The 1910A measures Frequency, Period, and Totalize…quickly and easily. In the Frequency Mode the range is 5 Hz to 125 MHz with ranges of resolution of 0.1 Hz, 1.0 Hz, 10 Hz and 100 Hz. Period Mode range is 5 Hz to 2 MHz. The input impedance is 1 MOhm shunted by less than 30 pF, AC coupled. Sensitivity is 15 mV rms at 5 Hz to 100 MHz and 25 mV rms at 100 MHz to 125 MHz. A front-panel attenuator switch is provided to decrease sensitivity by a factor of 10. Input is provided for external time base (10 MHz at 300 mV rms or greater into 1 kOhm). Display is a 7-digit LED with the number of units used and an overflow indicator.