The major problems affecting the low-power telemetry networks at Mount St. Helens have been weather and corrosive gases, with power supply problems secondary. Lightning and vandalism have also been concerns. We have found that these problems can be minimized with proper site preparation and instrument packaging. Airtight instrument cases protect sensitive electronic equipment from corrosive gases and moisture. Nonmetal instrument cases are used in highly corrosive environments where metal cases quickly deteriorate. Instrument cases are protected from direct exposure to the environment by enclosures ranging from metal drums to small buildings. Problems due to rime ice formation on the antennas are minimized by using antennas protected by radomes or by using log-periodic antennas. Circuit damage from lighting and from improper power connections during battery changes may be minimized by grounding and use of diodes and transient-suppressant devices. To power remote sites, we have used solar panels with rechargeable batteries, primary batteries, and propane-fueled thermoelectric generators. We find solar panels with rechargeable batteries to be the cheapest long-term power source although primary batteries are the most reliable power source. On-site repair and maintenance is made more difficult by poor conditions, requiring prior planning and realistic expectations. Attention to detail is the key to operating low-power telemetry networks.
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