[TVI-RFI-EMI] Characterize ferrite material of NOS toroids from VNA tests at RF frequencies?

[Ray LaRue]

I have a number of supposed type 43 and type 31 large ferrite toroids. I 
also have a number of clamp-on cores of unknown materials. I have 
fabricated a simple low capacity jig and I have a couple small VNA's.  
My intent is to use the toroids as RF chokes on coax and other cables.

I have tested several of these cores with one and multi-turn loops thru 
the cores, reading the resulting impedances at several HF ham bands. 
This gives a pretty good idea of the choking impedances for a given 
number of turns.

However, I have not been able to translate this information into 
characterizing what materials each core is made of.

My query is: how do others determine the type of ferrite material of a 
given core? I would be interested if you have a different approach to my 
concern, or can add some insight to my tests.

Your attention is appreciated.
Ray, W4BYG


-- 
"If you want to build a strong house, I'll give you my engineer's number.
  If you want to build a strong life, I'll introduce you to my carpenter."
   Lebron and Heather Lackey



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