[RFI] Solar Panel RFI in Kings Park - Update October 4th 2018

[Dave Cole (NK7Z)]

Also, at some point, take a site survey, or two, as outlined here:

https://www.nk7z.net/sdr-rfi-survey-p1/

of your RFI.  Then as they make changes you can show then, and document 
the changes, across a wide swath of spectrum.  If you can use a non 
resonant antenna it helps in getting everything as flat in response as 
possible.  It is all relative anyway, but the effort to make flat is 
always good.

I use a BWD-90, which supposedly is close to flat across 3-30 MHz as the 
SDR antenna.  I can now test just how flat it is, as I have a noise 
generator that tests flat from 1 to 500 MHz., on my Spectrum Analyzer.

I'll set up the noise generator on a very short antenna, (as non 
resonant as I can make it), antenna a block away, and see just how flat 
the BWD-90 is...  Then I can add correction factors to the spectrum from 
the SDR tests, and get an actual set of meaningful numbers.


73s and thanks,
Dave (NK7Z/NNR0DC)
https://www.nk7z.net
ARRL Technical Specialist
ARRL Volunteer Examiner
ARRL OOC for Oregon

On 10/7/18 9:50 AM, Gary Smith wrote:
> 
> They fill the optimizer with foam, the noise goes away and so do the 
> techs from the solar panel company.
> 
> Meanwhile, time comes and goes and the foam looses its tenacity and the 
> noise comes back.
> 
> Torroids are your friend not Chinese (betcha it is made there) synthetic 
> foam rubber.
> 
> Gary...wa6fgi
> 
> 
> On 10/6/2018 1:38 PM, Tony Brock-Fisher via RFI wrote:
>> /'They determined the noise to be one and the same'. /
>>
>> This is a HUGE win. Now you have them concentrated on fixing the 
>> offending location, instead of spending their time spinning their 
>> wheels, looking for other causes!
>>
>> I agree, the idea of 'RF absorbing foam' sounds like snake oil. But if 
>> you got them to put large solid chokes on, then let them go on 
>> thinking the RF foam fixed it...
>>
>> Also, improving the ground system  may not help and may actually hurt, 
>> if they increase the coupling of noise into the ground. It is 
>> important that the ground rails do not provide a 'sneak path' around 
>> any ferrites installed on cables with ground, such as at the 
>> connection from the roof to the home run. Specifically, in figure 3 of 
>> my article, you must make sure that the bare ground conductor passing 
>> thru the chokes does not make accidental contact to the rails before 
>> it has exited the last choke in the string (the left hand one in 
>> figure 3).
>>
>> -Tony, K1KP
>>
>>
>> On 10/6/2018 4:04 PM, Tom Thompson wrote:
>>> It won't.  If you put a transmitter inside a screen room with an 
>>> external antenna, it will radiate.
>>>
>>> Tom   W0IVJ
>>>
>>> On 10/6/2018 1:59 PM, Tony wrote:
>>>> All:
>>>>
>>>> The RF Engineers from Solar Edger came out to my home this week to 
>>>> assess the noise emanating from my neighbors solar panel system.
>>>>
>>>> They plugged into my antennas to view the spectral noise on my 
>>>> receiver which they then compared to the spectral noise that 
>>>> appeared on their portable setup near the solar panels. They 
>>>> determined the noise to be one and the same.
>>>>
>>>> The next course of action is to improve the ground system and 
>>>> install RF absorbing foam to each optimizer. I also convinced them 
>>>> to replace the snap-on ferrites located at each optimizer, with 
>>>> larger ones so they can loop several turns of cable around each core.
>>>>
>>>> They originally said they would just go with the RF foam which is 
>>>> puzzling: I don't understand how encasing a noisy device with this 
>>>> stuff could suppress RFI when the device is attached to long runs of 
>>>> cable that act like antennas. Can anyone explain how that would work?
>>>>
>>>> Tony -K2MO
>>>>
>>>>
>>>>
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>>>>
>>>
>>
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