Here is a small collection of .xlsm files, ZIPped for easy download.  These files are the work of Joe Gorley, a long time SWL and mad keen Excel user.   If you want to know what they do, download them and find out.  The average file size is just a few kb and download time is a few seconds.   Simply click the name (green text) below to download the file or, click on any image to open a larger view in a new window.
 

1.) Shortwave		2.) Toroids 5 parts in 1 workbook		3.) Op-Amps
4.) Tower Calculations		5.) Inductance		6.) Reactance
7.) Wire Sizes		8.) Meters		9.) Resonance
10.) Vectors		11.) Navigation		12.) Transistors
13) Antenna Calculations contains 12 sub-programs for calculations on various antenna configurations of which the demo image 'Parabolics' is just one.		14) Timings		15) Decibels