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


KI7MWA
 

Been assembling an 80 meter band pass filter, and have consistently had to remove 6 turns during the tuning phase (using a nanovna).  This most recent attempt, I used my Peak LCR45 to measure the initial inductance, before installing the toroid.  With the recommended 34 turns (4 more than the design "design" number, 30), I get 5+ uH.  Pulling the extra 4 turns gives me 4.3 uH.  The design value is 3.8 uH.

Anyone with similar experience?  Or am I doing something wrong here?

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