On-line RF calculators

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**k4kyv**:

Here are some free on-line calculators I have found useful while working on designs for my revised antenna tuners.

Coil inductance calculator: http://www.66pacific.com/calculators/coil_calc.aspx

L-, Pi and T- networks: http://www.changpuak.ch/electronics/calc_18.php (copy and paste into browser)

Inductive and capacitive reactance calculator: http://www.daycounter.com/Calculators/Reactance-Calculator.phtml

The drawback with these is that they work only one way. For example, you enter the number of turns and dimensions of the coil and it calculates the inductance. You enter the frequency and inductance or capacitance, and it gives the reactance. To find the number of turns to achieve a given inductance or to find the capacitance or inductance needed for a given reactance, work backwards and calculate by trial and error; keep entering numbers to narrow down the turns, capacitance or inductance until you hit the target figures. Still less tedious and time-consuming than working out the equations long-hand according to the formulae in the Handbook.

**KC2ZFA**:

I really like this one:

http://hamwaves.com/antennas/inductance.html

**W4NEQ**:

Quicksmith isn't online, but it's free and allows you to construct reasonably complex matching networks, provides numeric and Smith chart output, and allows you to increment or decrement values to play "what if" or to "walk in" your match. I've used it for years and it works well.

http://www.nathaniyer.com/qsdw.htm

Chris

**W4NEQ**:

Here is a screen capture of Quicksmith. The arrow buttons adjacent to the network components on the right side let you "what if" the values into your match. It installs easy without big mess.

**AL7FS**:

You may with to check out SimSmith.

http://groups.yahoo.com/group/SimSmith/?yguid=124226559

SimSmith is a Smith Chart CAD software package. Written in Java, SimSmith runs on Window XP, Windows 7, Apple OSX and Ubuntu. It uses the JRE-1.6 runtime environment.

SimSmith is unique in several ways: it has only one screen which can be scaled to any size display, it allows any number of circuit elements, it allows the algebraic expression of circuit elements, it models transmission line losses, it allows 'load files' to be imported from antenna analyzers and antenna simulation programs.

SimSmith circuits can be saved and shared between users.

This group provides a medium for sharing circuits, techniques, feature requests and feature announcements.

SimSmith can be downloaded from www.ae6ty.com/Smith_Charts.html

73, Jim, AL7FS

Anchorage, Alaska

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