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I have been winding some transformers recently
and have been getting some odd results.
All cores have a prim of 9 turns and 27 turns
sec.
1. 3C85 58 mm diam Prim inductance 167uh Sec 744
uh
2. Same material abt same size but E core Prim
292 uh Sec 2810 uh no gap.
3. Material unknown out of a smps similar
size Prim 21 uh Sec 178 uh no gap
4. TV lopt core again abt same size Prim 79 uh Sec
865 uh no gap
The Prim wire is litz 2mm and sec 1mm copper enam
wire in all cases.
1 and 2 seem to have a big difference considering
the same material, 3 must have a low u.
Has anyone else tried comparisons of
cores.
If cores are selected at random and not checked
there would be a big variation in results even using the same turns
ratio.
The above are intended as output matching
transformers in the FET amps like the YXM and MRF class D/E design.
I normally use 1 in my amps but have tried 3 and in
spite of the big difference in values it does seem to work and I have not
noticed any difference in RF output, which seems strange.
73 de Mal/G3KEV
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