AIR CORE INDUCTOR WINDING THE EASY WAY.
Air Core Inductor Winding The Easy Way
The following information for winding RF coils is accurate to within 1% for nearly all small air core coils, where:
L = Self Inductance in micro-henrys.
N = Total number of turns.
r = Mean Radius in inches.
l = Length of coil in inches.
b = Depth of coil in inches.
You can make small adjustments to the inductance by spreading the coil turns to some degree to tune your circuit. Also the larger wire sizes will improve the “Q” or quality of the coil and of course reduce the DC resistance of the coil.
This information is Courtesy of ALLIED’S RADIO HANDBOOK.