Ralph Mowery: watching many hours of RTTY with only 170 hz between the tones, I have seen one tone fade and come back in several seconds, then the other tone will do the same thing.
It sounds like selective fading Ralph. You can often see this in the waterfall of wide modes like MT63. The selective fade "notch" will sometimes move slowly accross the spectrum. My best guess is that despite the narrow 170hz bandwith, this type of fading could take out one RTTY tone for several seconds before it recovers to move on and take out the other. Tony KT2Q
