Re: Many uBitx's have reduced power on 40m CW

Jerry Gaffke

The AL of a T30-6 core can vary +/-5% of the nominal value, and inductance is proportional to AL.
Yet another handy factor to blame bad results on.

Inductance is proportional to the square of the turns count.
Having 8 turns instead of 9 is a 100*(9*9-8*8)/(9*9) = 21% reduction in inductance.

Different spacing around the core and loose vs tight windings can make a sgnificant difference.
As you have noticed.

Jerry, KE7ER

On Wed, Apr 7, 2021 at 04:27 PM, Evan Hand wrote:
The most recent observation is that there is a HUGE variation in the inductance of the toroids depending on the turns AND the spacing. 

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