[Radio Wrangler]

There were systems using reduced carrier power as a pilot tone for PLL receivers to lock onto. DSB, SSB and ISB modulation were all used.

I used to use a Redifon GK203N synthesised exciter unit as my HF transmitter (with an RA117 receiver). The Redifon's mode switch had several reduced carrier AM modes on it which I never used.

I also remember, in an old Shortwave Magazine, an article on a self-clarifying ssb adaptor. I can't remember the year of the magazine. The adaptor was valved. I can't remember whether it tried to find a bit of residual carrier or whether it tried to align audio harmonics, though I think it was the latter. It was a magazine on loan to me, so that would have put it in the middle 1950s to middle 1960s era. I'd expect that the author must have been someone doing such things professionally.

Editors don't dare put anything like that in their magazines nowadays. They have an ethos which asks "Will enough people build one?" when back then editors asked themselves "Will anyone learn anything from it?"

David