At 04:33 AM 7/8/2013, Jim Thomson wrote:
#### why does half the turns result in one qtr the uh ? I can see maybe
slightly less than half the original uh..but not a qtr.
Inductance is proportional to aprox no of turns squared with a
ferrite core. 1/2 squared is 1/4. If you were to keep the length the
same (ie double the wire size) then the N squared factor would be
close to perfect.
Did you shift the remaining turns to the center of the rod.....or
just leave them
down at one end ?
Usually just down one end. On a recent SB200 mod I actually did not
remove any turns for 6M. The coil was already looked rather small and
I suspect marginal at 80M although I did not bother to measure the
inductance as it worked fine at 6M.
- Paul
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