[Lowfer] New smaller ferrite cores

[Bill Ashlock]

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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