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[RFI] Power Over Ethernet from Switch Mode Power supplies

To: rfi@contesting.com
Subject: [RFI] Power Over Ethernet from Switch Mode Power supplies
From: Chuck Gooden <Chuck.Gooden@comcast.net>
Date: Sun, 7 Jul 2019 18:26:14 -0500
List-post: <mailto:rfi@contesting.com>

I am currently experiencing RFI issues on 40 meters and below. Some, but not all, of these issues are due to the Power over ethernet (POE) switches that I am using.  I have two POE switches and 2 Wirelass Access Points (WAP).  The switches are powered by a 48 volt 1.3 amp switching power supply and can supply power to 4 of the 8 ports.  I currently only use the POW on the switch to power a network cloud key controller.  The WAP's also have a 48 V switching power supply connected to an ethernet power inserted. So in this configuration I am using 3 of the switching power supplys.

I am considering redoing my network wiring so I connect the two WAP's to one of the switches (#1) and power my second switch from one of the POE ports also on the switch.  This will involve running more ethernet CAT5 cable but will get rid of 3 SMP power supplies.

I would like to replace the switching supply with a linear power supply with a 48 vdc 3 amp supply but the lowest cost one I see runs about $150.  I have found a cheaper switching supply for $16.40  see

https://www.digikey.com/product-detail/en/mean-well-usa-inc/RPS-60-48/1866-4074-ND/7706100&?gclid=CjwKCAjwsIbpBRBNEiwAZF8-z7KemHIR0-Y6iHlnUyYMFaKFOUEIM5mTTqovlNSTq89bJMvSkC7jfRoCRcAQAvD_BwE

If you follow the link to the datasheet you will see the conductive and radiated emissions meets EN55011 class B, but that does not seem very acceptable from what I found on the ethernet as to the levels for a class B device.

Is there any steps that I can take with this power supply to reduce the radiated and conductive emissions if any?  Like mounting it in a metal EMI case, Torrids on both the input and output leads, more capacitance on the output, etc.

Chuck K9LC


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