You are both right.

On a 1966 issue of QST magazine, I found the advertisement of "Echoplex" by Kahn
Research Laboratories. It sold for more than 300$, which was not cheap at those
times.

As to Lincomplex, I remember a friend of mine working for Page Europe who told
me having installed Lincomplex on HF transmitters in Africa.

73

Tony I0JX
Rome Italy