I've built a calculator for Butterworth and Chebyshev crystal ladder
filter design, done as a Lotus 1-2-3 spreadsheet. This spreadsheet was
created on Lotus 1-2-3 Release 4, but is a .WK1 file (and associated
.FMT file).

The method used is from May 1982 QST, "A unified approach to the
design of crystal ladder filters", by Wes Hayward, W7ZOI, p. 21.

If you're interested, send me mail. I can send you a uuencoded .ZIP
file that's only about 6k bytes. If I get a lot of demand, I'll
see about uploading it to the think.com QRP archives.

Dan Halbert, KB1RT