Inductors of LPF wound onto the same toroid

[neazoi]

Hi, I would like to design a LPF for HF
**broken link removed**
the series configuration (two coils).
I was wondering if I could wind both coils onto the same toroid (same or opposite phase?), or if it should not be done that way at all?

 

[volker@muehlhaus]

No, you can't do that because it would create magentic coupling between the inductors. For the low pass function, it is important that both inductors are NOT coupled.

 

[neazoi]

No, you can't do that because it would create magentic coupling between the inductors. For the low pass function, it is important that both inductors are NOT coupled.

Thank you.
Even if winding the coils in different phase or some other weird way?

 

[chuckey]

Because as the signal travels down the sections of the LPF, its voltage/current phase changes at each section, there is not anywhere where they can be cancelled out.
Frank

 

[neazoi]

Because as the signal travels down the sections of the LPF, its voltage/current phase changes at each section, there is not anywhere where they can be cancelled out.
Frank

Thanks, so I guess I should better use an L-type LPF if a single core is to be used.

 

[biff44]

if you are really good on filter design, you can use the coil coupling as elliptical poles to your advantage. but you do not sound like a filter expert, so don't even try.