A transportable hydrogen maser for Australia Telescope

To equip the Chinese VLBI network, a transportable compact active hydrogen maser has been developed at Shanghai Observatory (SO) since 1985. So far five such masers have come into use for VLBI radioastronomy and some military. These hydrogen masers are all compact, relatively light, rugged and easily transportable. Including the electronics system, power supplies and stand-by batteries, their size is 57 cm/spl times/83 cm/spl times/127 cm and their mass is not more than 300 kg. In Nov. 1993, one of these masers was transported to Australia Telescope National Facility (ATNF) to determine its performance as a stable oscillator for VLBI. This paper describes the design and construction of the hydrogen maser and presents the results tested at Parkes Observatory of ATNF.