[SOC] Need formula

[Hank Kohl K8DD]

At 5/21/02 03:39 PM -0600, you wrote:
>Can anyone tell me the formula to figure the inductance of an air core
>coil with spaces between the turns?  I can't find it in my handbook
>(probably not looking in the right place), and the only online
>calculation deals I can find don't account for spacing between the turns.
>
>72/73/oo
>Rob, w0jrm-

"The approximate inductance of a single-layer air-core coil may be 
calculated from the simplified formula:

                    d squared * n squared
L (uH) =     ------------------------------------
                  18d + 10l

where:
L = inductance in microhenrys
d = coil diameter in inches
l = coil length in inches
n = number of turns"

"To calculate the number of turns of a single-layer coil for a required 
value of inductance,

                square root (L (18d + 10l))
n =          ---------------------------------------
                                 d

 From the 1985 ARRL Handbook, page 2-11

73    Hank    K8DD