A pump experiment of two astronomical heterodyne receivers, a superconductorinsulator-superconductor ͑SIS͒ receiver at 450 GHz and a hot-electron-bolometer ͑HEB͒ receiver at 750 GHz, is reported. A low-temperature-grown GaAs metal-semiconductor-metal photonic local oscillator ͑LO͒ was illuminated by two near infrared semiconductor lasers, generating a beat frequency in the submillimeter range. I-V junction characteristics for different LO pump power levels demonstrate that the power delivered by the photomixer is sufficient to pump a SIS and a HEB mixer. SIS receiver noise temperatures were compared using a conventional solid-state LO and a photonic LO. In both cases, the best receiver noise temperature was identical ͑T sys = 170 K͒.