850244 High Frequency Probe, The Keysight 85024A High-Frequency Probe is a passive probe designed for broadband RF measurements in a wide range of circuit applications. It provides a convenient method for making high-impedance measurements directly on surface-mount and microstrip circuits, allowing engineers to test RF and microwave circuits without disturbing the circuit operation. The 85024A is especially useful in design, troubleshooting, and system-level analysis in lab environments.