[Amps] Help constructing filament choke for pair of

[Paul Baldock]

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