[Boatanchors] Filament Choke
Jim Bromley, K7JEB
k7jeb at cox.net
Sun Sep 2 19:56:19 EDT 2018
On 9/2/2018 3:15 PM, Jim Bromley, K7JEB wrote:
> I used #8 wire as an approximation to 2 - #10's and
> came up with 174 uH.
And that's way too high. Using #4 wire as an
approximation to 2 - #10's and walking the
calculation up to a 6.5" coil on the 7.5" core
gives me N = 32 turns and L = 82 uH.
BTW, that Al = 49 is in millihenries/1000 turns
because it's a ferrite, so the desired inductance
has to be specified in millihenries.
For L = 0.082 mH, the number of turns N is:
N = 1000 x SQRT( L / Al )
= 1000 x SQRT( 0.082 / 49 )
= 41 turns
which is almost in the ballpark. 82uH = 927 ohms
at 1.8 MHz.
Just cram as many windings on the rod as you can
get and be done with it ;-)
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