The Model 1124A Probe provides high voltage, high impedance, general-purpose probing capabilities for 50-ohm input, high frequency instruments. The probe input RC, 10 megohms shunted by 10 picofarads, prevents circuit loading while a FET (field-effect transistor) circuit provides a bandwidth of dc to 100 MHz. A wide dynamic range, provided in two ranges (X10, X100), allows direct measurements up to 100 volts with either ac or dc coupling. The maximum safe input for the X10 range in the dc-coupled mode is ±300 volts (dc plus peak ac) for frequencies below 100 MHz. The X100 range extends the maximum safe input to ±500 volts (dc plus peak ac) for frequencies below 100 MHz. The maximum safe input in the ac-coupled mode is the same as for the dc-coupled mode except the dc component of the input signal must not exceed ±200 volts. Figure 1. Model 1124A Probe 3. The Model 1124A Probe extends the usefulness of 50-ohm systems such as Hewlett-Packard 183A oscilloscope systems or the Hewlett-Packard Model 8553B/8552A Spectrum Analyzer system by adding general-purpose