[RFI] ebay line filters

[Doug Powell]

One thing you should realize about line filters is they are optimized for conducted line emissions coming from the product where they are built in. This means the line / load labeling  ‎will determine your best orientation for connection. If you are attempting to protect your own gear, you can reverse a filter if you wish and there will be no harm to the filter itself. Also, the case of the filter needs to be well bonded to the chassis of your equipment. 

As for the effectiveness of a line filter, much of a filter's design is not just the components but the internal layout of the components and the internal wire routing. I have worked professionally with line filters for many years and if there's anything I have learned it is that manufacturer's data sheets have little to do with your specific application. For one thing, all the measurements they report use 50 Ohm matched signal generators and analyzers. The real world of power lines are a far cry different than 50 Ohms.

Possibly, the best thing you can do is to perform your own sweep using a LISN or a Tastkoph probe which will protect the analyzer from the line voltage.  Identify what is the RF noise profile you currently have, then locate a filter that has good attenuation numbers at the points of concern. Most of the time line filters are effective in the 100 kHz to 100 MHz range.  

All the best, Doug


Douglas E Powell‎
dougp01 at gmail.com ‎
‎https://www.linkedin.com/in/dougp01

 
‎
 
  Original Message  
From: Dave Cole
Sent: Monday, August 15, 2016 5:41 AM
To: rfi at contesting.com
Reply To: dave at nk7z.net
Subject: Re: [RFI] ebay line filters

On Mon, 2016-08-15 at 10:02 +0100, PY1NB - Felipe Ceglia wrote:
> Hello,
> 
> I need to buy some EMI line filters in te range of 3 to 10 amps. I
> found a plethora of them at Ebay, but none of those I found had tables
> or curves for how much they attenuate on the spectrum.

How odd it is that you ask that, just yesterday I was looking at eBay
for a line filter, and decided I needed more information.  I located
this:

http://www.te.com/usa-en/products/emi-filters/power-line-filters/interse
ction/high-performance-power-line-filters.html

Which will give you a secret decoder chart for the Corcom filters...

-- 
73's, and thanks,
Dave (NK7Z)
For software/hardware reviews see:
http://www.nk7z.net

_______________________________________________
RFI mailing list
RFI at contesting.com
http://lists.contesting.com/mailman/listinfo/rfi