Hmmm... nothing wrong with my email. I've been getting emails today and my in box is not full. Anyway...
I have never used a scope. I've only used my DMM, which does happen to have a frequency counter function, to calibrate the ADA. But I think you can actually get pretty damn close doing it by ear, too. (I know some folks will probably disagree with that. But if they chime in, you'll have their advice to consider, too. Cool, huh?) So, just go back and forth several times, set the high point of the sweep and then the low point of the sweep, then go back and check the high point again, then the low point again, over and over and so on... until you are happy with how it sounds. I think you'll find that you will either max out the extent of the sweep at one or both ends, or the sweep will go so far at one end that the sound of the effect will sort of get lost. In that case, just dial it back until you are happy with the sound.
~ Charlie