8753/8720 cal kit TRL class mappings

The "D" and "E" models of the 8753/8720 network analyzer family appear to have 15 standard classes, including three for TRL calibration.  However, this is misleading.  The analyzers actually keep track of only 12 classes, and the three TRL classes are "mapped into" the others.  This means that if you modify the standards assignment for the TRL Reflect class, for instance, you will find that the S11A and S22A classes are also changed.  If you modify the class label of the S11C class, the label for the TRL Line or Match class also changes, and so on.  The bottom line is that you cannot independently specify the 12 SOLT classes and the three TRL classes.

This should not be a problem, since it is unlikely that anyone would need to design a cal kit for both types of two-port calibrations.  Normally a kit would be for either SOLT or TRL, but not both.  If you did try to make an all-purpose cal kit definition for these network analyzers, you might find it most frustrating.

This restriction does not apply to the 8510 family, where all of the classes are completely independent.