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eHam Forums => RFI / EMI => Topic started by: WB4BYQ on November 12, 2012, 08:13:05 AM



Title: Look at these AC EMI/RFI Filters
Post by: WB4BYQ on November 12, 2012, 08:13:05 AM
Study this company with their filters.  Even filters with power cords and plugs.

http://www.filterconcepts.com/

WB4BYQ


Title: RE: Look at these AC EMI/RFI Filters
Post by: WB4BYQ on November 16, 2012, 03:41:17 PM

RE: PowerLine RFI Filter for Samsung Plasma TV


Look like you folks could build a RFI filter for the Samsung Plasma TV.  Lots of RFI into the power lines
In the home then into the triplex to the power grid.  RFI flows on the ground wires as well.  As a
Amateur Radio operator for 40 years I have seen this first hand.  See what your filters will do.

Richard,
 
The filter that we would recommend is our CF151 (attached).  The unit cost for quantity 1-9 is $ 226.00 FOB our dock.  Delivery is stock to two weeks ARO. We accept American Express, MasterCard, and VISA credit cards.  This quotation is valid for 45 days from today.
 
Regards,
 
 
John Erwin
Sales
(714)545-7003


this may help someone.    http://www.filterconcepts.com/


Title: RE: Look at these AC EMI/RFI Filters
Post by: KH6AQ on November 17, 2012, 10:24:15 AM
The mechanism by which plasma TV screens couple RF noise current is displacement current to the room then back through the AC power cord GND. The common-mode impedance of this path is roughly 1-2 k ohms at 3.5 MHz.

To attenuate this noise by 20 dB (3 S-units) requires a filter having a CM (Common-Mode) impedance of 10 to 20 k ohms. It must include the GND, Line, and Neutral. Very few EMI filters include CM filtering on the GND wire and 10 to 20 k ohms CM impedance is not to be found in any EMI filters I am aware of.

The way to get this high CM impedance, and include all three AC wires, is to wind the TV power cord through #31 or #43 ferrite cores. Several separate CM chokes need to be cascaded as core loss limits the maximum CM impedance of each choke to perhaps 3-5 k ohms.



Title: RE: Look at these AC EMI/RFI Filters
Post by: K0IZ on November 18, 2012, 06:35:42 AM
I have had excellent results with Corcom EMI filters.  Always a bunch for sale on eBay, usually in the range of $10 to $15.
Different amp ratings, mine are 20amp.

Here is the specific model that I use:

http://www.ebay.com/itm/NEW-CORCOM-EMI-FILTER-20VW1-20-AMP-120-250-VOLTS-50-60-HZ-/380470679653?pt=LH_DefaultDomain_0&hash=item5895d1d865


Title: RE: Look at these AC EMI/RFI Filters
Post by: WB4BYQ on November 18, 2012, 03:16:34 PM
I have the pdf file for the filter that was suggested.  the filter is inside a metal box, with power cord to the wall, and nema plug on the other side.  according to the schematic from the pdf
the filter is brute force and the ground has been wound with an inductor.  i have the AC power
interference handbook by marv loftness.  his book on page 14-15 printed is a schematic of a
brute force common-mode / differential mode choke with common mode choke in safety ground wire.  these filters are sold at different locations.  have not been able to insert the pdf into the message to show the unit that is for sale.  i am suggesting a product that will look professional and be consider safe to place into someone's home to filter rfi.  i suggest that if anyone looks at
this website look at the home automation section for filter ideas and request the pdf for the CF151 to look at.

richard