[Boatanchors] Filament Choke

[Jim Bromley, K7JEB]

On 9/2/2018 3:15 PM, Jim Bromley, K7JEB wrote:

> http://coil32.net/online-calculators/ferrite-rod-calculator.html
>
> 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 ;-)

k7jeb