[RFI] Eliminating TVI

[Pete Smith]

At 12:21 PM 12/27/03 -0500, Tom Rauch wrote:
>I generally build my own because the commercial filters I find either have
>output and input bypass capacitors to common grounds [A] making them poor or
>useless for common mode rejection or they have bifilar windings with poor or
>NO shunt caps between the lines [B] making them poor at differential mode
>rejection.


I would infer from this that if you knew what was inside the boxes, it 
might be possible to build a fairly decent filter by putting one of type A 
and one of type B in series.  Is that correct?

Alternatively, I see on page 1077 of the current Mouser catalogue that 
Schurter appears to make some 1 and 2 stage filters that do this all in one 
package.  Do any of those meet your specs for HF  rejection?  There are a 
number of others on the facing page by Schaffner that make claims to high 
differential and common mode rejection, but no circuit diagrams are 
included.  Looking at the data online, they appear to be similar to the 
Schurter units, and claim quite high rejection for both common and 
differential modes in the HF range (assuming I am reading the curves 
correctly, which is not at all certain).

See 
http://www3.schaffner.com/components/emc_filters/_pdf/single-phase/ds_FN_332.pdf.


73, Pete N4ZR
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