I just got the Tutor Meters C-100 instrument as well. I'm using it to check the output of modulators in a cable headend. So far, I'm very pleased. It has helped me to adjust the RF output, and I am intending to use it for balancing the modulators and for balancing the audio/video outputs of each one.
One curious thing about it is that when I tried a voltage check, it registers no voltage (0.00) on the cable. I may be looking for the wrong detail or something, but that did seem unexpected.