[Lowfer] LRC Meter

[Bill Ashlock]

>Further, Bill raises the practically of a LRC being handheld and
>portable. Yes, I too have asked many a hamfest vendor "what material are
>these," about cores, and hearing an I don't know.
>So, Bill, what do you do in such a case? Stick a few turns around a
>core and plug it in having a known good one at hand?

It's fairly easy to recognize the popular ferrites (43, 61 and J) by the 
inductance if one turn (sometimes 2) but I take along a spec sheet from 
Amidon (or equi) that has the full product line, occasionally, to help out. 
The ferrites are usually not color-coded and have a distintive non-painted 
dull dark gray appearance. The J type are not as dull. Comparing 1" OD by 
1/2" height cores, the very common #43 will have about .7uh and the J type 
about 4uh. The #61s have a reading of about .1uh, my lowest count, so I use 
2 turns and look for .4 uh. (since the inductance runs to the square of the 
turn count)

The powdered iron cores require a different approach. The inductance per 
turn is much lower and this requires more turns. Most are color-coded but 
I've seen different coding schemes between manufactures, so data sheets are 
useful. Powered iron cores are much more critical to frequency compared to 
ferrite, so knowing where to find data on a particular color is important 
and knowing the inductance for one turn goes a long way to help the ID 
process.

Bill A

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