After referring to unsuccessful attempts based on a wafer-type mount, a coaxial unit is described which operates over the frequency band 26-40 Gc/s, and is mechanically interchangeable with American crystal 1N 53. The new crystal employs a silicon point contact of high sensitivity, and the mount was designed to give best v.s.w.r. over the entire bandwidth.The design technique is described in detail and experimental data are summarized. Notwithstanding some difficulty in manufacturing to the required sensitivity, a broad-band design has been achieved and the capabilities of Q-band detector crystals have been gauged.