[Lowfer] Ferrite Toroid vs. Binocular Ferrite

[Chris Trask]

>
>Hello The Net:
>
>For the same ferrite material, what is the difference in the performance 
>between a binocular and a toroid form factor ?
>
>My preliminary thinking is that the same pri and sec turns will yield
>the same bandwidth and performance  on either.
>
>What is the wisdom and experience ?
>

     First of all, toroids are far better suited for power applications, from both a construction (working with heavier wire) and performance (coupling coefficient) perspective.  Binocular cores are best suited for small signal applications, especially when you can twist the wires in bifilar and trifilar groups.  One notable exception is with regard to low impedance transformers, such as would be encountered with loop antennas.  The powdered iron materials needed to reduce the losses are only available in toroid form.

     Secondly, when working with transformers whose ratios preclude the use of twisted wires, toroids give much better performance, especially if you can place the windings in such a way that they end up as a single interlaced layer.  The better coupling that results will yield better bandwidth performance, though twisted wires will yield the best bandwidth performance for either toroids or binocular cores.



Chris Trask
N7ZWY / WDX3HLB
Senior Member IEEE
http://www.home.earthlink.net/~christrask/