[RFI] Rheem HVAC RFI Link to document

[Karin Johnson]

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 at 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 at 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

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-- 
Dave - WØLEV
Just Let Darwin Work