The 5950 Crystal Impedance Meter is used for measuring directly the resistance and oscillatong frequency of quartz crystals under either series-resonant or antiresonant conditions. The instrument is comprised of a main frame, with power supply, metering, and logic circuits, into which either of two plug-in rf modules may be inserted (sold separately), depending on the frequency range desired. Sensitivity controlled via a three-position switch allowing Low-Medium-High sensitivity.