You could build yourself a 1/2-wavelength dipole decoupled with clamp-on
ferrite to form a standard antenna. The antenna factor of a dipole is well
known. You could make real measurements, especially if you use the older
substitution method using the dipole and a sig gen. That can be made quite
rigorously.
Addressing the local installer, I'd recommend running through the basics of
your measurements before you turn anything on. They might understand the
time domain - o'scopes - but have no clue of the frequency domain
measurements. I usually use the FM or AM BC bands on the spectrum analyzer
for such purposes.
Just trying to help your cause (and all of us)!
Dave - WØLEV
On Tue, Sep 8, 2020 at 11:57 PM Karin Johnson <karinann@tampabay.rr.com>
wrote:
> David:
> The zero span pictures are exactly what exists as RF signals from the
> switcher at a center frequency of 6.4 MHz. That is where the spectrum
> analyzer is tuned. The timing between each pulse is a little less than 60
> microseconds. Since the drive to the compressor motor is 3 phase, I am
> assuming there are three pwm pulses sent to the motor during a cycle. If
> you multiply the period between Pwm pulse approximately 60 usec by 3,
> ie: 180 usec, then the period of the 3 phase cycle is about 5555 Hz. This
> corresponds with the brief documentation I have found indicating about 6500
> Hz for the motor drive. I don’t have and haven’t found the detailed
> instruction manual for the Emerson EV2 inverter drive.
> I spoke with Rheem today and they encouraged me to work with their local
> Distributor Service Coordinator. I have to work thru the installer first.
> A tech is coming out tomorrow. Don’t know how much help he will provide
> But at least it is a start. I have as much information as is available
> with
>
> Internet searching so far. As indicated there are a couple of documents
> Missing yet. Also I am very curious what the Low Pass cutoff frequency is
> For the Inverter Drive input filter. I have the equipment to measure it
> if
> The tech is willing to remove it for me for an hour or so.
> The purchase price is about $230 USD, and it is available at the local
> Rheem parts distributor.
> Since the spectrum plots were taken from a bandwidth limited antenna and
> the
> Internal wiring plus the house wiring also contribute to the spectrum
> shape,
> It is difficult to determine what the actual real levels are.
> In the past when I have worked with EMC/RF test ranges the antennas were
> Calibrated and wideband data was available to compute the "Antenna Factor"
> During the EMC testing. This is not the case here.
>
> Karin Anne Johnson P.E. K3UU
> Palm Harbor, FL
>
> ________________________________________
> From: David Eckhardt [mailto:davearea51a@gmail.com]
> Sent: Tuesday, September 08, 2020 7:25 PM
> To: Karin Johnson
> Cc: Rfi List
> Subject: Re: [RFI] Rheem HVAC RFI Link to document
>
> Excellent documentation! I have found that 'fuzzy' traces don't always
> communicate what you are attempting. I use the max hold function to better
> display the magnitude of the interference between powered but off and
> everything on.
>
> Also, with your zero-span captures. What do the tynes represent? Possibly
> run a relatively narrow span like 1 MHz or 0.5 MHz and a narrow RBW to
> bring
> out the 6 kHz tyne spacing from the switcher. To the supplier, that would
> nail the switcher as the problem.
>
> Dave - WØLEV
>
> On Tue, Sep 8, 2020 at 5:49 PM Karin Johnson <karinann@tampabay.rr.com>
> wrote:
> Hello again group:
>
> I created a power point document outlining some of the measurements
>
> I've taken with regard to the RFI source from the new Rheem HVAC heat
>
> pump system recently installed.
>
> I've been accumulating as much documentation as I can via internet sites.
>
> Some of the user manuals are available, but the important ones regarding
>
> the Power inverter drive user manual and the communication baud rate from
>
> the ECONET thermostat are not available. I will continue to look.
>
> I am doing this work now with regard to information gathering so that I can
>
> address this issue with the installer to help me look at solutions without
>
> voiding any warranty should I take off mechanical coverings on the unit
> without their help.
>
>
>
> Here is a link to the document at Google Drive.
>
>
>
>
> https://drive.google.com/file/d/1FYIZseDnlsM8UMfnAGhPUjJ7aPMJ2xCT/view?usp=s
> haring
>
>
>
> I've allowed anyone to view this. It should work. If it doesn't let me
>
> Know via this forum and I will see if I set the permissions incorrectly.
>
>
>
> Karin Anne Johnson P.E. K3UU
>
> Palm Harbor, FL
>
> _______________________________________________
> RFI mailing list
> RFI@contesting.com
> http://lists.contesting.com/mailman/listinfo/rfi
>
>
> --
> Dave - WØLEV
> Just Let Darwin Work
>
>
>
--
*Dave - WØLEV*
*Just Let Darwin Work*
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