Random Sampling Oscilloscope for the Observation of Mercury Switch Closure Transition Times

With the advent of new miniaturized mercury (Hg) switches with reputed transition times of the order of 10 ps, interest has been rekindled in their use in high-peed pulse measurements. Since there is no pretrigger signal available from a Hg switch, normal sequential sampling techniques are not useable to measure the fast Hg switch transition time. For this reason, a new random sampling time base unit was designed to perform these measurements at the low repetition rate of Hg switches. The time base may be used with commercial sampling oscilloscope systems through suitable interconnection terminals or possible interface equipment. It features three selectable time windows of 1 jus, 100 ns, and 10 ns. Using its time magnifier, the fastest sweep rate is 10 ps/cm. A variable trigger lead time control is provided. The trigger sensitivity is 5 mV.