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To: [email protected]
Subject: LF: CORES
From: "hamilton mal" <[email protected]>
Date: Tue, 17 May 2005 00:24:59 +0100
Delivery-date: Tue, 17 May 2005 15:13:21 +0100
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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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