Well, then when i built my one - tube VLF receiver around 1963, this was close to the end of CW. I just wanted to try to nail down the date. I recall hearing what sounded like RTTY on telephone calls from Seattle to the Olympic Peninsula, ca. 1970s, and later, when driving to work late at night, at a certain dip in the road near Woodinville WA, where the AM station on my car radio faded, i could momentarily hear RTTY. No proof, but what else could it be ? This was less than 100 miles from 500 kW NLK.