Special symbols turn into "?"

I normally use Netscape Communicator to edit my HTML documents. But when I write about phonetics, in order to insert phonetic symbols, I edit the HTML source (with Notepad) in order to use Unicode devices like "[ampersand][pound sign]601[semicolon]" for schwa, etc. When I save the HTML source and view it with Mozilla Firefox, everything is okay.

BUT -- if later I go back to editing the document with Netscape, and save it, the Save action turns all the hard-earned special symbols to question marks. Argggh! How can I avoid this?

Lee H.