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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