>You will also need an accurate clock to calibrate them against,
>probably using a thermostated oscillator.

In the US it is much easier to use WWV or WWVH at 5, 10, 0r 15MHZ. A good
way to estimate rate of change is to look at the WWV audio "beep" with your
scope, and trigger the scope with a one-second timing signal from your
circuit. Use the expanded-sweep feature of your scope to magnify the rate
by 10X.

Reg



.....................Reg Neale.....................
"Ignorance is a renewable resource"   P.J. O'Rourke