[Lowfer] New smaller ferrite cores

[Jay Rusgrove]

Bill

I'm surprised. Did the .375 run with elevated temperature?

Jay

Bill Ashlock wrote:

> Jay and other TX Loop Enthusiasts,
>
> Today I received the 3/8" and 1/4" OD #77 ferrite cores Jay sent to try out
> for the stepdown transformer of my breadbord final. I just tested the 3/8"
> core - which looks so strange with a #14 AWG insulated wire running through
> the center (just enough room for 12 turns of #30 on the primary). Low and
> behold, as far as I can determine, the efficiency of the final is still 95%
> at 1W! This is in spite of the reduced primary inductance of only 160uh.
> Think the size of the complete final is, now, down to the size of a SMALL
> postage stamp. I'll have to see if the math works out for saturation
> characteristics for a core this small. Probably the fact that I'm driving it
> with a square wave has a lot to do with these unexpected results.
>
> Jay, I'll test the 1/4 inch core later but the primary inductance will be
> about half of the above so I'll have to double the turns on both primary and
> secondary.
>
> Bill
>
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