Tehrasha Darkon wrote in news:f100t5$rsc$1
@news.netins.net:

....
It is very good information, provided you are dealing with cores of a
known type. (#31 or #43) It would be nice if I had such material, and
in the end I may have to resort to purchasing some. *SHOCK*

But as it is, I am looking at some cores that appear to be #35
material,
and I cannot find any information as to how they react at freq. They

Keep in mind that cores for chokes for suppression purposes need not and
are usually not of low loss material. Often the materials used for
suppression up to 500MHz might be quite lossy above 1MHz. Not only does
that loss not prevent them being effective, it is the main mechanisme
operating above typically 10 to 50 MHz. #43 is such a material.

I can't help you with characteristics of #35 material.

You might have to try to characterise it yourself, it isn't hard if you
have access to an MFJ259B or the like (or better). It is easy enough,
here is one I did for a part readily available in Australia:
http://www.vk1od.net/balun/index.htm . BTW, these cores cost about A
$35/metre whereas #43 cores of similar OD & ID cost about A$586/m (a
1600% price increas), or translated to a 300mm length for a balun, the
Jaycar LF1258 costs A$10.50 vs T-37-43 for A$175. (I know that the #43
cores are much cheaper in the US.)

Owen