[HomeBrew] winding toroids

[Jim Kearman]

> I am wondering where I can read up on winding trifilar toroids for double 
> balanced mixers.

As I recall, with broadband transformers, you want an impedance _ratio_, but you are not looking to make the impedance of the windings _match_ the impedance of a source or load. I believe Demaw mentioned somewhere making the winding Z about 10 times the source or load at the operating frequency. That's been my rule of thumb. I calculate (or look up) the impedances looking into or out of the windings, then make the number of turns equal about 10 times that impedance, although I have fudged lower a few times so I could use a smaller core. 

73,

Jim, KR1S
http://kr1s.kearman.com/