Noise Measurements in the UHF Range (Abstract)

Comparative noise figure measurements in the 400 mc frequency range have been made using commercial noise diode sources, thermal noise sources, and fluorescent lamps as noise generators. The thermal sources were of two kinds, a high temperature source at about 1,000°K and a low temperature source at 4°K. Measurements made with noise diodes yielded results about 1.0 db higher than those made with the thermal noise sources, from which it is inferred that the diodes are not satisfactory primary standards of noise in this frequency range. The effective noise temperature of a standard 6 w fluorescent tube (coupled to a helical line) was determined to be approximately 12,000°K by comparing its noise output with that of the hot thermal source. This is consistent with the figure of 11,400°K reported by Mumford at 4,000 mc.