Mike -- Typically I've had the most success on 15 between 21.390 and 21.425. If 425 is busy, I wander down towards 390 and find a clear frequency. I know I've done AM above 430, but not much if I recall. 390 Seems to be an unofficial secondary calling frequency.
I typically don't wait for an AM QSO to end; I just go find a clear frequency. The caveat emptor is if I'm working around the shack and need some noise, or if the in progress AM QSO is about to end. I'm off work the last weekend in December, so will be doing a lot more 15 AM (and hopefully 10M too) during that time. 73 Mark K3MSB
