The Master Experiment

A wideband low noise preamplifier system will be utilized for the A TS series of satellites at the Mojave Tracking Station. This particular preamplifier was developed by the Advanced Development Division of Goddard Space Flight Center, and involves a travelling wave maser and a closed cycle helium refrigerator. It operates over the 4.065- 4.195 gigahertz (Hz) band, with an effective noise temperature of less than 10°K, The functional maser system consists of the amplifier, a low noise header assembly, and a super conducting magnet. The antenna mounted support equipment includes the microwave pump, pump modulator, pump monitor, transfer switches , tunnel diode amplifier , and a noise source, as well as the closed cycle helium refrigerator . The major system components and their layout are shown in Figure 1. The scheme of operation is as follows: the signal from the antenna is passed through the header assembly to and from the maser by C- band waveguides , and to the post- amplifier by coaxial cable. In the maser, 27 db of amplification is achieved, and an additional 10 db is provided by the post amplifier. The equipment for controlling and monitoring the system is located in the Operations Building. Here are located the power supplies for all the components , with the exception of the closed cycle refrigerator, which is supplied with its own 440 v, 3-phase 10 kva supply di rectly at the antenna. The maser system performance characteristics are listed in Table I