A NorCal Project ...
by Dan Maguire AC6LA
Updated to version 2 on February 16, 1998
This is the (updated) set of BASIC programs mentioned in the article "RF Fun with the RF-1" published in the Spring 97 issue of QRPp, the journal of the NorCal QRP Club. Please feel free to re-distribute them as you see fit, as long as no money changes hands. I had fun writing them, and I hope you enjoy using them!
RF1CHAR - Walks you through the steps necessary to use the Autek RF-1 to determine the characteristics of a transmission line (velocity factor, characteristic impedance, dB loss values). Program information.
RF1RX - Converts SWR and Z readings made with the Autek RF-1 to R and jX values. Includes an error range of 10% (or 20%, depending on value) for SWR and 3% for Z, plus some hints on determining the sign of X.
ZIZL - Transforms R and jX values from one end of a transmission line to the other end, for a variety of real world lines. Works in either direction, input to load (shack to antenna) or load to input (antenna to shack). Also shows SWR, power, current, voltage, and dB loss numbers. Lets you easily play "what if" games with the values. Can show a continuous range of values along the line, either in tabular or plot format. Data file. Information.
VF - This one is almost too simple to be called a program. It lets you solve for any one of the four terms in the Velocity Factor equation without bothering to look it up and do the transform to get the term you want.
SWR - Another one that is just barely a program. Given an R and jX pair, and an optional line Zo (default 50 ohms), calculates total Z and SWR. Pretty simple, but sometimes you want to do this without bringing up a larger program.
ZMATH - Does math functions on impedance values. (Also works on complex numbers in general, remembering that A+Bi is equivalent to R+jX.) Data may be entered in any of five forms: R+jX, Z and angle, parallel Rp and Xp, capacitance (pF) and frequency, or inductance (uH) and frequency. Results are displayed in all forms. Functions include add, subtract, multiply, divide, square, square root, combine in parallel, remove in parallel, plus store/recall memory. (The "combine" function might be used to see what the result is of joining two lines going to two different antennas in a phased array. The "remove" function might be used to see what happens if a small amount of stray capacitance is removed from a measured impedance to get the "real" value. Both functions might be used (along with series add and subtract) to study the impedance transforms that happen in a typical C-L-C tuner from one side to the other.) Results are chained like a pocket calculator, in that the result from a previous action is used as the starting value for the next action.
LNET - This is a simplified version of the methodology given by Robert White, W6PY, in "The ARRL Antenna Compendium Volume 2." His technique lets you design any kind of matching system (PI, T, or L, high pass or low pass) based on a desired phase shift rather than the more common method of choosing a Q value. This stripped down program just does the calculations for a low-pass L network.
All of the above programs are supplied as .BAS files. They have been tested under BASICA, GWBASIC, and QuickBASIC. The package also include some .TXT user documentation files (including a README) and one .DAT file.
The following programs were contained in the original version of this software package but are now obsolete: COMPLEX (use ZMATH instead); ZPAR (use the 'c' function in ZMATH); ZCHAR (use RF1CHAR); ZMUTUAL (use ZMATH); ZFEED (use a scientific calculator or an antenna modelling program like EZNEC); and ZZSWR (use RF1RX).
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These pages are designed and maintained by George Heron, N2APB
Page last updated: June 20, 2003