Re: 80 meter bpf toroid winding 30 turns givel 4.3 micro Henrys, not 3.8


KI7MWA
 

So, I wound it again and got the design value (3.83 uH).  The problem, really, is that, tuning with the nanovna, I have to reduce the turns to 28 (I've done this 3 times now), and when I trim the extra wire and check it again, I've passed the tuning point (trimmer cap is no longer about half way open).  I am aiming for a center frequency of 3.75 MHz (too high?).  Best insertion loss I've achieved is around -3.5 dB.

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