Active H-Masers for V.L.S.I. Applications

Summary Three active H-masers have been manufactured at L.H.A. for french radioastronomers and geophysicists. They are transportable and compact. Including electronics, power supplies and batteries, their volume is about 0.5 m3 and their mass is 280 kg. They are operated from 220 Vac or 24 Vdc power supplies, and their internal battery makes it possible to operate them during transportation. Signal receiver and phaselocked loop have been designed to optimize the frequency stability transfer. Operating conditions are microprocessor controlled and monitored. Measurements of the short term frequency stability, and of systematic effects are presented.