Hello, i need to drive the inner shield conductor of a triaxial cable in order to avoid the effect of cable capacitance (phaseshift of signal). Signals will be 1to 5Vrms and frequency between 1Hz and 250kHz. Since i'm quite a newbie i tried to build the guard with a OP27 in follower configuration. Unfortunately @67kHz and Signalamplitude of 1Vrms the circuit is unstable... amplifiers are ocsillating. My question: Is there a pincompatible alternative for OP27, which can drive my shield properly. BTW: cable capacitance is about 150pF/m. I thought about Buf634??? Many thanks for your help!