A word of caution. One can find the fastest match or one can find the best match. I suspect the two are not the same. It is possible for a tuner to have multiple combinations of L and C where a low SWR is produced. However, only one of these solutions is likely to be the most efficient. K6JCA did a lot of work creating his own 500 watt tuner. In Part 9 of his 10-part article he discusses finding the best return loss (lowest SWR) while obtaining a reasonably efficient match. His entire article is a trove of information about how an antenna tuner should be designed. One part I found particularly interesting was the section on inductor and capacitor selection.
Fortunately he defines his search algorithm in detail. One of my (many) complaints about "free" software is that it is poorly documented. I'm not complaining, but it is unfortunate that the ATU firmware archive does not include documentation on how it works. A flow chart would be very useful in order to quickly see how the algorithm works. It's simply not possible to compare dozens of pages of programming code to easily see how two different systems work!
Perhaps, someday, I'll sit down and struggle through the C code and convert it to an easy-to-understand specification.
My main point is that the efficiency of the final match needs to be considered, otherwise we are probably best sticking with what seems to work reasonably well. One last point. Poor efficency means that the power is going somewhere, just not into the antenna. That usually means higher voltages and currents within the tuner which then dissipates energy in the form of hot components.
73,
Chris, K9EQ
