to do the testing to FCC and/or CE standards and
requirements (NAVLAP and A2LA, to mention two). It is no small exercise to
become accredited for regulatory testing and maintain that accreditation. I've
been on both ends!!! Sad, we had one lab, a very good OATS, here in N.
Colorado that lost their A2LA accreditation due to sloppy paper trails on
equipment calibration. They were my lab of choice. No longer!!
The real problem these days is an FCC who is becoming less and less concerned
about the regulations they have in place (especially Part 15, both Subparts B
and C) and more and more concerned about their own existence and posteriors.
Not to mention the influx of "RF Junk" from China with absolutely no testing or
attention to EMC/RFI other than to make a buck. Where is the FCC in all
this?????!!!!!
Dave - WØLEV
EMC Design & Test, LLC
On Mon, Feb 5, 2018 at 9:55 PM, Hare, Ed W1RFI
<w1rfi@arrl.org<mailto:w1rfi@arrl.org>> wrote:
True, Cortland.
I would take the position that if they are switching synchronously, they are a
system and as such need to be tested as a system. Having said that, we need to
keep in mind that these are Verified under FCC rules, essentially self tested
by the manufacturer, with almost no oversight by the FCC. It is very likely
that an individual unit was tested and if it complies, the Verification was
considered met.
That is an interesting thought that a single switcher might lock up on it is
own, and thus what was intended to be asynchronous would become synchronous.
I'd think, though, that even with modest filtering to meet the rules, the power
supply would not "see" other units. I'd love to see any reports of that
synchronization actually occurring, though.
Ed
-----Original Message-----
From: RFI
[mailto:rfi-bounces@contesting.com<mailto:rfi-bounces@contesting.com>] On
Behalf Of Cortland Richmond
Sent: Monday, February 05, 2018 3:49 PM
To: RFI
Subject: Re: [RFI] RFI every 15 KHz on 160 meters, suspect source is a
manufacturing facility.
And even if each WERE FCC Class A compliant, together, they could -- switching
synchronously -- far exceed the limit. A cheap switcher might lock to noise on
a common power source, whether generated elsewhere or on one or more switchers.
Cortland
KA5S
On 2/5/18 12:09 PM, Hare, Ed W1RFI wrote:
> That system would be a Class A Part-15 device, so would have to meet the
> higher industrial limits. Locally, ie near the motors, controller or wiring,
> I could well imagine a 50+ dB increase in noise from a "legal" device. If
> that were 55 dB at a nearby Amateur antenna, it is possible that the system
> exceeded the Class A limits.
>
> Ed, W1RFI
>
>
>
> -----Original Message-----
> From: RFI
> [mailto:rfi-bounces@contesting.com<mailto:rfi-bounces@contesting.com>] On
> Behalf Of David
> Eckhardt
> Sent: Saturday, February 03, 2018 12:50 PM
> To: Cortland Richmond
> Cc: RFI
> Subject: Re: [RFI] RFI every 15 KHz on 160 meters, suspect source is a
> manufacturing facility.
>
> Look for AC/AC or AC/DC switching converters. I won't relate the story, but
> we had an incident where 208/3-phase was fed to several speed controllers on
> a large irrigation system (20-housepower AC motors). The proper and required
> decoupling components were not bought and installed due to cost. We
> experienced switching noises some 55 dB over baseline on a portable R&S
> spectrum analyzer. Our emissions peaked right in the middle of the 40-meter
> band but were detectable to low VHF. The controllers were from China with a
> storefront on the west coast - what else is new these days with no FCC
> enforcement.
>
> Dave - WØLEV
>
> On Sat, Feb 3, 2018 at 3:36 AM, Cortland Richmond
> <ka5s@earthlink.net<mailto:ka5s@earthlink.net>>
> wrote:
>
>> Great Don.
>>
>>
>> On 2/2/18 8:28 PM, Don Kirk wrote:
>>
>>> Hi Cortland,
>>>
>>> Thanks for the info. I just constructed a 3" diameter loop (not
>>> tuned) using some pretty rigid RG58U, and will try it along with a 6"
>>> diameter tuned loop (adjustable between 20 and 30 MHz). I have
>>> basically tracked the RFI down to a room, but the room is packed
>>> full of motor controls (numerous VFDs, etc.). The 3" diameter loop
>>> appears to be working well with my SDR receiver based on some simple bench
>>> top testing I just did.
