In the early 1960's while working in the Crystal Design Laboratory at Hewlett-Packard, Don Hammond', the manager, and I began to look into a new mounting system for quartz crystals. Our goal was to design a package that could be cleaned by H2 firing at elevated temperatures, baked at temperatures greater than 3OO0C, sealed while in vacuum with leak rates that were less than any container available at that time and be impervious to Helium diffusion. Cost was of secondary concern.The first crystal unit that we were to design the system for was for our LC cut temperature sensor operating over the range -5OOC to +250°C. The unit was a 28 MHz 3d OT unit that was required to fit into a package no larger than a TO-5 configuration and maintain its Helium integrity for the life of the product.
Header dk can designWhile discussing the pros and cons of various materials and methods of construction, Mr.
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