[Boatanchors] SSB ***WITHOUT SUPPRESSED CARRIER***

[sdaitch at ibb.gov]

I could not find the original message that referred to SSB with reduced carrier for recevier control purposes, but let me add a little to that in a practical operation.

In the old days when VOA ran the SSB/ISB transmitters for program feed, our standard was for the carrier to be about 20 dB down from the nominal peak power output.  On the TMC GPT-40K SSB transmitters at Greenville, we ran about 200 watts carrier power.  

Our receivers, RCA SSB-3 series, at the receiver sites (now all long gone), had a carrier frequency filter and amplifer circuit that drove an AFC circuit to keep the receiver locked on to the carrier frequency.  That way, all the audio was exactly on frequency.  This AFC was electromechanical, not unlike that in the CV-157 SSB convertor, in that the AFC error signal drove a motor coupled to a variable capacitor, which changed the receive frequency.  I can't remember if the cap actually changed the frequency of the master oscillator, a Collins PTO, or another LO in the system.  Don't have the book with me to answer it definitively.

Now that we have no receivers with AFC, I suspect if we ever were to run a TX in SSB, it would be with suppressed carrier, not reduced carrier.

73
Sheldon
WA4MZZ