Roy Lewallen wrote:
Multiplying the two original signals of 1500 and 1955 generates the two
new frequencies of 455 and 3455, for a total of four frequencies after
multiplication. Adding them wouldn't do it.

Part of the confusion is that audio engineers talk about "mixing" where
they actually mean adding. Mixing - as RF engineers use the term - is
precisely what they don't want!


--
73 from Ian G3SEK 'In Practice' columnist for RadCom (RSGB)
Editor, 'The VHF/UHF DX Book'
http://www.ifwtech.co.uk/g3sek