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The Russian nuclear industry, which was centered primarily on Military operations and planning, developed a great diversity of specialized Geiger tubes for many different functions. The surplus SI-22G was one such tube. It measures 220mm (8.66 inches) long and 19mm (0.75”) in diameter. Because of its size and relatively low operating voltages (under 400), it is super-sensitive to Gamma and Beta radiation. For these reasons, it is the darling of many a home-made Geiger counter. According to some reports, the SI-22G and the equally impressive Soviet-made SBM-19 (aka STS-6) were developed for use in low flying airplanes to detect radiation “hotspots” after the big war ended (assuming anyone was still alive after the apocalypse).  Another report has these being used as “cosmic ray” detectors in large arrays of tubes strung together in parallel, pointed skyward with tons of lead shielding behind them to reduce earth-based radiation from obscuring the data from outer space.


    • Cathode Material: 446 Stainless Steel
    • Anode Material: Tungsten
    • Construction: Glass & Steel Envelope
    • Max. Length: 220mm (8.5”)
    • Maximum Diameter: 19mm (0.73”)
    • Recommended Anode Resistor:  10m
    • Starting Voltage: 285v
    • Recommended Operating Voltage: 400v
    • Operating Voltage Range: 360v-440v
    • Sensitivity: Gamma and Beta
    • Lifetime (est.):  1 x 10(9) (1 billion /20 years at normal background CPM)
    • Background CPM: 95 (in the Los Angeles/Southern California area)
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