>>>
>>> Thanks,
>>> Don (wd8dsb)
>>>
>>> On Fri, Feb 2, 2018 at 4:00 PM, Cortland Richmond
>>> <ka5s@earthlink.net<mailto:ka5s@earthlink.net>>
>>> wrote:
>>>
>>> Hi, gents. Cortland here, KA5S.
>>>> I had about a 30 year career in EMC engineering, and often had
>>>> to locate specific sources of EMI.
>>>>
>>>> A quite small loop will do very well if one is in close proximity
>>>> to the magnetic field of an emitter. That is, there is a good deal
>>>> of utility in entering the near field very closely.
>>>>
>>>> You may remember the famous 3520 kHz television modems of some years ago.
>>>> For those I tried using three antennas; a surplus EMC loop antenna
>>>> about
>>>> 1
>>>> m in diameter, ad un-tuned whip antenna, and about a 3 inch loop
>>>> antenna made by bending a piece of semi-rigid cable back on itself
>>>> and soldering the exposed center conductor at the
>>>> non-connectorized end to the outside of the shield near the connector.
>>>>
>>>> This last was unbalanced, but its small wavelength aperture made it
>>>> good almost through VHF.
>>>>
>>>> At 80M, on a handheld receiver, it could accurately lead me to the
>>>> exact room one of those modems was radiating from.
>>>>
>>>> Much smaller loops can be constructed on the open end of a single
>>>> piece of coax, and can follow individual traces on a PWB – but that
>>>> is beyond the scope of this discussion.
>>>>
>>>> Good luck!
>>>> Cortland
>>>> ka5s
>>>>
>>>>
>>>> On 2/2/18 2:32 PM, Don Kirk wrote:
>>>>
>>>> Hi Dave and gang,
>>>>> I totally agree on the smaller loop, but I believe what is also
>>>>> important is to factor in the implications of being in the near
>>>>> field. That's why I think going to a much higher frequency would
>>>>> be very beneficial (get out of the near field as much as possible,
>>>>> but we will see).
>>>>>
>>>>> Stay tuned (no pun intended).
>>>>>
>>>>> Don (wd8dsb)
>>>>>
>>>>> On Fri, Feb 2, 2018 at 1:51 PM, Dave Cole (NK7Z)
>>>>> <dave@nk7z.net<mailto:dave@nk7z.net>> wrote:
>>>>>
>>>>> I would try a a much smaller mag loop, like a foot in diameter. I
>>>>> have
>>>>>
>>>>>> used a 6 inch loop in some cases, they are still sort of directional.
>>>>>> Add a
>>>>>> ferrite on the coax at the feed point. I have one loop that is
>>>>>> about an inch in diameter, I use it seldom, but it is handy when
>>>>>> needed.
>>>>>>
>>>>>> I also have a small probe I built out of a piece of coax, I just
>>>>>> cut the shield back 3 inches, used dollop of liquid electrical
>>>>>> tape on the end of the center conductor for insulation, and then
>>>>>> I probe around...
>>>>>>
>>>>>> 73s and thanks,
>>>>>> Dave
>>>>>> NK7Z
>>>>>> http://www.nk7z.net
>>>>>>
>>>>>> On 02/02/2018 10:20 AM, Don Kirk wrote:
>>>>>>
>>>>>> Quick follow up on my locating the source of the repeating
>>>>>> 15 KHz
>>>>>>
>>>>>>> signal
>>>>>>> (actually 15.6 KHz).
>>>>>>>
>>>>>>> Today I met with the suspect facilities machine controls
>>>>>>> engineer that just happens to be an inactive but still licensed
>>>>>>> ham (turns out we also have mutual friends in the machine controls
>>>>>>> world).
