[TowerTalk] CM choke using Fair-Rite 52 mix

[Jim Brown]

On 5/3/2012 2:17 AM, Steve Hunt wrote:
> I just started making measurements on some CM chokes using Fair-Rite's
> #52 mix - it looks quite useful for the upper half of the HF spectrum.
> Here is a typical result:
> http://www.karinya.net/g3txq/temp/52_mix.png

Thanks for the "heads up."  I concur with your assessment that this 
material could be quite useful in the higher HF bands. Note that 
Fair-Rite has not yet established specs for parts made with this 
material for suppression -- they are currently listed only as inductive 
components (primarily for use below about 5 MHz), and carry 59-series 
part numbers.

For inductive components, the primary specs are for permeability at the 
lower frequencies where the material has relatively low loss, and there 
are no plots of impedance vs frequency. For suppression components, the 
primary specifications are for impedance as a function of frequency in 
the spectrum where the material is lossy, and thus useful as a common 
mode choke. Data sheets for suppression components DO include graphs of 
impedance vs frequency, and often for 1-3 turns. When they get around to 
specifying suppression performance they will assign 26-series part 
numbers to toroids and other solid cores and 04-series numbers for 
clamp-ons.

It should be noted that the difference between parts with inductive part 
numbers and suppression part numbers is how they are controlled in 
manufacturing and how they are tested for compliance with the 
performance specs.  That is, an inductive part number is tested for its 
mu and loss tangent at the low frequencies where it would be used as an 
inductor, and a suppression part number is tested at the higher 
frequencies where it is used for suppression.

73, Jim K9YC