Abstract :
Lightning discharges are known to occur within the cloud, from cloud to air, from the cloud to ground and between clouds. In the studies of atmospheric radio noise and characteristics of thunderstorms, an instrument is required for recording all the types of lightning flashes mentioned. The paper describes such an instrument and its tropicalized enclosure. The instrument is an extension of the Aiya noise meter and employs identical calibration and test procedures, but is completely transistorized to make it portable. It is triggered by the HF radiation field arising from lightning flashes. To reduce production costs as well as to facilitate fabrication of the instrument anywhere, the design has been based on the use of ordinarily available and commercially mass produced components and devices. The instrument operates from a 15v-battery supply, drawing 10 ma normally and about 35-40 ma when registering a flash. The exact operating frequency, bandwidth and sensitivity are capable of adjustment to desired values over a wide range. Two flashes occurring at an interval exceeding 1.5 sec can be resolved by the instrument, and this is adequate on the basis of available information.
