Now your getting it. And yes they do use SSB. I did have a quack before I regulated the oscillators. Even now a very strong signal can cause it. It is from loading which might cause the oscillator to shift, either the BFO or even one or both LOs because they must maintain a particular offset to sound perfect. So even if you use PLL and the BFO is free running, excessive loading from say the audio, will cause the "quack"...lol. But hey, you should love it. You would think if anybody could understand it, it would be Scrooge McDuck.