
			     Installing the Program

	COIL is a Windows console program. Double-click on COIL.EXE,
right-click on the title bar, and select Properties. Under Options, uncheck
QuickEdit Mode. Under Font, select a font and size.

	To position the window, drag it by the title bar to where you want it
on the screen. Right-click on the title bar, select Properties, then Layout.
Click OK.


				    Details

	Click below green, blue, and purple for details about each panel.
Click above the panels to show the program version.


				   Litz Coils

	Too many strands in the lowest-level Litz bundle can degrade Q. COIL
displays a conservative limit. You can exceed it if radial strand position
varies randomly enough along the bundle. See COILS.TXT for examples. To be
certain, observe the limit. Bundling more than five sub-bundles can be unstable
and lead to an arrangement with lower Q. COIL does not model Q degradation due
to too many strands or sub-bundles. See COILS.TXT for examples of coils that
suffer from these issues. To ensure RF resistance accuracy, COIL inhibits
calculation if strand diameter is greater than skin depth.


				    Optimizer

	The optimizer varies selected coil parameters to maximize Q while
keeping inductance constant. If you optimize wire gauge, the result will be a
non-integer value displayed in gray. Enter it to use the integer value. Then
adjust another parameter to restore the original inductance and reoptimize
without varying the gauge.

	To simplify an optimized coil, set the number of turns to the nearest
integer, adjust another parameter to restore the original inductance, and
reoptimize without varying the number of turns. This degrades Q very little.


				    RLC Model

	COIL provides results as an inductance in series with a resistance. Due
to self-resonance, the inductance value varies with frequency. When using
single-frequency results over a frequency range for circuit or antenna
analysis, accuracy may be inadequate.

	COIL can provide results with a parallel capacitance. Inductance and
capacitance for this model vary little with frequency. Resistance varies as the
square root of frequency due to skin effect. Inductance and resistance variation
increases with form loss, wire loss, and lead length.


				      Leads

	COIL models radial leads as a lossy transmission line. They can have
any length. COIL models axial leads using self and mutual lead inductance,
interlead capacitance, and lead resistance. Accuracy for this lumped-element
model should be fine for leads of ordinary length, but it will degrade as leads
lengthen. For centered axial leads, add the coil radius to the straight length.


				    Coil Form

	Dielectric normally begins at the inner wire surface. For a form with
grooves or slots, click on Form Thickness for Grooved Form. Dielectric then
begins at the wire centerline.

	Form contact is the percentage of wire in contact with dielectric. Use
less than 100% for dielectric ribs, ridges, or open frames. Double the value
and use a grooved form if dielectric extends outside the wire, as for Air Dux
or slotted tubes. Increase the value to account for nearby dielectric not in
direct contact, as for ridges or slotted tubes.

	For Air Dux or slotted tubes, use the dielectric radius as form
thickness. Then use a grooved form and double the form contact value to
account for all of the dielectric.

	For a polygonal coil with truncated vertices, measure the perimeter
and multiply by these values to get the equivalent untruncated diagonal:
octagon 0.327, hexagon 0.333, square 0.354.


				   Calibration

	To recalibrate the results, create text file CAL.TXT with up to four
values. The first two are inductance and resistance calibration factors for
solid wire and the last two are for Litz wire. Default values are 1. This
example leaves solid wire calibration unchanged, increases Litz inductance,
and decreases Litz resistance:

1 1 1.01 .99


				      Tips

	Keep Freq/SRF < 0.6 for best accuracy.

	Reenter inside or outside dimensions after changing wire gauge.

	Enter 1-31/32 instead of calculating and entering 1.96875.

	Given 420/46 Litz, enter 270/ for 270/46 or /48 for 420/48.

	Q degradation due to typical 0.04 mil tin plating is negligible at HF.

	To design an inductor using coil stock, use turns/inch or turns/cm and
adjust coil length with the mouse wheel to obtain the required inductance.

	DOS keys still work. Use Home and End to change form material, up-arrow
and down-arrow for data entry, PgUp and PgDn for wire metal, and Esc to exit.


				 Latest Version

	Check the version number in the link at the bottom of this page:

http://ham-radio.com/k6sti


				   References

Inductance
http://g3ynh.info/zdocs/magnetics/Solenoids.pdf

Resistance
http://g3rbj.co.uk/wp-content/uploads/2013/08/The_HF_Resistance_of_Single_Layer_Solenoids_2.pdf

Self-Resonance
http://g3ynh.info/zdocs/magnetics/appendix/self_res/self-res.pdf
http://g3rbj.co.uk/wp-content/uploads/2020/02/The-Effect-of-dielectric-inside-a-coil-iss2.pdf

Litz Coils
https://engineering.dartmouth.edu/inductor/papers/litzj.pdf
http://thayer.dartmouth.edu/inductor/papers/SimpLitz.pdf
http://litzwire.com/nepdfs/Round_Litz_Catalog.pdf