[Lowfer] I need the formula to calculate needed turns on a coil

[Warren Ziegler]

Andy,

       The formula for the inductance of an air-wound coil is
L = a^2*n^2/(9a + 10b)
Where L - inductance in microhenries
           a - radius of coil (inches, be careful its radius not diameter)
           n - number of turns
           b - length of winding (inches)

A useful calculator is DL5SWB's mini-ring core calculator which does
air wound coils as well as toroids:
http://www.dl5swb.de/html/mini_ring_core_calculator.htm
its great freeware!
-- 
73 Warren K2ORS
                WD2XGJ
                WD2XSH/23
                WE2XEB/2
                WE2XGR/1


On Fri, Nov 20, 2009 at 10:49 AM, Andy - KU4XR <ku4xr at yahoo.com> wrote:
> Hi all:
>
> I hope soon to rewind my LOWfer antenna coil with the #14 soild,
> in place of the #28 I'm using now. DC Resistance will be lower,
> which in itself will be another improvement in the overall setup.
> I'll be using a white paint bucket this time, and probably a
> white, thin walled PVC for the vari-coil, 4" diameter.
> To this point, I have been concentrating on antenna, but now I
> need to begin educating myself on optimum coils, and winding.
> I admit right up front that my experience in this area is just
> starting.
> I do not want to cut the #14 wire " too short " , so I need to
> know how to calculate the number of turns needed for a particular
> Inductance. I also don't want to cut it way too long, as this will
> be waste.  And, for my education, if the inductace needed for #28
> wire is 2.36 mH at resonance, will it be the same for #14 wire ??
> That will help me to know this too.
> Any help you gentlemen will offer will be most appreciated.
>
> Thank you and 73 to all :::
>
>
> Andy - KU4XR - EM75xr - Friendsville, TN.
> LOWfer Beacon " XR " @ 185.29866 KHz ( QRSS-60 )
> Coordinates:  N:  35* 43' 54" - W:  84* 3' 16"
> http://www.myspace.com/beaconxr
>
>
>
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