We report on the gain bandwidth and noise characteristics of far-infrared mixers using high-Tc superconducting YBa2Cu3O7 (YBCO) thin films. The YBCO films are patterned into lattice-cooled hot-electron bolometers (HEBs) coupled to an integrated antenna and transmission line. Heterodyne and homodyne down- conversion using LO frequencies of 115 GHz and 585 GHz show a device conversion gain of as high as -9.5 dB at 66 K using 1 micro W of ...