I don't know about a site, but there are programs in BASIC in various
books - "AMATEUR RADIO SOFTWARE" by John Morris GM4ANB springs to mind
(may still be available from RSGB) which covers the subject and has
listings ready to type in.
if you feel itch on your skin when hearing the word BASIC, I have a C
does the Maidenhead -> LatLong conversion, which I have used in Spectran.
I am not the author of the code, I found it on Internet, but don't
But it works !
73 Alberto I2PHD