The 85081A is a high-impedance input module with a frequency range of 100 kHz to 1 GHz for use in the 8508A vector voltmeter. The 8508A /85081A form a two-channel receiver that make high frequency voltage measurements easy. A narrowband measuring technique gives it a sensitivity of 10 uV to help you measure even the smallest signal. The 8508A also measures the phase between two signals - so you can use it for another complete set of measurements - like group delay and electrical length. The 11570A accessory kit allows measurements in a 50 ohm Type N coaxial system.