"Focal Length Calculator"
"A.C.H.2"
"To use the Focal Length Calculator, you must know the diameter and"
"depth of your dish, in inches.  The screen shows the calculated focal"
"length and the f/D ratio.  The calculator will halt with an error if"
"zero is used, so it starts with a ficticious dish, 120 x 25."
"Your dish antenna is a reflector, reflecting the microwaves back at the"
"feed assembly.  Enter the diameter and depth of your reflector by typing"
"the amount, followed by the ENTER key.  If you press the ENTER key"
"without typing an amount, the previous amount will be retained.  When"
"the ENTER key is pressed, the entry field moves from diameter to depth"
"and vice versa.  When the ENTER key is pressed while the entry field is"
"under Reflector Depth, the amounts for diameter and depth are calculated."
"The new focal length and f/D ratio is displayed above."

