Cap't - frequency and "duty cycle" are NOT the same. Think of turning a light switch on/off. Duty cycle is the percentage of time the light is on versus off and frequency would be the time from when you first turned it on, then turned if off and then on again. The second time you turned it on would be the end of the first "frequency" cycle. If you did the complete "cycle" in one second with 40% of the time the light is on and 60% of the time it is off that is 40% duty cycle. That's a good explanation for a mechanical engineer isn't it. Just go get a high quality Fluke with duty cycle capabilities and you will not go wrong.