The DOS software you are refering to might be RF Tools, from Teledyne. It
calculates attenuator values, Xc, Xl, resonant frequency, etc. If you do a
search for RF Toolbox, you should be able to find the zip file. If you
need
a copy, let me know.

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The trouble with software calculating tools is one doesn't know whether one
has the correct answer or not. Rubbish in - rubbish out!

Nothing can replace an understanding of what is to be done and a pocket
calculator.