The 13PD75LDC-ST, an InGaAs photodiode with a 75mm diameter photosensitive region packaged in a TO-46 header and aligned in an AT&T ST active device mount, is a low-darkcurrent version of the 13PD75-ST intended for high speed and low noise applications. The diameter of the photosensitive region is sufficently small to enable operation at low dark current and low capacitance while offering efficient coupling to multi-mode fiber. Reliability is assured by 100% purge burn-in ( 200oC, 15 hours, Vr = 20V ), planar semiconductor design and dielectric passivation. The ST receptacle is suitable for bulkhead and PC board mounting.