A 500-volt pulse transmitter for ice sounding

A high-voltage pulser developed by the U.S. Geological Survey for glacier soundings is a small battery-operated unit that weighs about one kg and was packaged in a case measuring 8.2 X 12 X 18.8 cm. It operates from an external 12 volt battery and supplies a 500-V pulse to a dipole antenna. The waveform changes shape only slightly for antenna impedances ranging from 20 ohms to thousands of ohms. Shunting a resistive load of 200 ohms with a capacitance of hundreds of pF causes only a very small rounding of the leading corner of the pulse. The pulse-rise time to the full voltage is about 100 nS and fall time to zero is about 150 nS. The 10 to 90-percent rise time is about 60 nS. The total pulse duration is adjustable from about 250 nS to about 1200 nS. Pulse-repetition rates range from 1000 to 10,000 pulses/sec. Maximum battery drain of 3 A occurs at the maximum repetition rate, and is less than 1 A at minimum-repetition rate.