>>>>>>>
>>>>>>> I first walked around the entire perimeter of the building
>>>>>>> (outside in very cold temperatures) using my portable SDR
>>>>>>> system, and was able to determine that the source of the
>>>>>>> interference is located near the west central part of the
>>>>>>> building where there are several water cooling towers as well as
>>>>>>> material storage silos. The signal is indeed cyclic but still
>>>>>>> need to see how repeatable the cycle is (typically on for about
>>>>>>> 20 minutes and then off for about 20 minutes). Inside the west
>>>>>>> wall there are a bunch of facilities related equipment (pumps,
>>>>>>> variable speed drives, etc.).
>>>>>>> Unfortunately my 160 meter tuned loop is useless when in so
>>>>>>> close to the source, and we were not able to determine the
>>>>>>> actual source in the allotted time we had today. With the SDR
>>>>>>> receiver gain set at 0, the signal was still near full scale
>>>>>>> when in close to the source (it appears we have the source
>>>>>>> nailed down to about a 50 foot by 25 foot area, but there is a
>>>>>>> ton of motor controls equipment in this small area as well as
>>>>>>> metal building structure that likely is confounding our DFing).
>>>>>>>
>>>>>>> We are now going provide my vehicle description, name, etc. to
>>>>>>> the security department that patrols the grounds of this
>>>>>>> facility so they know I have permission to be on the property 24
>>>>>>> hours a day 7 days a week. I'm going to obtain more data on the
>>>>>>> cyclic nature of the interference (to see if it provides any
>>>>>>> clues), and also evaluate capturing the signal at much higher
>>>>>>> frequencies (determine what the highest frequency is that I can
>>>>>>> still capture the signal), and then build a DF antenna for the
>>>>>>> higher frequency to help pinpoint the source when in close.
>>>>>>> After I obtain more data from outside the building and develop a
>>>>>>> better antenna for in close DFing, I will then go back into the
>>>>>>> building to continue our in close DFing (as time permits).
>>>>>>>
>>>>>>> My portable SDR system consists of a Dell laptop, NooElec SDR
>>>>>>> dongle, and ham it up converter (stuck to the back of the laptop
>>>>>>> screen using double stick tape). The SDR dongle and ham it up
>>>>>>> converter are powered via the laptop USB ports which makes it
>>>>>>> very convenient. I just plug my DF antenna into the ham it up
>>>>>>> converter and adjust the SDR dongle gain as needed (via the
>>>>>>> SDRSharp software I'm using).
>>>>>>>
>>>>>>> Just FYI,
>>>>>>> Don (wd8dsb)
>>>>>>>
>>>>>>> On Mon, Jan 22, 2018 at 9:15 AM, Don Kirk
>>>>>>> <wd8dsb@gmail.com<mailto:wd8dsb@gmail.com>> wrote:
>>>>>>>
>>>>>>> Yesterday I tracked down RFI that has been bothering me on 160
>>>>>>> meters for
>>>>>>>
>>>>>>> the past year. The source was a little hard to find because
>>>>>>> it's not
>>>>>>>> always on. I finally had to use my SDR dongle with Ham it up
>>>>>>>> converter in the car with my small tuned loop to track down the
>>>>>>>> source of the interference (in order to make sure what I was
>>>>>>>> seeing at home was what I was actually tracking). The suspect
>>>>>>>> source is 0.75 miles from my house.
>>>>>>>> Here is a link to a video showing my efforts to date.
>>>>>>>>
>>>>>>>> http://www.youtube.com/watch?v=LKf1EWTV8xs
>>>>>>>>
>>>>>>>> Today I will contact the manufacturing facility that I tracked
>>>>>>>> the RFI down to in order to take the next step with them.
>>>>>>>>
>>>>>>>> I will report the actual source of the RFI as soon as it's
>>>>>>>> determined which might take some time (usually takes time to
>>>>>>>> establish a good working relationship with the suspect property
>>>>>>>> owner). Based on past experience it sure looks like a variable
>>>>>>>> speed drive, but in order to keep an open mind I try not to
>>>>>>>> guess ahead of time.
>>>>>>>>
>>>>>>>> Just FYI,
>>>>>>>> Don (wd8dsb)
>>>>>>>>
>>>>>>>> _______________________________________________
>>>>>>>>
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Dave - WØLEV
Just Let Darwin Work
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