Disclaimer and Apology


This is a shameless rip-off of George Murphy's (VE3ERP) fabulous HamCalc v. 9.4. Get the original if you want to see some nifty DOS-Basic programming. Lacking a full-time DOS machine, I've been forced to convert a tiny fraction of his massive collection. I originally built Excel spread-sheets, but they lack the polish of an application program. I found that Java worked much better, and also permits web publishing.

The original works wonderfully in Metric or American units. I haven't attempted to make this program capable of arbitrary units on display. This is strictly in American units.


There are two major, known compatibility issues.

  • AOL. The AOL web browser doesn't understand Java. If the pages don't have calculators on them, your browser doesn't understand Java. You'll have to either get the original HamCalc or get a better browser.
  • Internet Explorer 4.0. The IE 4.0 browser's Java is not standard, and doesn't seem to work correctly. Also, IE 4.0 cannot be uninstalled, and has made irrevocable changes to your Windows 95 system. Sorry. Additionally, you may suffer kernal32.dll crashes, games that use DirectX 5 may stop working, Windows 95 may freeze up when the channel screen saver is used, you may not be able to use certain video cards in true color mode, you may have problems with Microsoft Outlook 97, you may lose profiles in Outlook and Exchange.

Problem Resolution

Problems, questions, complaints, etc. to S_Lott@yahoo.com

Fine Print: This software has no warranty of fitness for any purpose whatsoever. If it doesn't seem to "work", I may be sorry, but I am not liable in any form. I will do my best to make such repairs as I see fit.


List of all HamCalc Modules


This is built with a Java applet based on my own Model class. A Model represents a mathematical model and includes fields which represent variables of that model. A Model can compute any one field given values in one or more other fields. Each field is dependent on zero or more other fields. A field which depends on zero other fields must be entered can cannot be computed. Other fields will be computed as data is entered.

As an example, consider the RTD model: rate*time = distance. We can solve for either of the other two: r=d/t and t=d/r. The model knows all three formulae and picks one based on the order of the user's of inputs.

As a usability note, Java does not recognize TAB as a significant GUI action. It's just another character. Return or Enter are GUI actions. I could (and perhaps will) change this in the future. For now, you must click on the field, enter the data, and either hit return or click on another field to see the calculation. Also, your JVM may not handle color changes correctly.

As you enter values for fields, the model checks all other fields to see if they can be computed from the fields available. Fields you enter are marked in <FONT COLOR="#0000FF">blue</FONT>, fields it computes for you are marked in <FONT COLOR="#FF00FF">magenta</FONT>.

Generally, the model uses a least-recently-used algorithm to determine what is computable. If you enter rate and time, it computes distance. If you change either rate or time, it recomputes distance. If you change distance, it recomputes whatever you entered earliest.

For example, enter rate, enter time, get distance; change distance. Since rate is least recent, it will be computed from time and distance. The colors will change to reflect this.

Some web pages have multiple models. When there are two (or more) models in the same panel, fields with identical names will be copied down the panel from a model to the model below. You can change these in subsequent models, but the change will not ripple back up the panel to prior models.

Some models are fairly complex, and have several variables with complex relationships. An example is the air coil design. A typical scenario for coil design proceeds as follows.

  1. Use the AWG-Diameter-Turns-per-Inch model to choose your wire. Adjust the TPI or the diameter to allow for enamelled wire (0.005&quot; insulation). If using insulated wire, wrap a ruler, measure and enter turns per inch.
  2. Enter the inductance (in &micro;H's) for the coil. The form computes an ideal coil diameter and number of turns.
  3. Adjust the coil diameter for materials on hand.
  4. Adjust the number of turns to be an integer -- the inductance and length/diameter ratio will be recomputed to show you how your actual coil will match the ideal coil.

Note this common problem: If you do not change the coil diameter, the recomputation of iductance will not be completed. Manual entry of both coil diameter and number of turns (as well as TPI) is required to compute inductance. The computed (in <FONT COLOR="#FF00FF">magenta</FONT>) value is not sufficient, you must enter a value to make the field turn <FONT COLOR="#0000FF">blue</FONT>.

List of all HamCalc Modules

This is the complete list of HamCalc v 9.4 modules.

  • 555 Timers, see 555 One-shot Timer and 555 Multivibrator (Oscillator)
  • A.C. Circuit Calculator
  • Antenna Length calculator, see Antenna Length Calculator
  • Attenuators: Pi-Net & T-Sect., see Attenuators
  • Audio Bandpass Filter
  • Audio Tone Analyzer
    1. &amp; W. Air-Core Inductors
  • Band-Reject Filter
  • Battery Schedule
  • Calendar
  • Capacitor Design Calculator
  • Capacitor - Custom Value
  • CCD Antennas
  • Circle - properties of
  • Clock Screen Saver
  • Coaxial Cable Characteristics
  • Coax Traps for Multi-Band Antennas
  • Code Practice
  • Coil Designer, see Air-Core Single-Layer Coil, revised 7/21/97.
  • Coil Equation Calculator
  • Copper Wire Tables and Calculator, see Diameter-AWG #-TPI
  • Decibel Calculator
  • Decimal/Fraction Converter
  • Equivalent Units of Measure
  • Great Circle Paths &amp; Distances
  • Guy Wires for Antenna Towers/Masts
  • HAIRPIN Beta-Match for Yagis
  • Ham Shack Stairs
  • Helical Resonators (shielded)
  • Helical Windings
  • Impedance - series/parallel ccts.
  • Inductors - Dryer Vent Hose
  • Inverted Vee Antenna Dimensions
  • L/C Network Tuned Circuits, see L-C "Tank"
  • LED Series Resistor
  • Line-of-Sight radio wave
  • Local Repeaters
  • LOG-YAG log-periodic Yagi antenna
  • LM317 Voltage Regulator
  • L-Pad Impedance Matching
  • Matching Networks for Transistors
  • Metric Conversions
  • MINILOOP miniature loop antenna
  • MINIQUAD coil-shortened antenna
  • Mobile Whip Antenna
  • NiCad Battery Discharger
  • Ohm's Law Calculator
  • Open Wire Transmission Lines
  • Parabolic Antenna
  • PI-Network Impedance Matching
  • Potentiometer - Custom Value
  • Power Supply Design
  • Prime Numbers
  • Q Calculator - Resonant Circuits
  • Quad Antenna Dimensions
  • Quadratic Equations
  • R/C Time Constant
  • Resistor - Custom Value
  • Resistor - Precision
  • Sag in Horizontal Wire Antennas
  • Satellite Orbit Parameters
  • Series &amp; Parallel components
  • Series-Section Balun Transformer
  • Short Dipole for restricted space, see Short Dipole Antenna
  • Speed/Time/Distance calculator, see RTD_Statute and RTD_Nautical
  • Stub Match for Antennas
  • Sunrise/Sunset calculator
  • SWR (Standing Wave Ratio)
  • Telescoping Aluminum Tubing
  • Toroid Antenna Traps
  • Toroid Inductor Calculator
  • Triangles - trigonometry
  • Transformer ratio calculator
  • Transformer Winding Calculator
  • Transmission Line Losses
  • Transmission Line Performance
  • Trimmer Capacitor calculator
  • Trap Dipole Design
  • Zener Diode Voltage Regulator

© 2005, 2009 Steven F. Lott

Version: 2
Updated: 1997
Made: 2009-05-20 17:28:00.065251
Webmaster: s_lott at yahoo.com