The TS220 is a 50-ohm BNC feed-through terminator for the TS250 current monitor output termination. The TS250 Waveform Amplifier features a current monitor output on the back of the panel. It is recommended to terminate the current monitor output to 50 ohm. If your oscilloscope does not have an internal 50-ohm termination setting, you need the TS220 external termination. 50 termination is recommend for square-wave current waveform with fast rise time.
To monitor the TS250 output current, connect the current monitor output (BNC connector) to an oscilloscope input as show in Figure 1. If the oscilloscope already have a 50 ohm termination built-in, you don’t need the TS220 external termination. The TS250 current monitor output has a gain-scale of 100mV/A if terminated into 50Ω. If the TS250 output current to the load is 3A, the current monitor output is 300mV. Without termination, or the oscilloscope is set to 1MΩ input (high-Z), the monitor output voltage gain scale is 200mV/A. That is 600mV for 3A current. It is recommended use 50Ω termination for square waveforms or high frequency signals.
Figure 1 is a recommended connection diagram for Current Monitor using an oscilloscope. It is best to monitor current or voltage, but not both at the same time. If both voltage and current are monitored at the same time, it is recommended to leave the voltage probe ground lead unconnected as shown in Figure 1.
Figure 1. TS250 current monitor connection diagram.